ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Chemistry  (13,620)
  • EARTH RESOURCES AND REMOTE SENSING  (1,388)
  • Magnetism
  • 2010-2014
  • 1980-1984  (15,008)
  • 1925-1929
  • 1984  (7,322)
  • 1981  (7,686)
Collection
Keywords
Publisher
Years
  • 2010-2014
  • 1980-1984  (15,008)
  • 1925-1929
Year
  • 1
    Electronic Resource
    Electronic Resource
    Rǒle des electrons π des fonctions amide et ester dans les peptides et depsipeptides (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 169-185 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The IR data for the R1 CO-O-CHR2-CO-NHR3 derivatives are interpreted in terms of a H…π interaction involving the N—H bond and the π orbitals of the ester function and giving rise to a high ν(C=O) frequency and a low ν frequency. The resulting molecular conformation corresponds to the angular values φ # -90°, ψ # 0°. The H…π interaction in MeCO-L-Lac-NHMe is highly destabilized by water and aprotic solvents but is retained in methanol. Considering the high ν(C=O) ester or amide frequency of the middle function in β-folded depsipeptide or peptide sequences, it may be supposed that the residue indexed i + 2 in β turns experiences a H…π interaction which has a stabilizing effect on β turns. Some examples concerning valinomycin and some model compounds are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200112
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Masthead (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200201
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Polyelectrolyte contribution to the persistence length of DNA (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 251-268 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The difference between the theories of Manning, on the one hand, and of Odijk and Skolnick and Fixman, on the other, for the polyelectrolyte contribution to the persistence length of DNA is shown to arise entirely from a subtle geometrical error in the theory of Manning. The corrected theory of Manning predicts a negligible polyelectrolyte contribution in 1.0M NaCl and only 33 Å in 0.01M NaCl, thus giving a change in total persistence length by a factor of only 1.07 over that range, in agreement with Odijk. Pertinent data in the literature indicate that the persistence length must change by a factor of ≤ 1.6 between 1.0 and 0.01M NaCl, and very likely by less than a factor of 1.4. Evidently, the intrinsic rigidity of the uncharged double-strand filament dominates the bending rigidity at NaCl concentrations above 0.01M.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200202
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Conformational studies of peptides: Crystal and molecular structures of L-3,4-dehydroproline and its t-butoxycarbonyl and acetyl amide derivatives (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 283-302 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structures of L-3,4-dehydroproline, t-butoxycarbonyl-L-3,4-dehydroproline amide, and acetyl-L-3,4-dehydroproline amide have been determined. L-3,4-Dehydroproline is orthorhombic with a = 16.756, b = 5.870, c = 5.275 Å, and Z = 4; t-butoxycarbonyl-L-3,4-dehydroproline amide is orthorhombic with a = 6.448, b = 8.602, c = 21.710 Å, and Z = 4; acetyl-L-3,4-dehydroproline amide is monoclinic with a = 4.788, b = 10.880, c = 7.785 Å, β = 105.25°, and Z = 2. The final R value for the L-3,4-dehydroproline is 0.046 based on 529 reflections; for t-butoxycarbonyl-L-3,4-dehydroproline amide, 0.050 based on 792 reflections; and for acetyl-L-3,4-dehydroproline amide, 0.058 based on 632 reflections. The structures clearly establish that the free amino acid exists in the zwitterionic form in the crystalline state. The molecular conformations of the t-Boc and acetyl derivatives consist of two planes: one involving the primary amide and the other the remaining atoms of the molecule. The acetyl-L-3,4-dehydroproline amide contains a tertiary amide bond in the cis conformation. To the best of our knowledge, this is the first example of a cis bond in an acetyl derivative of an amino acid or peptide. At variance with the previously reported proline amides, which present φ and ψ values corresponding to those of a right-handed α-helical conformation (conformation A), the t-Boc and acetyl derivatives both have φ and ψ values corresponding to a collagenlike conformation (conformation F).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200204
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Physical properties of type i collagen in solution: Structure of α-Chains and β- and γ-components and two-component mixtures (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 359-371 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of thermally denatured Type I collagen has been studied using laser light scattering. The results indicate that the diffusion coefficients of α-chains and β- and γ-components are 1.550 ± 0.08 × 10-7, 1.000 ± 0.05 × 10-7, and 0.835 ± 0.04 × 10-7 cm2/sec, respectively, at temperatures between 20 and 40°C. It is concluded from diffusion data that these species have hydrodynamic radii of about 13.8 nm (α-chain), 21.5 nm (β-component), and 25.7 nm (γ-component), consistent with previous studies of thermal denaturation by light scattering. It is also concluded, based on volume calculations, that a large volume increase occurs when the triple helix unfolds. Homodyne correlation functions for two component mixtures of α-chains and β-and γ-components appeared to decay exponentially. In all but one case discussed the correlation function could be fitted with a single component having a translational diffusion coefficient which was an intensity weighted average of the diffusion coefficient of each component present.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Theoretical π-π* circular dichroic spectra of helical poly(glycine) and poly(L-alanine) as functions of backbone torsion angles (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 387-397 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichroic spectra and oscillator strengths of the π-π transition near 190 nm are calculated for helical (Gly)6 and (Ala)6 at 30° intervals of the backbone torsion angles (φ,ψ) over the range -180° ≤ φ ≤ -60°, -60° ≤ ψ ≤ 180°, using the partially dispersive normal mode treatment of the dipole interaction model. Polarizabilities of atoms and the NC′O group are those determined semiempirically in previous studies. Calculations for (Ala)6 at (φ,ψ) angles corresponding to the α-helix, the poly(Pro) II helix, a collagen single helix, a poly-(MeAla) helix, and single β-helices are found to agree well with most of the available experimental data.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200210
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Interaction of the antimalarial drug fluoroquine with DNA, tRNA, and poly(A): 19F-NMR chemical-shift and relaxation, optical absorption, and fluorescence studies (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 435-449 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of the fluorinated antimalarial drug fluoroquine [7-fluoro-4-(diethyl-amino-1-methylbutylamino)quinoline] with DNA, tRNA, and poly(A) has been investigated by optical absorption, fluorescence, and 19F-nmr chemical-shift and relaxation methods. Optical absorption and fluorescence experiments indicate that fluoroquine binds to nucleic acids in a similar manner to that of its well-known analog chloroquine. At low drug-to-base pair ratios, binding of both drugs appears to be random. Fluoroquine and chloroquine also elevate the melting temperature (Tm) of DNA to a comparable extent. Binding of fluoroquine to DNA, tRNA, or poly(A) results in a downfield shift of about 1.5 ppm for the 19F-nmr resonance. The chemical shift of free fluoroquine depends on the isotopic composition of the solvent (D2O vs H2O). The solvent isotope shift is virtually eliminated by fluoroquine binding to any one of the nucleic acids. 19F-nmr relaxation experiments were carried out to measure the spin-lattice relaxation time (T1), 19F{1H} nuclear Overhauser effect (NOE), off-resonance intensity ratio (R), off-resonance rotating-frame spin-lattice relaxation time (T1ρoff), and linewidth for fluoroquine in the nucleic acid complexes. By accounting for intramolecular proton-fluorine dipolar and chemical-shift anisotropy contributions to the fluorine relaxation, all of the relaxation parameters for the fluoroquine-DNA complex can be well described by a motional model incorporating long-range DNA bending on the order of a microsecond and an internal motion of the drug on the order of a nanosecond. Selective NOE experiments indicate that the fluorine in the drug is near the ribose protons in the RNA complexes, but not in the DNA complex. Details of the binding evidently differ for the two types of nucleic acids. This study provides the foundation for an investigation of fluoroquine in intact cells.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200303
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Hydrodynamic behavior and molecular conformation of poly(L-lysine HBr) in carbonate buffer solution (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 345-357 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In carbonate buffer at pH 10.5, a transparent solution of poly(L-lysine HBr) was obtained up to fairly high concentration of 3 g/dl at room temperature. The hydrodynamic behavior of the solution has been studied by sedimentation analyses and viscosity measurements. A dimer form for high concentrations and a monomer form for low concentrations were inferred. The dimer and monomer forms were assigned to a β-structure and α-helix, respectively, based on the CD and optical rotary dispersion spectra. Using CD spectroscopy, a reversible transition between α-helix and β-structure was observed as a function of either poly(L-lysine HBr) concentration or temperature. An aggregated form which was assigned to the antiparallel pleated sheet appeared at 50°C on the basis of its ir spectrum.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200207
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Stability and geometry of hydrogen-bonded complexes of peptides (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 707-718 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Observations of induced circular dichroism (CD) bands in chloroform solution demonstrate the formation of specific, asymmetric complexes of the aromatic ligands 2-pyridone and 2,6-dichlorobenzoic acid with cyclic dipeptides of the general formula cyclo(L-Pro-X). The induced CD changes sign with the configuration of X due to subtle influences of the side chain on the geometry of the complex. Computations of interaction energies suggest that a plausible model for the complex of an aromatic ligand with the -CONH- of the cis secondary amide is a nearly planar arrangement of six heavy atoms in a ring containing two hydrogen bonds. The observed CD is matched by that computed for a tilt of the aromatic ligand toward the side chain of X. Binding constants were determined from the induced CD as a function of ligand concentration. For dichlorobenzoic acid these are about 450m-1 for the secondary amide and 50m-1 for the tertiary amide. For pyridone the binding constant is about 45m-1 for either the secondary or tertiary amide. For comparison self-dimerization constants determined by vapor-pressure osmometry in chloroform solution at 25°C are 870, 350, 50, and 20m-1 for pyridone, benzoic acid, dichlorobenzoic acid, and cyclo(L-Pro-Gly), respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200407
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Proton and phosphorus nmr investigation of the conformational states of acid polyadenylic double helix (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 803-816 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Proton and phosphorus nmr have been used to investigate the double-helical structures of polyriboadenylic acid [poly(A)] formed in acidic solutions (pH 〈 6). The results obtained at low pH (∼4.5) are consistent with the model for the acid poly(A) double helix proposed by Rich [Rich, A., Davies, D. R., Crick, F. H. C. & Watson, J. D. (1961) J. Mol. Biol. 3, 71-86]. Other models that have been proposed are inconsistent with the nmr data. The nmr measurements have also been used to examine the conformation of poly(A) helix in the half-protonated state. Although the base-stacking arrangement of this state is similar to that observed in the more extensively protonated low-pH state, the phosphate backbone conformation is different from that found in either the neutral or low-pH structures.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200412
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Masthead (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Effect of some organic cosolvents on the reaction of hemoglobin with oxygen (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 39-51 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We studied the effects of some organic cosolvents (monohydric alcohols and amides) on the reaction of hemoglobin with oxygen. We present evidence showing that our data can be analyzed within the framework of the Monod-Wyman-Changeux model and that the main effect of cosolvents is to alter the T ⇄ R conformational equilibrium of hemoglobin, without significantly affecting the intrinsic oxygen dissociation constants. Following a previously described phenomenological approach, the overall effects have been separated into effects related to the variation of the bulk dielectric constant of the solvent and effects not related to the variation of this constant.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200104
