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
  • 1
    Electronic Resource
    Electronic Resource
    Secondary structure of peptides. 18. 15N-nmr and 13C-nmr CP/MAS investigation of the primary and secondary structure of (Ala/Val) copolypeptides (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 2113-2129 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various copolypeptides were prepared by benzylamine or tertiary amine-initiated copolymerizations of alanine-N-carboxyanhydride (Ala-NCA) and valine-N-carboxyanhydride (Val-NCA). The number-average molecular weights of these copolypeptides were detemined by 1H-nmr spectroscopic end-group analyses and viscosity measurements. The sequences were characterized by 15N-nmr spectra in solution, and the average lengths of the homogeneous blocks were determined from the signal intensities. The 50.3-and 75.4-MHz 13C-nmr CP/MAS spectra of the solid copolypeptides are not sensitive to sequence effects, but allow qualitative and quantitative analyses of the secondary structures. In contrast to other methods, the 13C-nmr spectra allow determination of the extent to which individual amino acids are incorporated into β-sheet or α-helix phases. Depending on primary structure and molecular weight, the secondary structure of (Ala/Val) copolypeptides may vary significantly. Both monomer units may be predominantly helical or predominantly β-sheet structure, or the Val units may prefer the β-sheet structure with most Ala-units forming β-helices. However, these secondary structures are more or less thermodynamically unstable and revert to the stable conformations on reprecipitation from trifluoroacetic acid/water.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360241108
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Use of natural-abundance 15N-nmr spectroscopy to investigate the secondary structure of peptides: Gramicidin S (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 1815-1826 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The natural-abundance 15N-nuclear magnetic resonance (nmr) spectrum of the cyclic decapeptide gramicidin S has been measured and assigned in the solvents dimethyl sulfoxide, methanol, and 2,2,2-trifluoroethanol. Three methods have been investigated to distinguish between peptide groups which are exposed to or shielded from the solvent. The solvent dependence of the 15N chemical shift is correlated with the two types of peptide group in gramicidin S—those with the carbonyl group exposed or shielded from the solvent. The second method monitors the lability of the N—H proton (via the collapse of the reduced 15N-1H coupling) in the presence of added base used to promote intermolecular exchange - peptide protons shielded from the solvent exchange more slowly. The third method looks at the temperature dependence of the 15N chemical shifts in dimethyl sulfoxide. Here the data are not so distinctive as to allow the differentiation between solvent-exposed or shielded N—H bonds at all peptide groups.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360191010
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Voafrine A and Voafrine B, New Dimeric Indole Alkaloids from Cell Suspension Cultures of Voacanga africana Stapf (1983)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 66 (1983), S. 2525-2533 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of voafrine A and voafrine B, two novel dimeric indole alkaloids isolated from Voacanga africana Stapf cell suspension cultures, were established and the medium-dependent formation of both alkaloids was investigated.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19830660818
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and Characterization of (5′-Deoxyadenosin-5′-yl)cobalamin ( = ‘Adenosylcobalamin’) Analogues Mimicking the Transition-State Geometry of Coenzyme-B12-Dependent Rearrangements (1993)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 76 (1993), S. 2367-2383 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A convergent synthesis of the five novel analogues 1a-e of (5′-deoxyadenosin-5′-yl)cobalamin ( = ‘adenosylcobalamin’) is described. The analogues 1a-e carry oligomethylene chains (C3-C7) inserted between the central Co-atom and the 5′-O-atom of the adenosine moiety and are thought to mimick the transition-state geometry in coenzyme-B12-catalyzed rearrangement. All five analogues were characterized by NMR, UV, and FAB mass spectrometry.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19930760623
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Peptidkonformationen, 27. cyclo-[L-Pro-(Bzl)Gly-D-Pro]. Synthese und Konformation im Kristall und in Lösung (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3164-3181 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Peptide Conformations, 27, cyclo-[L-Pro-(Bzl)Gly-D-Pro]. Synthesis and Conformation in the Crystal and in Solution270, 300, and 500 MHz 1H and 67.89 MHz 13C NMR spectra of cyclo[L-Pro-(Bzl)Gly-D-Pro] (1) (Bzl = N-Benzyl) were analyzed with the aid of two-dimensional techniques. A 300 MHz spin echo correlated 1H NMR spectrum (SECSY) yielded the information about coupling pattern. Small long range couplings, which are important for signal assignments, were detected by a special modification of the Jeener spectroscopy. This spectrum is compared with the conventional Jeener spectrum. Carbon- and proton-connectivities result from a 2D-1H-13C shift correlation. Coupling constants and chemical sift values in the proline rings were obtained by iterative simulation of both seven-spin systems. The interpretation of the NMR parameters yields a rapid equilibrium between two boat conformations; one of them is strongly preferred (80%). This conformation was also fond in the X-ray crystal structure.