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    XII. Conformational studies of histidine-containing peptides in solution (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 65-88 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spectroscopic properties (uv, CD, nmr) of histidine, glycylhistidine, histidylglycine, glycylhistidylglycine have been investigated in water and methanol in the temperature range 200-320 K in order to obtain information about their conformational equilibria. This analysis has been carried out for the different ionic forms of the compounds, in order to evaluate the influence of the ionization state of the carboxyl, histidyl, and amino groups on the rotamer distribution of the histidyl side chain (as evaluated from proton nmr analysis) and on the overall molecule (as judged from CD spectra). On the basis of certain approximations and from the temperature dependence of the proton nmr resonance, the thermodynamic parameters (ΔH° and ΔS°) characterizing the conformational equilibrium of the hystidyl side chain have been evaluated for the different structures and ionization states. Relatively large entropy differences between the rotamers are obtained in some cases. The data of the sidechain rotamer population, as determined by nmr, have been analytically correlated with the CD data, and in the case of hystidine and histidylglycine in basic solution, first-approximation values for the ellipticity of the single conformers have been evaluated. Finally, in the example of glycylhistidine and histidylglycine in basic solution, it is shown how the data obtained from the different experimental approaches (nmr and CD), as well as from theoretical energy calculations, converge to characterize the most stable conformation in solution.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200106
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Laser light-scattering analysis of the dimerization of transfer ribonucleic acids with complementary anticodons (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 155-168 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photon-correlation spectroscopy is a powerful technique for measuring the translational diffusion coefficient of particles and macromolecules in solution. In the study described here, this technique was used to analyze a specific dimerization process involving the association of two tRNA molecules through complementary anticodons. The tRNAs used in the analysis were E. coli tRNA2Glu and yeast tRNAPhe. The experimental data on the concentration dependence of the observed diffusion constants are shown to agree well with theoretical predictions. From these data, the equilibrium constant of the association reaction was determined for dimers formed over a wide range of temperatures and in several different solution conditions. In solutions of 0.1M ionic strength at 22°C, the equilibrium constants vary from 1 × 105M-1 in the absence of magnesium to 1.5 × 106M-1 in 10 mM Mg+2. The enthalpy and entropy changes for dimer formation in the absence and presence, 5 and 10 mM, of magnesium have been obtained from the temperature dependence of the equilibrium constant. The results show that both ΔH and ΔS contribute to the free energy of binding and that their relative contributions are similar for each solution condition evaluated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200111
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Dependence of DNA conformation on the concentration of salt (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 231-235 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200116
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Vibrational circular dichroism of poly(γ-benzyl-L-glutamate) (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 237-240 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200117
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Low-frequency modes in the raman spectrum of DNA (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 243-247 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200119
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Quantum-mechanical study of model molecules in relation to collagen structure. II. (Gly-Phe-Pro) and (Gly-Pro-Phe) repeating units (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 269-282 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A conformational quantum-mechanical study of (Gly-Phe-Pro) and (Gly-Pro-Phe) repeating tripeptide sequences has been carried out with the PCILO method. Using appropriate molecules as a model, we investigated the conformational possibilities of each in situ residue. Computations have been done taking into account the two typical pyrrolidine ring puckering and the most favorable orientations of the phenylalanyl side chain. Major conclusions drawn from this study are that the phenylalanyl can be accommodated at both second and third positions in the sequence without preventing the formation of triple-helix conformation. However, the analogy observed between the rotational possibilities around the second residue of Gly-Pro-Pro and Gly-Phe-Pro indicates that phenylalanyl in the second position favors the triple-helix formation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Neutron-scattering studies of the structure of chromatin core particles in solution (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 327-343 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of the nucleosome core particle in solution has been studied by neutron scattering using the full-contrast variation technique, which reduces the experimental spectra to three fundamental scatter functions holding information on shape and structure. Systematic calculations of the fundamental scatter functions expected from proposed core-particle models have been compared with the observed functions and show that the neutron-scattering criteria severely restrict the number of models which can be valid for the structure in solution. The best model for the core particle in solution has a hydrophobic histone core about which 1.7 ± 0.1 turns of DNA are wrapped at a pitch between 3.0 and 3.5 nm. This core contains most of the histone and has an average thickness of 4 nm and diameter 6.4-7.5 nm. While solution scattering is not able to specify uniquely the actual shape of the core to high resolution, all models which are possible for the shape of the core to a resolution justified by the data have been considered. It is clear that cylindrical or wedge shapes compatible with the above dimensions are valid structures. A hole probably penetrates the histone core, but the data do not allow a diameter greater than 1 nm. Available evidence suggests that about a quarter of the total histone is outside the core.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Relationship between proton-proton nmr coupling constants and substituent electronegativities. III. Conformational analysis of proline rings in solution using a generalized Karplus equation (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1211-1245 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between published vicinal proton-proton coupling constants and the pseudorotation properties of the pyrrolidine ring in L-proline, 4-hydroxy-L-proline, 4-fluoro-L-proline, and several linear and cyclic model proline peptides is investigated. Compared to earlier studies, several important improvements are incorporated: (1) a new empirical generalization of the classical Karplus equation is utilized, which allows a valid correction for the effects of electronegativity and orientation of substitutents on 3JHH; (2) an empirical correlation between proton-proton torsion angles and the pseudorotational parameters P and τm is derived; and (3) the best fit of the conformational parameters to the experimental coupling constants is obtained by means of a computerized iterative least-squares procedure. Two pseudorotation ranges were considered, classified as type N (χ2 positive sign) and type S (χ2 negative sign). The conformational equilibrium is fully described in terms of four geometrical parameters (PN, τN, PS, τS) and the equilibrium constant K. The present results indicate that, in general, the geometrical properties found in x-ray studies of proline and hydroxyproline residues are well preserved in solution. Several novel features are encountered, however. It is demonstrated that the proline ring occurs in a practically 1:1 conformational equilibrium between well-defined N- and S-type forms. Introduction of an amide group at the C-terminal end has no observable effect on this equilibrium, but the formation of a peptide bond at the imino nitrogen site results in a pronounced, but not exclusive, preference for an S-type form which is roughly 1.1 kcal/mol more stable than its N-type counterpart. The hydroxyproline ring system in neutral or acidic medium displays a pure N-type state, but N-acetylation results in the appearance of a minor (S-type) conformation. Cyclic proline dipeptides similarly exist in a biased conformational equilibrium. The major form (77-88%) corresponds to the N-type conformer observed in the solid state; the minor S-form has not been observed before. In contrast, cyclic hydroxyproline dipeptides display complete conformational purity. Ranges of endocyclic torsion angles deduced for the various classes of pyrrolidine derivatives in solution are presented. Each torsion appears confined to a surprisingly narrow range, comprising about 4°-8° in most cases. In all, the proline ring is far less “floppy” than hitherto assumed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200610
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Thermodynamics and equilibrium sedimentation analysis of the close approach of DNA molecules and a molecular ordering transition (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1305-1328 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurement of the equilibrium distribution of persistence length fragments of DNA in high concentration in the ultracentrifuge shows that the reduced osmotic pressure rises much faster than linearly. From analysis of the data in terms of the Zimm cluster integral we infer that the net interactions between helices are purely repulsive at all distances. A theoretical equation of state derived from scaled particle theory with one adjustable parameter is in excellent agreement with the experimental data so long as the salt concentration is not excessively low. The parameter represents the hard-core radius in a simplified approximation to the potential function for the electrostatic repulsion between helices. Its value depends on the salt concentration, and it shrinks at high salt to a radius in close agreement with direct structural estimates. At a particular value of the osmotic pressure that is only slightly salt dependent, the solution undergoes a reversible transition to a denser, turbid, optically anisotropic phase. The relation between DNA volume fraction, including the electrostatic radius, at the transition point and the effective asymmetry of the molecules as a function of salt is in approximate correspondence with various theoretical treatments. However, the experimental function extrapolates to the correct limit for spherical particles. The work needed to bring DNA to a high concentration is estimated. The results suggest that the phase transition is first order.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200615
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Quantitative test of Record's theory for proton-induced lowering of DNA melting temperature (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2121-2136 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This report presents a quantitative test of the ability of the counterion condensation theory to describe the proton-induced lowering of DNA melting temperature. From a general approach of Record et al. [Record, M. T., Anderson, C. F. & Lohman, T. H. (1978) Q. Rev. Biophys. 11, 103-178], we have obtained an expression that may be computer-fitted to the experimental data by numerical minimization of χ2. To do this, in addition to the assumptions made by Record et al., it was necessary to suppose that the interchange between protons and sodium is independent of pH and, due to the absence of data, take the enthalpies of protonation as thermally independent over the experimental temperature range. The dependences of the enthalpy of denaturation at neutral pH on sodium concentration and on G + C content were taken from literature. In the fitting process we have used 250 melting temperatures obtained at different pH and sodium concentrations for various natural DNAs. The theoretical expression gives a good quantitative description of the G + C and sodium concentration influences on the phenomenon but is only qualitative with respect to the dependence of dT/d log[Na+] on the pH. The adjusted pK values for the bases in denatured DNA agree with those for isolated deoxynucleosides. Interchange between sodium and protons is found to be less than 1:1. Calculated protonation enthalpies are ill-defined because of their low numerical influence. In short, it appears that the theory gives a good description of most of the aspects of the phenomenon even if it has some shortcomings, perhaps due to the great number of assumptions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201007
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Effects of some organic cosolvents on the functional properties of hemoglobin: Kinetics of O2 displacement by CO (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2137-2142 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We studied the kinetics of replacement of O2 by CO in hemoglobin in the presence and absence of organic cosolvents (methanol, ethanol, iso-propanol, n-propanol, formamide, acetamide, N-methyl-formamide) and at 10 and 25°C. Quantitative analysis of the results indicates that these cosolvents do not affect the intrinsic binding constants of ligands to the heme when hemoglobin is in the R conformation. The present results confirm the previously reported suggestion that the effects of the above cosolvents on the oxygen affinity of hemoglobin are related to effects on the T ⇄ R conformational equilibrium.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201008
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Influence of the telopeptides on type I collagen fibrillogenesis (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2195-2202 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparations have been made of acid-soluble collagens whose telopeptides have suffered different levels of proteolytic attack. The collagens with more intact telopeptides form fibrils more rapidly than those with degraded telopeptides. In addition, we have shown that a high molecular weight aggregate rich in the carboxyterminal CNBr peptide, α1CB6, can be found in cyanogen bromide digests of fibrils formed from intact collagen. A similar aggregate is found in CNBr digests of native tendons. The aggregate formed in fibrils assembled in vitro can be stabilized by reduction, and its generation is strongly dependent on the presence of intact telopeptides. The latter point is the most objective evidence that to reproduce the characteristics of native fibrils in vitro, the collagen telopeptides must be preserved from proteolysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201012
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Free-sliding ligands: An alternative model of DNA-protein interactions (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2225-2241 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present an alternative to the common lattice model for nonspecific DNA-protein interactions by using ligands that translate freely along the polynucleotide instead of binding to distinct lattice sites along the polynucleotide chain. The general model we present corresponds to a one-dimensional continuum gas and is referred to as the “continuum model” to distinguish it from the general lattice model. Explicit expressions are obtained for the binding isotherm equation for two version of the continuum model, including the effects of binding-site exclusion and attractions between bound ligands. Theoretical results are compared to those obtained from the McGhee-von Hippel (1974) analysis of the lattice model with cooperative interactions between ligands occupying more than one lattice site. Practical applications of the continuum model are illustrated by analyzing (i) the noncooperative binding to single-stranded DNA by RNase (Jensen and von Hippel, 1976), and (ii) the highly cooperative binding to poly(rA) by a proteolyzed fragment of the gene 32 protein of phage T4 (Lonberg et al., 1981).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201015
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Simulations of the solvent structure for macromolecules. II. Structure of water solvating Na+-B-DNA at 300 K and a model for conformational transitions induced by solvent variations (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2427-2483 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of water and its interaction energy with a fragment of B-DNA composed of 12 base pairs and of the corresponding 24 sugar and 22 phosphate units and Na+ ions (one at each phosphate group) are analyzed using Monte Carlo simulations. The sample of water molecules, at the simulated temperature of 300 K, is composed of 447 water molecules. The results are discussed either in terms of statistical analyses over the 2,000,000 simulated conformations (after equilibration) or with reference to an “average configuration.” Comparison is made to a simulation previously presented for the same system but without counterions. Isotherm at different relative humidity, hydration, and reactivity scales for different sites, the hydration number at each site, the structure of intraphosphate and interphosphate hydrogen-bonded filaments of water are reported and discussed. The stabilization of the B-conformation induced by the solvent with counterion (“ion-induced compression effect”) is analyzed on the base of the above findings. A preliminary model to predict conformational transition in DNA is presented. The analyses reported are very detailed to allow refined interpretations of spectroscopic (infrared, Raman, and nmr) and scattering (x-ray and neutron beam) data on DNA insolution.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201111
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Condensed states of nucleic acids. III. Ψ(+) and Ψ(-) Conformational transitions of DNA induced by ethanol and saltPaper II of this series is S.-M. Cheng and S. C. Mohr (1975) Biopolymers 14, 663-674. Portions of this work were presented at the XIth International Congress of Biochemistry, Toronto, Canada, July 1979. (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2533-2552 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational response of calf thymus DNA to solvent conditions altered by varying amounts of ethanol and NaCl has been monitored by circular dichroism (CD). These measurements, which extend over a much greater range of conditions than previously examined, reveal (above critical concentrations of ethanol and salt) a condensed form of the macro-molecule with unusually large positive ellipticity in the 250-300-nm region [the Ψ(+) state]. Mere increase in NaCl concentration at constant 35% (v/v) concentration of ethanol suffices to convert such Ψ(+) samples - via a series of intermediate forms with CD spectra resembling those of A-DNA, then B-DNA - into Ψ(-) states having anomalously large negative ellipticity similar to the well-known Ψ(-) forms produced by above-critical concentrations of poly-(ethylene oxide) and salt. These ethanol/salt-induced transitions are all completely reversible and can occur without formation of any visible precipitates. We suggest that they represent predominantly tertiary structural changes of B-form DNA molecules analogous to the changes which occur in several other systems where Ψ(+) ⇌ Ψ(-) interconversion has been reported. A “skein-of-yarn” model for the condensed tertiary (and quaternary, i.e., aggregated) state of the DNA affords one possible explanation for the inversions of ellipticity in all these cases. Such a model accords well with the accepted description of cholesteric liquid crystals.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201205
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Nmr studies of the rates of proline cis-trans isomerization in oligopeptides (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2623-2633 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-Nmr was used to measure the rate of cis-trans interconversion of X-Pro bonds in linear and cyclic oligopeptides. k(cis → trans) = 2.5 × 10-3 s-1 at 25°C was found for the zwitterionic form of H-Ala-Pro-OH, in good agreement with earlier measurements. Replacement of Ala by Phe, Tyr, or Trp resulted in a 10-fold slower interconversion rate, whereas after substitution of Ala by His or Glu, the rate decreased only slightly. Independent of the residues X, the interconversion rate was increased by a factor of ca. 20 when the peptide chain was elongated by addition of Ala to the C-terminal Pro. An additional increase by a factor of 6 was observed when going from the protected linear peptide CF3CO-Gly-Gly-Pro-Ala-OCH3 to the closely related cyclic compound c[-Gly-Gly-Pro-Gly-Ala-]. These data are evaluated with regard to their possible use in future studies on the role of X-Pro cis-trans isomerization in the kinetics of protein folding.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201209
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Contribution from the chirality of the growing chain to the enantiomer selectivity in activated-NCA polymerization of α-amino acid N-carboxyanhydride (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 507-524 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As a model compound for the growing chain in the activated-NCA type of polymerization of α-amino acid N-carboxyanhydride (NCA), 3-[ω-acetylglycyl-poly(α-amino acid) acyl]-α-amino acid NCA (called the prepolymer) having various degrees of polymerization (DPs) was synthesized by the polymerization of Phe, Val, Glu(OEt), and Asp(OBzl) NCA in the presence of AcGly NCA by the tertiary amine. Activated (S)-Phe, Val, Glu(OEt), and Asp(OBzl) NCA were added to the terminal cyclic group of the corresponding (S)- or (R)- prepolymer, and the enantiomer selectivity in the reaction was investigated. With prepolymers having DPs ranging from 1 to 15, the addition reaction always took place preferentially between species having the same configuration, and the degree of the enantiomer selection increased with increasing DP of the prepolymer. With prepolymers having DP = 1 and 2, we found contributions from the chiral terminal unit and the chiral penultimate unit to the enantiomer selection, respectively. Prepolymer having DP = 5 was shown to take a β-type conformation, which led to higher enantiomer selection; and prepolymers having DP = 10 and 15 were shown to take an α-helix conformation, which led to much higher enantiomer selection than did the β-type conformation. In the present investigation the mechanisms of terminal-unit control, penultimate-unit control and conformational control of the enantiomer selection in the activated-NCA type of polymerization were clearly observed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200307
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    Spectroscopic studies on the structure of poly(8-bromoadenylic acid): Effect of glycosidic torsion angle on the conformation and flexibility in polyribonucleotides (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 573-603 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The helix-coil transition and conformational structure of poly(8-bromoadenylic acid) [poly(8BrA)] have been investigated using 1H- and 13C-nmr, CD, and ir spectroscopy. The results have been compared with the structure of the related 5′-mono- and polynucleotides. The chemical shifts of H(2′), H(3′), C(2′), and C(3′) nmr signals show an interesting correlation with both the puckering of ribose ring and glycosidic bond torsion angle. Poly(8BrA) shows an upfield shift of the C(3′) signal and a downfield shift of the H(3′) signal compared to the chemical shifts in poly(A). These shifts are consistent with a C(3′) endo-syn conformation for poly(8BrA). A similar effect has been reported previously and is also observed here on the C(2′) and H(2′) signals when the preferred conformation is C(2′)endo-syn (e.g., in 5′-8BrAMP). The chemical-shift parameters thus act as a probe for studying syn ⇄ anti and N ⇄ S equilibria in solutions. The three-bond 1H-′13C coupling constants between H(1′) and C(8) and C(4) have been measured in poly(8BrA) and 5′-8BrAMP and their structural implications have been discussed. The observed preference of a C(3′)endo-syn conformation for poly(8BrA), coupled with other evidence, throws doubt on the validity of a correlation previously reported whereby a syn conformation is associated with a C(2′)endo ribose pucker. The backbone conformation of randomly coiled poly(8BrA) is very similar to the structures found in polyribonucleotides: poly(A) and poly(U). All three polymers show strong preferences for the backbone angles found in RNA helices. The CD spectrum of poly(8BrA) has a striking relationship to that of poly(A). The signs of all extrema are inverted, and the magnitudes are related by a constant factor. We suggest that these differences result from a change in the angle between coupled transition moment vectors in the two polymers. Infrared spectra of poly(8BrA) in H2O and D2O solution are reported for the frequency range below 1400 cm-1. The antisymmetric 〉PO2- stretching vibration is observed at an unusually low frequency in the helix (1214 cm-1). The symmetric 〉PO2- stretch occurs at ∼1095 cm-1 but is not resolved from a ring vibration near this frequency. A conformationally sensitive band, characteristic of helical RNA structures, is observed at 817 cm-1 and disappears when the helix is melted. This observation confirms the conclusion that ordered poly(8BrA) has a regular helical structure with an RNA backbone conformation. A stereochemical explanation is provided for the failure of poly(8BrA) (or other syn polymers) to form double helices with anti-polyribonucleotides.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200310
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    Kinetics of chemical modification of arginine and lysine residues in calf thymus histone H1 (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1103-1112 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The arginine and lysine residues of calf thymus histone H1 were modified with large molar excesses of 2,3-butanedione and O-methylisourea, respectively. Kinetic study of the modification reaction of the arginine residue revealed that the reaction is divided into the two pseudo-first-order processes. About a third (1 Arg) of the total arginine residues of the H1 molecule was rapidly modified without causing any detectable structural change of the molecule, and the slow modification of the remaining arginine residues (2 Arg) led to a loss of the folded structure of H1. In the case of lysine residue modification, 93% (56 Lys) of the total lysine residues of the H1 was modified with the same rate constant, while 7% (4 Lys) of lysine residue remained unmodified. When the reaction was performed in the presence of 6M guanidine-HCl, all of lysine residues were modified. It is concluded that the 2 arginine and 4 lysine residues resistant to modification are buried in interior regions of the H1 molecule and play an important role in the formation of the H1 globular structure, while the other 1 arginine and 56 lysine residues are exposed to solvent.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200602
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Optical anisotropies of amides and peptides in dioxane (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1191-1209 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molar Kerr constants mK, molar refractions mR, and dipole moments μ are reported for the N-methylacetamides CX3CONHCH3 (X = H, CH3, F. CI, Br) and acetamides CX3CONH2 (X = H, F, Cl, Br). The components of the polarizability tensor α are deduced for N-methylacetamide and acetamide on the basis of the bond additivity approximation. This α is found to be considerably more anisotropic than was indicated in previous determinations by other methods. The data for N-methylacetamide were used to calculate mK, μ, and γ2 (anisotropy squared) of N-acetyl-N′-methylglycine amide and N-acetyl-N′-methyl-alanine amide as functions of the torsional angles (φ,Ψ). The statistical mechanical averages of mK, μ, and γ2 were calculated from conformational energies obtained by the methods of Scheraga.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200609