    Notes: 270-, 300- und 500-MHz-1H- sowie 67.89-MHz-13C-NMR-Spektren von cyclo[L-Pro-(Bzl)Gly-D-Pro] (1) (Bzl = N-Benzyl) wurden mit Hilfe ein- und zweidimensionaler Techniken analysiert. Ein 300-MHz-spin-echo-korreliertes 1H-NMR-Spektrum (SECSY) lieferte die Kopplungsinformation. Für Zuordnungen wichtige sehr kleine Weitbereichskopplungen wurden durch eine spezielle Modifikation der Jeener-Spektroskopie erkannt. Dieses Spektrum wird mit dem konventionellen Jeener-Spektrum verglichen. Die Verknüpfung von Kohlenstoff- und Wasserstoff-Atomen ergab sich aus einem 2D-verschiebungskorrelierten 1H-13C-NMR-Spektrum. Die Kopplungskonstanten und chemischen Verschiebungen der Protonen wurden durch Simulation der beiden 7-Spin-Systeme der Prolinringe erhalten. Die Interpretation der NMR-Daten ergibt ein schnelles Gleichgewicht zweier Bootkonformationen, von denen jedoch eine deutlich überwiegt (80%). Diese Konformation wurde durch Röntgenstrukturanalyse auch im Kristall nachgewiesen.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160915
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    15N NMR spectroscopy 14Part 13: Cf.12. Neighboring residue effects in glycine-containing polypeptides (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 161-174 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The sequence polypeptides (Ala*-Ala-Gly)n, (Ala-Gly*-Gly)n, (Leu-Gly-Gly)n, (Val-Gly-Gly)n, and (Pro-Gly-Gly)n were synthesized by known methods, and their natural abundance 15N NMR spectra were measured in trifluoroacetic acid. These spectra were compared with those of other previously described sequence polypeptides and with the corresponding homopolypeptides. The spectra of all sequence polypeptides exhibit neighboring residue effects, so that glycine nitrogen atoms acylated by other χ-(or ω-)amino acids have chemical shifts different from that of the Gly-Gly bond. These neighboring residue effects cannot be summarized or explained by simple rules; however, they are useful for the characterization of copolypeptides. Such an application was tested in the case of four sequence polypeptides consisting of isomeric sequences of identical monomeric units. All isomeric sequences can be distinguished from each other, and the observed shift effects could be related to the neighboring residue effects of other copolypeptides.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800115
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    15N NMR spectroscopy, 2.Part 1: cf.8. Detection of tacticity in polypeptides (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 253-259 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780126
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    15N NMR spectroscopy, 17.Part 16: H. R. Kricheldorf, Makromol. Chem. 180, 1707 (1979). Stereospecificity of the polymerization of D,L-alanine-NCA and D,L-valine-NCANCA: N-carboxyanhydride. (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 1715-1727 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: D,L-Alanine-NCA containing 1,5% 15N and D,L-Valine-NCA containing 2,4% 15N, were synthesized and polymerized under various conditions. 36,48 MHz 15N NMR spectra of the resulting poly(D,L-amino acid)s were measured in trifluoroacetic acid, and the peak for the isotactic triad in each polymer was assigned by comparison with other alanine- and valine containing polypeptides. In the case of D,L-alanine-NCA the formation of isotactic blocks was favored, when the “activated monomer mechanism” was operating. In the case of D,L-valine-NCA, however, syndiotactic blocks were predominantly formed under the same reaction conditions. The initiation with primary amines results in almost atactic sequences. A helical secondary structure of the growing peptide chain is found to be an unnecessary condition for the stereospecificity of a NCA polymerization. The synthesis of Boc-D,L-Ala-D,L-Ala-OMe from tert-butoxycarbonyl-D,L-alanine and D,L-alanine methyl ester was carried out under various conditions, and the stereospecifity was investigated by means of natural abundance 15N NMR spectra. The results are discussed with respect to the polymerization of D,L-alanine-NCA and D,L-valine-NCA.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800709
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    15N NMR spectroscopy, 22Part 21, cf.: H. R. Kricheldorf, W. E. Hull, Macromolecules in press.. Influence of shift reagents and paramagnetic ions on the spectra of peptides and polyamides (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 507-515 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The influence of Eu(dpm)3 and Dy(fod)3 on the 15N NMR spectra of Z-Gly-Leu-Leu-OMe or Z-Ala-Leu-Leu-OMe was investigated; however, solvent effects were found to be more useful than shift reagents to improve the spectroscopic structure analysis of peptides. Furthermore, the influence of manganese and copper ions on the Nuclear Overhauser Effect and on the line width of benzyloxycarbonylglycine, polysarcosine, polyglycine and poly(β-alanine) was investigated in various solvents. The nature of the solvent was found to have a strong influence on the relaxation efficiency of the paramagnetic ions. Manganese ions can be used to shorten the pulse interval without risk of line broadening, when the measurements are carried out under the conditions of “inverse-gated-decoupling”.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1980.021810217
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    15N NMR spectroscopy, 25.Part 24: H. R. Kricheldorf, Org. Magn. Reson., in press. Terpolymerization of glycine-NCA, leucine-NCA, and valine-NCA (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 1949-1966 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The copolymerization of Leu-NCA and Val-NAC was achieved in solution by initiation with benzylamine, diethylamine, triethylamine, pyridine or by simple heating of the pure monomers to 120°C. Under similar conditions the terpolymerization of Gly-NCA, Leu-NCA and Val-NCA was carried out. 400 MHz 1H NMR spectra and natural abundance 36,48 MHz 15N NMR spectra of the resulting copolypeptides were measured in trifluoroacetic acid. The various kinds of peptide groups of these copolypeptides show individual 15N NMR signals because of strong neighboring residue effects. The quantitative evaluation of NMR spectra allows one to calculate the average length of the homogeneous blocks and the copolymerization parameters. The terpolymerization of Gly-NCA, Leu-NCA and Val-NCA was found to behave like a superposition of the corresponding binary copolymerizations. The primary amine-initiated terpolymerization of Gly-NCA, Val-NCA and γ-methyl Glu-NCA, was also investigated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1980.021810915
    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...