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Elastin as a random-network elastomer: A mechanical and optical analysis of single elastin fibers (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1247-1260 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The physical properties of single, 5-8-μm diameter, water-swollen elastin fibers have been investigated on a microtest apparatus attached to a polarizing microscope. Analysis of the mechanical and optical properties at extensions below 100% indicate that the elastic modulus (G) has a value of 4.1 × 105 N m-2, the average molecular weight of chains between crosslinks is in the range of 6000-7100, and the stress optical coefficient (C′) is 1 × 10-9 m2 N-1 at 24°C. Analysis of the temperature dependence of the stress optical coefficient indicates that the polarizability of the random link decreases with increasing temperature, with an apparent activation energy for this process of the order of 1.6 kcal/mol. Analysis of the non-Gaussian mechanical and optical properties at extensions above about 100% suggest that the chains between crosslinks contain approximately 10 “effective” random links, with each link consisting of 7-8 amino acid residues. These parameters for the random chains in the elastin network have been used to predict the dimensions of other random proteins. The close correlation of these predictions with published values for the dimensions of a series of proteins in solution in 6M guanidinium hydrochloride provides an independent test of the appropriateness of our analysis.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200611
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Novel cell for light scattering from solutions (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1333-1335 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200617
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    n-Mer binding on a one-dimensional lattice of two-state m-site cells: Heavy meromyosin on regulated actin as an example (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1399-1411 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heavy meromyosin binding to F-actin saturated with tropomyosin is studied theoretically. The problem is formulated as a special case of n-mer adsorption to a one-dimensional Ising lattice which is divided into m-site-long blocks.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200704
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    Monte Carlo approach to the analysis of the rotational diffusion of wormlike chains (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1481-1502 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Monte Carlo analysis is presented which establishes a relationship between the rotational diffusion coefficients and the flexibility (persistence length, P) of short, wormlike chains. The results of this analysis are presented in terms of experimentally observable quantities; namely, the rotational relaxation times for the field-free decay of optical anisotropy. The pertinent theoretical quantity is R, defined as the ratio of the longest rotational relaxation time of a wormlike chain to the transverse rotational relaxation time of a rigid cylinder having the same axial length (L) and segmental volume. R, so defined, is essentially independent of the axial ratio of the cylinder for any value of L/P within the range of validity of the present analysis (axial ratio 〉 20; 0.1 〈 L/P 〈 5). It is pointed out that P can be determined with reasonable accuracy even in the absence of a precise knowledge of the local hydrodynamic radius of the chain.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200709
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    One hundred-fold acceleration of DNA renaturation rates in solution (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1537-1547 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvents which accelerate DNA renaturation rates have been investigated. Addition of NaCl or LiCl to DNA in 2.4M Et4NCl initially increases renaturation rates at 45°C and then leads to a loss of second-order behavior. The greatest accelerations are seen with LiCl and dilute DNA. Volume exclusion by dextran sulfate is the most effective method of accelerating DNA renaturation with concentrated DNA. Addition of dextran sulfate beyond 10-12% in 2.4M Et4NCl fails to increase the acceleration beyond approximately 10-fold. Accelerations of 100-fold may be achieved with 35-40% dextran sulfate in 1M NaCl at 70°C. No other mixed solvent system was found to be more effective, although acceleration may be achieved in solvents containing formamide or other denaturants. The acceleration in 2M NaCl occurs without loss of the normal concentration and temperature dependence of DNA renaturation and is also independent of dextran sulfate concentration if sufficient dextran sulfate is used. Dextran sulfate may be selectively precipitated by use of 1M CsCl.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200711
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Investigation of the flexibility of DNA using transient electric birefringence (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1503-1535 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the preceding article, a Monte Carlo analysis was presented which provides a quantitative numerical relationship between the rotational diffusion coefficients, as measured by the decay of optical anisotropy following an electric field pulse, and the flexibility (persistence length) of short, wormlike chains. In the present article, the results of the foregoing analysis are applied to the observed rates of decay of birefringence for a series of sequenced DNA fragments ranging in size from 104 to 910 base pairs. Under the conditions used in this study, the DNA fragments exist as native, duplex molecules. Furthermore, conditions are defined in which the observed relaxation times are not dependent on DNA concentration, field strength, or the duration of the pulse. It is pointed out that the ionic atmosphere associated with a wormlike polyion does not exert any significant (direct) influence on the rotational diffusion of the polyion and, therefore, that the rotational relaxation times are a true measure of the configurations of the DNA molecules in solution. Moreover, excluded-volume effects are shown not to be significant for the moderately short molecules employed in this study. The major conclusion of this study is that there is no strong ionic strength dependence of the persistence length for ionic strengths above 1 mM and that the persistence length, under conditions where electrostatic contributions are negligible, is approximately 500 Å. For ionic strengths significantly lower than 1 mM, electrostatic contributions to the stiffness of DNA become significant.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200710
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Structure of amphotericin B aggregates as revealed by UV and CD spectroscopies (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1575-1588 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aqueous and hydroalcoholic solutions of the heptenic macrolide amphotericin B display strong and variable signals in CD and absorption spectroscopies in the range of the π* ← π transition. An interpretation of the spectroscopic changes is proposed based on the equilibrium between two forms of the intermolecular organization: the aggregated one (A) with strong excitonic interaction and the nonaggregative one (B) whose spectra are like those of linear conjugated polyenes in true solution with a well-developed vibrational structure. The intermediate spectra are fitted by linear combination of the A- and B-form spectra. A two-level organization of the aggregates is proposed for the A-form: (1) a close packing of few molecules, which is the origin of the absorption maxima hypsochromic shift; and (2) interaction between the preceding small units inside the aggregates, which is spectroscopically expressed by the intense CD couplet.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200802
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Use of potentiometric titration for determination of α- and ω-peptide bonds in poly(aspartic acid) and poly(glutamic acid) (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1625-1633 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polypeptides of dicarboxylic amino acids having the monomer units linked in α- and ω-peptide bonds contain two kinds of carboxyls of different acidity. How well potentiometric titration can distinguish these two carboxyls and so characterize the nature of the peptide bonds is evaluated critically. An analysis of the equation describing the dependence of pH on the degree of neutralization based on neglecting the polymer effect and a discussion of the dissociation behavior of polyanions show that the method of evaluating experimental data found in the literature is incorrect. Nevertheless, if a conformational transition does not interfere, some useful and reliable information may be gained by this method; namely, an indication of the presence of two different peptide bonds, their mole ratio, and an approximate pK value for the carboxyl of the amino acid linked in the ω-peptide bond. The presence of two types of carboxyls complicates the evaluation of the titration curves in the conformation studies.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200806
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Conformational and structural constraints in double-helical polynucleotides (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1707-1725 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational analysis of antiparallel double-helical polynucleotides with Watson-Crick base pairing was reduced to a four-dimensional problem using original mathematical methods. In the four-dimensional conformational space the family of structures, characterized by the base-pair stacking with the most stable conformations in water solution as well as in the solid state, was localized. For the C′2-endo sugar pucker, both right-handed and left-handed structures were found; right-handed structures only, however, seem to be allowed for the C′3-endo pucker, the only possible one for ribonucleotides with base stacking.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200811
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Ethidium binding to deoxyribonucleic acid: Spectrophotometric analysis of analogs with amino, azido, and hydrogen substituents (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 83-110 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The DNA-ligand interactions of a series of phenanthridinium compounds with various combinations of amino, azido, and hydrogen functions at R3 and R8 were examined to determine the contribution of these particular substituents to ligand binding. Spectrophometric titrations using calf-thymus DNA emphasized the importance of amino substituents in conferring a strong interaction and also stabilizing the interaction against reversal by high ionic strength. Although azido groups were not as effective as amino groups, they were more effective than hydrogen functions in enhancing the interaction. Furthermore, an amino substitution at R8 was consistently, though only slightly, more effective than an amino substituent at R3. The results from superhelical titrations using plasmid pBR322 DNA demonstrated that analogs with amino and/or azido functions at both R3 and R8 produced the greatest unwinding, and compounds with an amino or an azido function at R8 proved more effective than those with the corresponding amino or azido substituent at R3.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230108
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Conformation and activity in angiotensin II peptides (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1971-1983 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Angiotensin II and its competitive inhibitor [Sar1, Ile8]-angiotensin II, as well as several analogs of these two compounds specifically chosen for their well-defined pharmacological properties, were studied by circular dichroism and nuclear magnetic resonance methods at various pH values in aqueous solution and in d6-dimethylsulfoxide. The results were compared with their biological activities. This allowed us to establish relationships between conformation and pressor activity, explaining most of the properties of angiotensin II, its inhibitor, and the analogs successively substituted in positions 3 and 5.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200919
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Tobacco mosaic virus as a carrier for small molecules: Artificial receptor antibodies and superhormones (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2011-2020 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Peptide agonists covalently attached to tobacco mosaic virus exhibit such unusual properties as superpotency, superaffinity, enhanced resistance towards enzymic degradation, and prolonged action at the target cell. These properties can be exploited for the isolation by density-gradient centrifugation of membrane vesicles bearing specific receptors for the peptides and for radioactive and fluorescent labeling of cell-surface receptors. Our observations can be explained by cooperative-affinity phenomena caused by the deployment in space of the agonist molecules.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200923
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Early stages of fibrinogen to fibrin conversion studied by static and dynamic light scattering (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2035-2049 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The early steps of fibrin aggregation induced by low Reptilase concentrations were studied by means of static and dynamic light scattering. In order to obtain information on the size and shape of the first oligomers, the angular dependence of the scattered intensity and the mean Rayleigh line width were measured. Under physiological pH and ionic strength, oligomer formation was detectable immediately after enzymatic activation. Comparison of the calculated data for different models with experimental results shows that the early fibrin polymerization proceeds as an end-to-end aggregation of elongated and possibly flexible molecules approximately 75 nm long.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201002
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    The equivalent conductivity of aqueous salt-free solutions of DNA: Influence of univalent counterions (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2083-2091 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equivalent conductivity of salt-free solutions of deoxyribonucleates of alkali metals and ammonium obtained by filtering an isoionic DNA solution through a cation exchanger in the corresponding form has been investigated in the concentrations range of 1 × 10-4 to 4 × 10-3M. For all counterions investigated there is a linear dependence of the equivalent conductivity on \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt {C_p} $\end{document}, where Cp is the nucleic phosphorus concentration. The limiting equivalent conductivity of deoxyribonucleates increases linearly with the limiting mobility of a counterion. By extrapolation to the zero mobility of the counterion, we have obtained the limiting mobility of a macroion, which is equal to 19 × 10-4 Sm m2 equiv.-1, which is in good agreement with the literature data for denatured DNA obtained by the method of a moving boundary. It is shown that the degree of binding of counterions calculated from the conductometric data in diluted DTA solutions in independent of the nature of the univalent counterion. The degree of dissociation of H+-DNA in the isoionic solution calculated with allowance for the fraction of unprotonated bases practically coincides with this value for salts of DNA. The parameter of Manning's theory calculated from the experimental data corresponds to the distance between phosphates along the chain of the macroion, which is equal to 6.7 Å. We attribute the smaller value of this distance as compared with the theoretical one for denatured DNA to the aggregation of macroions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201005
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Structure of cellulose II hydrate (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2165-2179 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A hydrate of cellulose II can be formed by swelling Fortisan fibers in hydrazine and then washing in water. The hydrate is stable at 93% relative humidity and has a monoclinic unit cell with dimensions a = 9.02 Å, b = 9.63 Å, c = 10.34 Å, and γ = 116.0°; the space group is P21. The unit cell contains disaccharide sections of two chains and approximately four water molecules. The structure was refined using the LALS method, based on 10 observed and 10 unobserved reflections. An antiparallel arrangement of adjacent chains was assumed, since this occurs in cellulose II (the starting material), and the hydrate also reverts to cellulose II on dehydration. Refinement of the positions and side-chain conformations of the chains shows that the chains are stacked in the same way as in cellulose II, and the hydrate is formed by insertion of water molecules between the stacks. However, all efforts to arrange the water molecules in crystallographically regular positions led to unsatisfactory agreement between the observed and calculated intensities. These results suggest an irregular arrangement of the water molecules, which was modeled using water-weighted atomic scattering factors. The analysis resulted in two refined models with relative chain staggers of ∼ +c/4 and ∼ -c/4, which are indistinguishable in terms of the x-ray agreement. Our preference is for the +c/4 model, for which the stacks of chains are analogous to those in cellulose II.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201010
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Interaction of calcium ions with α-elastin: An equilibrium dialysis, circular dichroism, and microcalorimetric study (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2213-2223 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of calcium ions with α-elastin has been investigated by equilibrium dialysis, CD, and microcalorimetric techniques. Consistent with literature data, it was found that the interaction in water is very poor. In trifluoroethanol (TFE), equilibrium dialysis experiments showed that calcium ions bind to ∼-elastin with an association constant of ∼250 L × mol-1. Such a figure is not consistent with highly specific, highly selective binding. It was also found that the CD response is not directly proportional to the amount of bound calcium but depends on the protein concentration. From microcalorimetric experiments it was found that the heat effect relative to the binding process is of the order of 1.9 kcal/g ion. From this figure and from the binding constant, a positive ΔS value of about 17 e.u. was evaluated, leading to the conclusion that the binding process is entropy driven. From microcalorimetric measurements a ΔH of 1.5 kcal/residue was found for the calcium-induced conformational transition of the protein.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201014
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Contributions of the PO ester and CO torsion angles of the phosphate group to 31P-nuclear magnetic shielding constant in nucleic acids: Theoretical and experimental study of model compounds (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 377-388 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The magnetic shielding constant of the 31P nucleus of the dimethylphosphate anion is calculated by an ab initio method for different values of the torsion angles about the PO ester bond and different orientations of the methyl groups. The results obtained tend to show that both types of conformational parameters contribute to the value of σ31P. The largest shielding is obtained when the methyl groups are staggered with respect to the PO bond; the smallest, for the eclipsed arrangement. Measurements carried out on the 16 deoxyribodinucleoside monophosphates show that in the majority of cases σ31P is shifted toward lower field for the dimers having large values of 3JPH3′ and 3JPH5′(5″). The theoretical results are discussed in relation to experimental data for polynucleotides and nucleic acids.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230215
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Low-frequency Raman scattering by anharmonic DNA modes with A⇌B character modeled with a classical double-well oscillator (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 471-491 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical modes of DNA that displace one strand against the other are modeled by the motion of an oscillator in an asymmetric quartic double-well potential whose minima represent the A- and B-conformations. Assuming that the variation of the polarizability during vibration derives mainly from the tilting of the base rings relative to the helix axis, the total polarizability tensor is shown to possess approximately ellipsoidal symmetry and to depend nonlinearly on the instantaneous displacement of the two strands. The Raman spectrum of a collection of randomly oriented molecules is calculated. It consists of one or more peaks with characteristic shape. The depolarization ratio is 3/4, independent of molecular conformation and frequency. The results are discussed in the light of existing experimental and theoretical information.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230306
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Conformational study of trinucleoside tetraphosphate d(pCpGpCp): Transition of right-handed form to left-handed form (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 511-536 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the semiempirical potential functions, conformational energies of the model compounds DMP-, d(pCp), d(pGp), and d(pCpGpCp) are calculated, and the B → Z transition is discussed along the pseudorotational path of the sugar ring. For dimethylmonophosphate anion, DMP-, the energy contour map is presented and the stabilities of the phosphodiester conformations discussed. For the sugar ring without the base attached, the minimum energies for each sugar-puckering form are calculated along the pseudorotational path. The energy barrier of the interconversion between the C(3′)-endo form and the C(2′)-endo form is calculated to be about 2.0 kcal/mol. From the conformational energy calculations of the interconversions of mononucleoside diphosphates, d(pCp) and d(pGp), between the C(2′)-endo conformer and the C(3′)-endo conformer, the purine sugar segment is known to be more convertible than the pyrimidine sugar segment. The results also support the finding that the pseudorotational transition occurred with the O(1′)-endo form more easily than with the O(1′)-exo form. Based on the results of conformational studies of DMP-, d(pCp), and d(pGp), a topological transition of the handedness of the model compound, d(pCpGpCp), is studied. The left-handed Z-form is found to be less stable by about 8.5 kcal/mol than is the right-handed B-form. The energy barrier of the Z → B transition is calculated to be about 17.4 kcal/mol. The contributions of the electrostatic and nonbonded energies to the energy barrier are discussed in connection with the conformation changes of the model compound, d(pCpGpCp).
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230308
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Microwave dielectric absorption of DNA in aqueous solution (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 593-599 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dielectric properties of aqueous solutions of DNA were measured at frequencies ranging from 0.1 to 12 GHz. The results are analyzed using the Maxwell mixture theory and yield a value for the hydration of the DNA of about 0.4 g/g, which is in the range observed in other investigations. No evidence was found for an additional absorption effect at microwave frequencies, which has been predicted to occur in certain DNA analogs due to the vibrational excitation of the double helix by the applied microwave field.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230312
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    Self-association of the neuroregulatory peptide substance P and its C-terminal sequences (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 747-758 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Self-association of substance P and its C-terminal partial peptide sequences was studied by CD, quasi-electric light scattering, and sedimentation experiments. CD spectra of these peptides are strongly influenced by self-association. They exhibit strong characteristic negative ellipticities, suggesting the formation of a presumably B-type ordered structure. The tendency to form multimers depends on chain length and constitution and has its maximum at the octapeptide (SP 8). The peptide multimers have a broad distribution of sizes in the range of 30- and 800-nm diameter. Subdivision of this distribution into two size classes gives mean diameters of 60-100 nm (predominating)/200-800 nm for substance P and 30-50 nm/200-800 nm for SP 8 multimers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230413
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    13C-NMR chemical shifts and the conformations of rigid polypeptides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 819-829 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-nmr chemical shifts of backbone carbonyl and side-chain β-carbons in polypeptides provide structural information. Recent utilization of substituent effects on 13C-nmr chemical shifts (principally γ-effects) has permitted the rationalization of their sequence and conformation dependence when observed in linear, flexible polypeptides. In this report, we apply the γ-effect method to study the 13C-nmr chemical shifts observed in solution and in the solid state for the backbone carbonyl and side-chain β-carbons in conformationally rigid polypeptides, which are usually cyclic. As found previously for flexible, linear polypetides, the relative 13C-nmr chemical shifts observed for the backbone carbonyl and side-chain β-carbons in conformationally rigid polypeptides are predictable from knowledge of their peptide residue sequence (primary structure) and conformation (secondary structure) via the γ-effect method.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230419
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Eu(III) ion binding to poly(L-glutamate) anion studied by environment-sensitive laser spectroscopy (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 847-852 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230502
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Circular dichroism studies of α-aminoisobutyric acid-containing peptides: Chain length and solvent effects in alternating Aib-L-Ala and Aib-L-Val sequences (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 877-886 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CD spectra of the peptides Boc-X-(Aib-X)n-OMe (n = 1, 2, 3) and Boc-(Aib-X)5-OMe, where X = L-Ala or L-Val have been examined in several solvents. The X = Ala and Val peptides behave similarly in all solvents, suggesting that the Aib residues dominate the folding preferences of these peptides. The decapeptides adopt helical conformations in methanol and trifluoroethanol, with characteristic negative CD bands at 222 and 205 nm. In the heptapeptides, similar spectra with reduced intensities are observed. Comparison with nmr studies suggest that estimates of helical content in oligopeptides by CD methods may lead to erroneous conclusions. The pentapeptides yield solvent-dependent spectra indicative of conformational perturbations. Peptide association in dioxane results in an unusual spectrum with a single negative band at 210 nm for the decapeptides. Disaggregation is induced by the addition of methanol or water to dioxane solutions. Aggregation of the heptapeptides is less pronounced in dioxane, suggesting that a critical helix length may be necessary to promote association stabilized by helix dipole-dipole interactions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230505
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    Interaction of poly-5-bromouridylic acid. II. Thermodynamic analysis of its interaction with adenosine and 9-methyladenine (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 831-841 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of poly-5-bromouridylic acid [poly(BU)] with adenosine and 9-methyladenine was studied by equilibrium dialysis, optical melting, and microcalorimetry. The stacking free energy, ω, was estimated as -17.6 kJ/mol for adenosine·2poly(BU) and -18.8 kJ/mol for 9-methyladenine·2poly(BU) from the binding isotherms constructed from equilibrium dialysis results. The binding isotherms constructed from a series of melting curves also gave ω values for adenosine·2poly(BU). The thermal stability of the complex depends on monomer concentration, and the partial molar enthalpies of the complex formation at the midpoint of the transition were evaluated from the Tm coefficients as a function of free monomer concentration. The values of -92.0 and -90.4 kJ/mol were obtained for adenosine·2poly(BU) and 9-methyladenine·2poly(BU) in 0.4M NaCl-0.02M Na-cacodylate-5 × 10-4M EDTA (pH 7.0), respectively. Microcalorimetric measurements provided lower integral heats of reaction values for these complexes, i.e., -73.2 kJ/mol for adenosine·2poly(BU) and -71.5 kJ/mol for 9-methyladenine·2poly(BU). A comparison with a polyribouridylic acid system provided a quantitative understanding of a stabilization by bromination in terms of thermodynamic parameters.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230420
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230201
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Comment on breathing and bending in DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 191-194 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230202
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Structure of hydrated Na+ ions around a region of A- or B-DNA helix (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 257-270 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A molecular-dynamics simulation was used to carry out an introductory study of the hydration of a section of a rigid single A- or B-DNA helix with one Na+ counterion per nucleotide. Four Na+ ions and four nucleotides and periodic boundary conditions were used to mimic an infinite helix. The atoms of the helix and the Na+ ions were assumed to be Lennard-Jones spheres that also carried charges. Stillinger four-point charge model water molecules were used. We carried out five calculations, for 26 and 46 water molecules in B-DNA and 20, 32, and 46 in A-DNA fragments. The arrangements of the Na+ ions are found to have some similarities to those obtained by Clementi and Corongiu. In the calculations with 46 water molecules, we found that two Na+ ions can be bridged by about two water molecules and form a hydrated bound pair, which in turn forms a bridge between the guanine N7 and a near phosphate group. These bound pairs may be important in stabilizing the helix structure of DNA molecules.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230207
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    The C-terminal extrahelical peptide of type I collagen and its role in fibrillogenesis in vitro: Effects of Ethylurea (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 313-323 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ethylurea was used to weaken hydrophobic interactions during collagen fibrillogenesis in vitro. Intact and enzyme-digested type I collagen was studied. In all preparations, ethylurea decreased the extent and rate of fibril formation, inhibition being greatest in the enzyme-digested collagens. With intact collagen (and probably also with carboxypeptidasedigested collagen), there was no evidence the ethylurea altered the mechanism of fibril growth; in pepsin-digested collagen, however, the growth mechanism was altered by ethylurea, possibly reflecting a conformational change of the “hydrophobic cluster” in the C-terminal peptide. Such a structural change could occur in a hydrophobic environment once the distal portion of the C-terminal peptide (presumed to be essential for its structural stability) is removed by pepsin. The results further emphasize the importance of hydrophobic interactions in collagen fibril nucleation and growth in vitro.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230210
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230601
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    X-Ray crystallographic analysis of a ternary intercalation complex between proflavine and the dinucleoside monophosphates CpA and UpG (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1025-1041 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report the crystal-structure analysis of a complex involving the drug proflavine and the two dinucleoside monophosphates cytidylyl-3′,5′-adenosine (CpA) and uridylyl-3′,5′-guanosine (UpG). The planar drug molecule is intercalated between C⃛G and U⃛A Watson-Crick base pairs, in a double-helical fragmentlike arrangement. Sugar conformations at the 3′-ends of the two strands are dissimilar. The backbone conformations fall within the ranges of values noted previously for dinucleoside intercalation complexes, and some correlations involving these are noted. The separation of the two strands and the basic twist angle of 16°, compared to other reported complexes, are indicative of sequence-dependent effects of the drug binding.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230605
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Mean-square helical hydrophobic moments in partially ordered proteins (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1057-1066 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Helical hydrophobic moment ratios, 〈h2〉/〈H2〉, have been evaluated for 34 polypeptides under conditions where the helix content is dictated solely by the short-range interactions operative in aqueous media. The mean-square helical hydrophobic moment is denoted by 〈h2〉, and 〈H2〉 is the averaged of the squared hydrophobicites. This ratio would be one in absence of any correlation in the hydrophobicities of amino acid residues in helices. The 〈h2〉/〈H2〉 tend to be substantially larger than values of the analogous ratio formulated for the mean-square dipole moments of typical synthetic polymers. For 24 of the 34 polypeptide chains considered, 〈h2〉/〈H2〉 is found to be greater than one, indicating a tendency to form helices with amphiphilic character. The ratio is exceptionally large in the case of the δ-hemolysins. It is also large for two other surface-active peptides, for two of the four apolipoproteins examined, and for myohemerythrin. A much smaller 〈h2〉/〈H2〉 is found for melittins. If melittins is to form helices with large 〈h2〉/〈H2〉, the configurational statistics must be governed by effects in addition to those short-range interactions that occur when water is the solvent.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230607
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230701
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    β-Bend conformation of CH3CO-Pro-Pro-Gly-Pro-NHCH3: Implications for posttranslational proline hydroxylation in collagen (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1193-1206 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational-energy computations have been carried out for the N-acetyl-N′-methylamides of the Pro-Pro, Pro-Gly, and Gly-Pro dipeptides and of the Pro-Pro-Gly-Pro tetrapeptide, serving as models for the conformational analysis of single-stranded poly(Gly-Pro-Pro). The probability of β-bend formation for the Pro-Gly sequence is very high, viz., 0.72 for the terminally blocked Pro-Gly dipeptide, and rises to 0.86 in the tetrapeptide. The β-bend conformations of the Pro-Gly sequence are of low energy in single-chain poly(Gly-Pro-Pro) as well. The β-bend structure had been postulated earlier to be a requirement for post-translational proline hydroxylation during the biosynthesis of collagen. The present results lend strong support to this proposal by demonstrating that the β-bend structure is energetically favorable and hence can be accommodated easily in single-stranded poly(Gly-Pro-Pro).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230705
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Circular dichroic studies on Cu(II) interactions with a protamine, scylliorhinine Z3 (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1241-1248 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of Cu(II) with the protamine scylliorhinine Z3 was studied by means of CD measurements. At a 1:1 molar ratio, three complexes are formed. (1) In the pH range 5-6.5, the results suggest the formation of a five-membered chelate ring through the coordination of two nitrogen atoms, the N-terminal and the contiguous peptide nitrogen. (2) At pH ≥ 6.4, there is involvement of the lateral NH2 group of Arg; at pH 6.5-8, the formation of a 3N cupric complex is strongly suggested. (3) At pH ≥ 8, results indicate the formation of a 4N complex as a major species in Cu(II)-Z3 solution. The transformation from a 2N to a 3N complex, and from a 3N to a 4N complex was followed with the help of the σ(αNH2) → Cu(II) charge-transfer dichroic band transitions. At Cu(II):Z3 molar ratios ≥ 2 and at pH 〉 8, a new dichroic band appears, indicating the involvement of the tyrosine residue side chain in metal-ion complexation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230708
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Liquid crystallinity in collagen solutions and magnetic orientation of collagen fibrilsPresented at the Macromolecular Symposium of the International Union of Pure and Applied Chemistry, July 12-16, 1982, Amherst, Massachusetts. (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1261-1267 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of the optical birefringence of solutions of acid-soluble collagen from rat-tail tendon at 22°C in the pH range 1.0-6.0 show that collagen exhibits an isotropic to mesophase transition only between pH 2.4 and 3.0 at 10% weight concentration. Such liquid crystalline order is probably essential for the orientation of collagen in a magnetic field. When solutions of neutral salt-soluble collagen were precipitated at pH 7.0 by warming to 37°C (“heat gelling”) in a magnetic field of ca. 20 kG, the resulting fibrils wee oriented perpendicular to the direction of the field. Heat gelling is shown to be a useful technique for maintaining the orientation induced in precursor solutions even after the sample is removed from the magnetic field.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230710
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Ionic and structural effects on the thermal helix-coil transition of DNA complexed with natural and synthetic polyamines (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1295-1306 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyamines are ubiquitous cellular components that interacts strongly with nucleic acids. Although many of the interactions of oligocations with DNA can be rationalized with polyelectrolyte theories that treat counterions as point charges, some structural effects are evident. We have explored the effects of polyamine structure on one important aspect of DNA behavior, its thermal melting transition, by using a series of spermidine analogs NH3(CH2)3NH2(CH2)nNH33+, where n varies from 2 to 8 [Jorstad et al. (1980) J. Bacteriol. 141, 456-463]. For spermidine itself, n = 4. Tm for calf-thymus DNA in the presence of each of these analogs, and the other naturally occurring polyamines putrescine2+ and spermine4+, was measured over a wide range of NaCl concentrations and polyamine:DNA phosphate ratios. There are modest, but significant structural effects. particularly with the shorter n = 2 and 3 derivatives, whose geometry my not allow full electrostatic interaction with DNA. Longer analogs, on the other hand, are not much different than spermidine in their effects on Tm, though a moderate maximum occurs at n = 5. Since polyamines are important in the cellular condensation and packaging of DNA, we have also delineated the critical polyamine and salt concentrations that are required to cause DNA aggregation. Here again, there are significant structural effects, which are not easily rationalized by any simple considerations.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230713
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Circular dichroism of core DNA in mononucleosomes: A theoretical model (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1315-1323 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The observed difference between the CD spectrum of B-DNA mononucleosomes and that of free DNA has been attributed to the tertiary structure of the core DNA. This conjecture is tested here. The tertiary structure is modeled as an optical system consisting of two identical, planar, linear retarders rotated with respect to each other. The retarders have the same linear birefringence and linear dichroism as oriented B-DNA. Such an optical system is circularly dichroic. The predicted wavelength dependence and magnitude of the CD are in reasonably close agreement with the experimental results.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230715
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Induced optical activity in the complex of poly(L-arginine) with azo dyes (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1367-1377 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absorption and CD spectra of the complexes of poly(L-arginine) (PLA) and azo dyes have been measured in aqueous solution. On complexation, Blue-shifted additional absorption bands were observed. In the wide pH 4-11 range, induced CD was observed at the visible wavelengths corresponding to the blue-shifted absorption bands. The induced CD arose from the dimeric dye molecules bound to PLA in the α-helical structure. When a modified analysis of induced CE is made by the excition chirality method, the origin of the induced CD can be assigned to the dipole coupling. The PLA-dye complexes showed the counterlockwise (negative, S) chirality of the transition dipole moments of dyes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230719
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    pH-jump titration of the tyrosyl groups of bovine plasma albumin (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1347-1365 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ionization properties of the tyrosyl groups of bovine plasma albumin in various conformational states - the native state (N), the two acid states (F and E), and the state (B) stable at slightly alkaline pH - were studied by means of a stopped-flow-pH-jump technique. The technique allows us to obtain the tyrosyl titration curve in a conformational state that is unstable in the pH region of the titration. The pH jumps from the N and B states to various alkaline pH's, where the tyrosines ionize to bring about a time-dependent increase in absorption at 296 nm, indicating that a number of the tyrosines buried initially become susceptible to ionization as a result of the alkaline transition occurring above pH 10.8. Extrapolation of the observed absorption change to zero time gives a spectrophotometric titration curve in the initial conformational state. Only 30-401% of the 19 tyrosines of the protein can ionize both in the N and the B state at pH 12. The pH jumps from the F and E states, on the other hand, give a decrease in absorption between pH 9 and 11.7, indicating that the tyrosyl groups initially exposed are remarked by refolding after the pH jumps, and the zero-time titration curves show that essentially all the tyrosyl groups ionize normally in these acid states. The results are discussed in relation to the known results of the tyrosyl exposure of the protein measured by other techniques, and the consistency among them demonstrates the effectiveness of the pH-jump titration method. Hydrogen bonding between the abnormal tyrosyl and carboxylate groups as a mechanism to stabilize native albumin is suggested from characteristics of the alkaline transition, which also involves the exposure of the tyrosyl groups, and from the tyrosyl titration curves in the native and acid states.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230718
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Fluctuational base-pair opening in DNA at temperatures below the helix-coil transition region (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1137-1139 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230614
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Synthesis of oligopeptides consisting of L-leucyl-L-leucyl-L-ananyl and L-methionyl-L-methionyl-L-leucyl repeating units with an improved preparation of Nps-amino acids (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1397-1409 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two series of peptides with hydrophobic side chains, Nps-(L-Leu-L-Leu-L-Ala)n-OEt and Nps-(L-Met-L-Met-LLeu)n-OEt (n = 1-6), were synthesized by the fragment condensation method using dicyclohexylcarbodiimide in the presence of N-hydroxysuccinimide. The tripeptide fragments were prepared stepwise by dicyclohexylcarbodiimide-mediated reaction of Nps-amino acids, which were synthesized by an improved rapid procedure.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230721
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Dielectric properties of aqueous solutions of sonicated DNA above 40 MHz (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1457-1463 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dielectric properties of sonicated calf-thymus DNA sodium salt in aqueous solutions have been studied in the frequency range from 40 MHz to 2 GHz by time domain spectroscopy (TDS). A dielectric dispersion not previously reported was found, which has a characteristic frequency of about 150 MHz. All of the dielectric parameters are insensitive to the size of DNA fragments and to helix-to-coil transitions. The study of this dispersion as a function of DNA concentration and temperature allows us to conclude that it may be due to counterion fluctuation on short sections, probably in a direction transverse to the macromolecular axis.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230803
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Polypeptide matrices as active catalytic supports for stereoselective electron-transfer reactions (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1465-1479 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of L-adrenaline (epinephrine) in the presence of [Fe(tetpy)(OH)2]+ ions bound to poly(L-glutamate) or to poly(D-glutamate) has been studied at pH 7 (tetpy = 2,2′:6′,2″:6″,2‴-tetrapyridyl). Electron transfer from the substrate to the central metal ion, which is rate-determining, proceeds stereoselectively only when extensive and possibly specific interactions between adrenaline and the peptidic residues of the ordered polymer in the close environment of the active sites occur. This ensures different steric constraints for the two diastereomeric precursor complexes, which are thought to affect the separation and orientation of the redox centers differently, leading to the observed phenomena. Some data on the catalytic oxidation of L-dopa(3,4-dihydroxyphenylalanine) are also presented, showing stereoselective effects similar to those observed with L-adrenaline, despite the diverse distance of the chiral center from the reacting OH groups. A mechanistic interpretation of the results is discussed in the light of a few general considerations concerning the structural features of the catalytic systems. Possible explanations for the finding that stereoselectivity occurs at the expense of the efficiency of catalysis are also considered.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230804
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Determination of peptide conformation via vibrational coupling: Application to diastereoisomeric alanyl dipeptides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1917-1930 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solution-phase Raman spectra of diastereomeric alanyl dipeptides, D-Ala-L-Ala and L-Ala-L-Ala, and various mono- and dideuterated isotopomers in H2O and D2O, are reported. Spectral differences between the diastereomeric forms are interpreted, using the Raman analog of the coupled oscillator model, in terms of geometric differences between certain vibrations in the diastereomeric forms. Application of the coupled-oscillator formalism allows the determination of a dihedral angle between the coupling vibrations. The results are compared with vibrational coupling employed by other workers in the determination of the vibrational spectra of peptides.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231008
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Theoretical studies on the conformation of saccharides. VIII. Solvent effect on the stability of β-cellobiose conformers (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1951-1960 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational equilibria of five β-cellobiose conformers have been studied theoretically in 10 solvents. The stability of the conformers in dilute solution has been compared by using the method that has already been tested for 2-methoxytetrahydropyran, β-maltose, and D-glucose. The solvation energy consists of electrostatic, dispersion, and cavity terms which have been determined from the properties of the solute calculated by the PCILO quantum-chemical method and physicochemical properties of the solvents. The calculated abundance of conformers depends on the solvent (e.g., in dioxane C1:C2:C3:C4:C5 = 60.0:34.1:2.9:2.0:1.0; in dimethylsulfoxide, 75.5:22.1:1.8:0.5:0.2; and in water, 82.2:16.2:1.3:0.2:0.1). The results obtained indicate that the preponderant conformer in the aqueous solution is similar to the one adopted by β-cellobiose in the crystalline form. The role of individual contributions to the solvation energy have been analyzed. Based on the determined abundance of conformers, averaged residual optical activity and nmr parameters have been calculated and compared with observable properties. The marked differences observed between solvent-induced conformational changes for β-cellobiose and β-maltose have been discussed from the viewpoint of the solubility of the cellulose.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231011
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Theoretical studies on protein-nucleic acid interactions. II. Hydrogen bonding of amino acid side chains with bases and base pairs of nucleic acids (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1995-2008 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With a view to understanding the role of hydrogen bonds in the recognition of nucleic acids by proteins, hydrogen bonding between the bases and base pairs of nucleic acids and the amino acids (Asn, Gln, Asp and Glu, and charged residues Arg+, Glu-, and Asp-) has been studied by a second-order perturbation theory. Binding energies have been calculated for all possible configurations involving a pair of hydrogen bonds between the base (or base pair) and the amino acid residue. Our results show that the hydrogen bonding in these cases has a large contribution from electrostatic interaction. In general, the charged amino acids, compared to the uncharged ones, form more stable complexes with bases or base pairs. The hydrogen-bond energies are an order of magnitude smaller than the Coulombic interaction energies between basic amino acids (Lys+, Arg+, and His+) and the phosphate groups of nucleic acids. The stabilities of the complexes of amino acids Asn, Gln, Asp, and Glu with bases are in the order: G-X 〉 C-X 〉 A-X U-X or T-X, and G · C-X 〉 A · T(U)-X, where X is one of these amino acid residues. It has been shown that Glu- and Asp- can recognize guanine in single-stranded nucleic acids; Arg+ can recognize G · C base pairs from A · T base pairs in double-stranded structures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231014
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    Conformation of control and acetylated HeLa stripped chromatin after reassociation with H1 (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2195-2210 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of histone H1 on the conformation and stability of control and acetylated HeLa high-molecular-weight chromatin that had been stripped of H1 and nonhistone proteins was compared by circular dichroism (CD) and thermal denaturation measurements. Two different preparations of H1, originating from rat thymus and chicken erythrocyte, were used in the reconstitution studies. The control and acetylated stripped chromatin had identical CD and thermal denaturation properties, as did their reconstitutes with rat thymus H1. Reconstitutes of the two chromatins with chicken erythrocyte H1 had similar CD properties, but thermal denaturation studies showed that the acetylated reconstitute was destabilized compared to the control reconstitute. Reconstitutes of both chromatins with chicken erythrocyte H1 had a more condensed and stabilized structure than the reconstitutes with rat thymus H1. Thus, acetylation caused a decrease in the stability of chromatin in the presence of erythrocyte H1, but more marked differences were detected in the structure of stripped chromatin after reassociation with different H1 preparations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231107
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Kinetics of formation of fibrin oligomers. III. Ligation kinetics concurrent with and subsequent to oligomer assembly (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 127-138 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Human fibrinogen was treated with thrombin in the presence of fibrinoligase (Factor XIIIa) and calcium ion at pH 8.5, ionic strength 0.45, and the ensuing polymerization was interrupted at various time intervals (t) both before and after the clotting time (tc) by solubilization with a solution of sodium dodecyl sulfate and urea. Aliquots of the solubilized protein were subjected to gel electrophoresis on polyacrylamide gels after disulfide reduction by dithiothreitol and on agarose gels without reduction. The degree of γ-γ ligation was determined from the former. The latter provided the size distribution of ligated end-to-end sequences produced by splitting the ligated staggered overlapped oligomers down the middle, for degrees of polymerization, x, from 1 to 10. Addition of fibrinoligase (in which the activating thrombin had been inhibited by p-nitrophenyl-p′-guanidinobenzoate, NPGB) to Kabi fibrinogen showed the presence of small amounts of ligatable oligomers. Addition of fibrinoligase to a polymerizing mixture in which the action of thrombin had been stopped before clotting by NPGB produced the same distribution of ligated end-to-end sequences that was obtained when fibrinoligase was originally present, at least for reaction times up to 0.7 of the clotting time. The kinetics of γ-γ ligation by fibrinoligase acting on a polymerized mixture stabilized by NPGB were followed. The reaction was first order in the concentration of ligatable γ-γ junctions and the initial velocity was proportional to the enzyme concentration. The time evolution of size distribution of ligated end-to-end sequences agreed with a theory based on random ligation of ligatable junctions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230110
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Mean-square hydrophobic moment for partially helical polypeptides (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 201-212 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mean-square helical hydrophobic moment, 〈h2〉, is defined for polypeptides in analogy to the mean-square dipole moment, 〈μ2〉, for polymer chains. For a freely jointed polymer chain, 〈μ2〉 is given by Σmi2, where mi denotes the dipole moment associated with bond i. In the absence of any correlations in the hydrophobic moments of individual amino acid residues in the helix, 〈h2〉 is specified by ΣHi2, where Hi denotes the hydrophobicity of residue i. The tendency for correlations in orientations of residue hydrophobic moments in helices therefore dictates the size of 〈h2〉/〈H2〉, where 〈H2〉 denotes the average value of ΣHi2 for all helices. The value of 〈h2〉/〈H2〉 will be greater than one in amphiphilic helices. A necessary prerequisite for this diagnostic usage of 〈h2〉/〈H2〉 is that the residue hydrophobic moment be oriented prependicular to the principal axis of the helix. Matrix-generation schemes are formulated that permit rapid evaluation of 〈h2〉 and 〈H2〉. The behavior of 〈h2〉/〈H2〉 is illustrated by calculations performed for model sequential copolypeptides.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230204
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Monte Carlo determination of the distribution of ions about a cylindrical polyelectrolyte (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 271-285 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report a calculation of the distribution of small ions around a charged cylinder representing a polyelectrolyte molecule in solution. The Monte Carlo method of Metropolis, Rosenbluth, and Teller was used to avoid the inaccuracies known to be associated with the Poisson-Boltzmann equation. The systems examined contained a long polyelectrolyte cylinder with charge parameter, χ, equal to 4.2, corresponding approximately to a DNA molecule. In one model, the cylinder had charges on its axis and an exclusion radius to the center of the small ions equal to 10 Å, while the small ions had various radii in the range from 1 to 10 Å and one or two protonic charges. Various systems were studied; some had one species of small ion alone, others had mixtures of different types. The results showed good agreement with the solution of the Poisson-Boltzmann equation when only the species with 1-Å radius was present, but considerable discrepancies appeared with larger ions as a result of excluded volume interactions between the latter. Deviations from the Poisson-Boltzmann equation also appeared when both positive and negative small ions were present; the deviations were in the direction of a higher concentration of both counter- and co-ions, but particularly co-ions, close to the polyelectrolyte. In another model, the charges were arranged along two helices on the surface of the cylinder; the resulting radial distribution of small ions was not much different from that found when the charges were situated on the axis. In all cases there was a striking accumulation of counterions in a layer of concentration exceeding 1 mol/L at the surface of the polyion.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Variation of longitudinal acoustic velocity at gigahertz frequencies with water content in rat-tail tendon fibers (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 337-351 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Brillouin scattering was used to determine the longitudinal acoustic velocity along the axis of collagen fibers as the relative humidity decreased from 95 to 0%. Between 0 and 86%, the velocity decreased linearly at a modest rate. Above 86%, the decrease was steep. The changing mass of the absorbed water accounts for most of the velocity change in the lower humidity range. The remaining deviation is probably due to variation of the elastic coupling between molecules. At low humidity, the adsorbed water is known to be attached to the collagen molecules, whereas the additionally adsorbed water at high humidity has the properties of bulk liquid. The high-humidity sonic velocity variation is ascribed to the presence of free water. It is possible to identify the five water regimes of Pineri et al. [(1978) Biopolymers 17, 2799-2815] with the variations of the sonic velocity with water content.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230212
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Studies of collagen fold formation in aqueous solutions of α-gelatin III (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 353-361 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Optical rotation, viscosity, and density studies are reported on solutions of α-gelatin in solvent mixtures of water and various monohydric alcohols. Reversion to the collagen fold by the protein is shown to be order in all cases, but changes in magnitude as a function of concentration of the particular alcohol are observed. The structuring effects of the alcohol on water are seen to be reflected in the extent of helix regeneration by the protein. Shorter chain alcohols appear to influence the initial rate of reversion by direct interaction with the protein.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230213
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230301
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    A high-resolution 13C-nmr study of collagenlike polypeptides and collagen fibrils in solid state studied by the cross-polarization-magic angle-spinning method. Manifestation of conformation-dependent 13C chemical shifts and application to conformational characterization (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2279-2297 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have recorded high-resolution 13C-nmr spectra of collagen fibrils in the solid state by the cross-polarization-magic-angle-spinning(CP-MAS)method and analyzed the spectra with reference to those of collagenlike polypeptides. We used two kinds of model polypeptides to obtain reference 13C chemical shifts of major amino acid residues of collagen (Gly, Pro, Ala, and Hyp): the 31-helical polypeptides [(Gly)nII, (Pro)nII, (Hyp)n, and (Ala—Gly—Gly)nII], and the triple-helical polypeptides [(Pro—Gly—Pro)n and (Pro—Ala—Gly)n]. Examination of the 13C chemical shifts of these polypeptides, together with our previous data, showed that the 13C chemical shifts of individual amino acid residues are the same, within experimental error (±0.5 ppm), among different polypeptides with different primary sequences, if the conformations are the same. We found that the 13C chemical shifts of Ala residues of the 31-helical (Ala—Gly—Gly)n and triple-helical (Pro—Ala—Gly)n are significantly displaced, compared with those of the α-helix, β-sheet, and silk I form, and can be utilized as excellent probes to examine conformational features of collagen-like polypeptides. Further, the 13C chemical shifts of Gly and Pro residues in the triple-helical polypeptides are substantially displaced from those found in (Gly)nII and (Pro)nII of the 31-helix, reflecting further conformational change from the 31-helix to the supercoiled triple helix. In particular, the 13C chemical shifts of Gly C = O carbons of the triple-helical polypeptides are substantially displaced upfield (4.1-5.1 ppm), with respect to those of the 31-helical polypeptides. These displacements are interpreted by that Gly C = O of the former is not involved in NH … O = C hydrogen bonds, while this carbon of the latter is linked by these kinds of hydrogen bonds.On the basis of these 13C chemical shifts, as reference data for the collagenlike structure, we were able to assign the 13C-nmr peaks of Gly, Ala, Pro, and Hyp residues of collagen fibrils, which are in good agreement with the values expected from the model polypeptides mentioned above. We also discuss a plausible conformational change of collagen fibrils during denaturation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231111
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Proton magnetic resonance studies on dermorphin and its peptide fragments (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2349-2360 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dermorphin (Tyr—D-Ala—Phe—Gly—Tyr—Pro—Ser—NH2), a potent natural peptide opioid, its synthetic L-Ala2 analog, and all the N fragments from the tripeptide (Tyr—D-Ala—Phe—NH2) to the parent hexapeptide amide were characterized for the first time by means of proton nmr spectroscopy at 11.74 T. Assignments of most protons of dermorphin were facilitated by the study of the N-terminal fragments. Comparison of spectroscopic parameters with relative pharmacological activity is proposed as a possible means of studying flexible agonists in solution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231116
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Magnetic circular dichroism of adenine, hypoxanthine, and guanosine 5′-diphosphate to 180 nm (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2715-2724 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The magnetic circular dichroism (MCD) of adenine, hypoxanthine, and guanosine 5′-diphosphate reveals that, for each species, the uv-absorption band near 200 nm is composed of at least two electronic transitions. The theory of MCD shows that the dipoles of these transitions are not parallel to one another. The transitions are assigned within the framework of current theories of the electronic structure of the purines. Knowledge of the presence of more than one transition within an absorption envelope is important in interpreting the corresponding natural CD of DNA and RNA.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Evidence for an interwound form for the superhelix in circular DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2963-2966 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231219
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Aggregation of poly(γ-benzyl-α,L-glutamate) (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 719-734 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aggregation of poly(γ-benzyl-α,L-glutamate) and its enantiomer in toluene has been investigated by following the viscosity as a function of temperature, concentration, molecular weight, molecular-weight distribution, helix chirality, and shear rate. The temperature and concentration data for a 138,000-molecular-weight sample was fitted to an open, reversible end-to-end aggregation model. The aggregation numbers resulting from this fit were consistent with the sudden onset in non-Newtonian flow resulting from only a 0.2-wt% increase in concentration. The association equilibrium constant was then used to predict viscosity for comparison with other data, in particular, the effect of molecular weight and molecular-weight distribution. A mixture of right-and left-handed helices showed the aggregation was not chiral selective. The stiffness of end-to-end aggregated (hydrogen-bonded) molecules differed little from their covalent counterparts, at least below a molecular weight of ∼106. We conclude that polybenzylglutamate aggregation in toluene can be described by an open end-to-end aggregation model.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230411
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Quasielastic light-scattering studies on dinucleosomal-sized DNA: Ionic-strength dependence (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 797-808 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quasielastic light-scattering (QELS) studies were performed on a monodisperse preparation of dinucleosomal-sized DNA having an average of 375 base pairs. The QELS data were obtained at several time intervals at each angle examined over the range 30° 〈 θ 〈 60° for the ionic strength solvents 500, 50, 10, and 1 mM in KCl. What results from this study is that two relaxation domains persist over the entire ionic strength range where the “splitting” between these two domains increases as the ionic strength is lowered. The ordinate intercept of Dapp vs Cp/2Cs, where Cp is the polyion concentration and Cs is the added salt concentration, is shown to give the “true” hydrodynamic value for the diffusion coefficient. The “splitting phenomenon” is interpreted in terms of two models currently in vogue: small ion-polyion coupled modes and translational-rotational coupled modes for rigid rods in congested solutions. Although neither model is in perfect agreement with the experimental results, the small ion-polyion coupled mode theory appears to provide a better quantitative description of the observations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230417
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230501
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    mini-chiuz (1981)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 15 (1981), S. A4 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19810150109
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Homogene Katalyse in der Technik (1981)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 15 (1981), S. 37-45 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19810150203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Platonische Kohlenwasserstoffe (1981)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 15 (1981), S. 52-61 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19810150205
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Elektroanalytische Methoden IITeil I: Diese Zeitschr. 15, 21 (1981).: Cyclische Voltammetrie (1981)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 15 (1981), S. 62-67 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19810150206
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Front cover (1981)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 15 (1981), S. coi 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19810150301
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Masthead (1981)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 15 (1981) 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19810150302
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...