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  • 1
    Electronic Resource
    Electronic Resource
    The in vivo formation and repair of DNA adducts from 1′-hydroxysafrole (1981)
    New York, NY : Wiley-Blackwell
    Journal of Supramolecular Structure and Cellular Biochemistry 16 (1981), S. 83-90 
    Details
    ISSN: 0275-3723
    Keywords: safrole ; 1′-hydroxysafrole ; 1′-acetoxysafrole ; carcinogen-DNA adducts ; DNA repair ; 5-bromodeoxyuridine density labelling ; repair patch size ; Chemistry ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: 1′-Hydroxysafrole is a proximate carcinogenic metabolite of the naturally occurring hepatocarcinogen safrole. Comparison by high-performance liquid chromatography of the nucleoside adducts obtained from hepatic DNA of adult female mice treated with [2′,3′-3H]1′-hydroxysafrolc with those formed by reaction of deoxyribonucleo-sides with electrophilic derivatives of 1′-hydroxysafrole indicated that the four in vivo adducts studied were derived from an ester of 1′-hydroxysafrole. Three of the four adducts comigrated with products of the reaction of 1′-acetoxysafrole with deoxyguanosine, whereas the fourth adduct comigrated with the major reaction product of the ester with deoxyadenosine. Analysis of the three deoxyguanosine ad-ducts indicated that all three involve substitution on the 2-amino group of guanine. A sample of the major adduct prepared from deoxyguanylic acid has been charac-terized from its NMR spectrum as N2-(trans-isosafrol-3′-Y1)-deoxyguanosine, and the deoxyadenosine adduct has been similarly characterized as N6-(trans-isosafrol-3′-yl)-deoxyadenosine.Repair replication was measured in cultured human T98G cells exposed to 1′-acetoxysafrole using the combined 5-bromodcoxyuridine density label and radioiso-topic label metnod. At a concentration of 1 mM 1′-acetoxysafrole, the amount of repair synthesis approached maximum values only about 15% of those obtained af-ter saturating doses of ultraviolet light. Repair patch size distribution was found to be similar in cells treated with ultraviolet light or 1′-acetoxysafrole as determined by the density of repair-labeled DNA relative to that of parental DNA.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jsscb.1981.380160108
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  • 2
    Electronic Resource
    Electronic Resource
    Interactions of molecules with nucleic acids. III. Steric and electrostatic energy contours for the principal intercalation sites, prerequisites for binding, and the exclusion of essential metabolites from intercalation (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 2067-2089 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on steric and electrostatic considerations, the prerequisites for binding to DNA via the intercalation mechanism are proposed. Steric contour energy curves are presented to demonstrate the region inaccessible to an intercalant. They are calculated with a 6-n (n = 14) potential. This method is a soft potential analog of an excluded-volume approach. Electrostatic contours on the steric surface illustrate the relatively positive and negative regions of the binding site. The principal intercalation sites, predicted to fit into B-DNA via a tetramer-duplex unit, and the unconstrained dimer-duplex units, obtained in crystal structures, are examined. These contours illustrate the requirements of size, conformation, and net atomic charges necessary for intercalation and optimum binding. Based on the limited space available for intercalation by the presence of the backbone and the maximum base-pair separation of 8.25 Å, an Essential Metabolite Exclusion Hypothesis is presented.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360191110
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  • 3
    Electronic Resource
    Electronic Resource
    Interactions of molecules with nucleic acids. VI. Computer design of chromophoric intercalating agents (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 633-652 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mode of action of many antitumor agents entails the inhibition of nucleic acid synthesis. Because many of the drugs can intercalate, it is assumed that intercalation is an important step in the mechanism of biological activity. As intercalants contain a planar chromophore as an ingredient essential for intercalation, chromophores that should fit into DNA are desired. This is the main theme of this investigation. Binding to DNA of fundamental moieties, protonated pyridine, aniline, phenol, quinone, and 4H-thiopyran-4-one, is studied to determine their optimum placement in DNA. The optimum orientations for each moiety are superimposed to form polyaromatic systems that can intercalate in a manner in which functional groups on these chromophores are oriented as in the moieties themselves. Ideal intercalants proposed contain three and four fused ring system, have protonated ring nitrogen atoms located to maximize the electrostatic interactions with DNA, hydroxy and amino groups that can hydrogen bond to the OII and O5′ phosphate backbone atoms, and carbonyl and sulfur groups in the central position of the ring system to provide variations in the chromophore and to interact with the relatively positive region in the intercalation site. The optimum orientation occurs when the chromophore and the base pairs overlap to the maximum extent. The ideal intercalants are fundamentally of the type:
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210311
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  • 4
    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
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  • 5
    Electronic Resource
    Electronic Resource
    Interactions of molecules with nucleic acids. VII. Intercalation and T·A specificity of daunomycin in DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 139-158 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intercalation complexes of daunomicin(+1) with tetramer duplexes in DNA are studied with the theoretically determined intercalation sites (I, -0.4), (II, -0.4), and (III, -1.4). These sites occur with base pairs separated by 6.76 Å for helical angles of 26°, 22°, and 8° about the intercalation site. Site I is preferred, and this is in agreement with experimental unwinding angles. Optimum binding positions and conformations are established, and these are in agreement with experimental results from crystal structures. A systematic procedure is devised to study base-pair and base-sequence specificity, which results in the demonstration that the most stable sequences are mainly ↑BP1, T·A, DAUN, A·T, BP4↓ and ↑BP1, T·A, DAUN, G·C, BP4↓, i.e., with the TpA and CpG (pyrimidine)p(purine) sequences about the intercalation site. These 32 possible sequences are found among the 40 most stable complexes. These theoretical calculations of intercalation complexes with daunomicin(+1) provide the first example in which a drug specifically selects the base pair T·A and prefers it in a particular sequence about the intercalation site. This specificity is in agreement with some experimental results. Problems associated with the interpretation of specificity are discussed in terms of the base, base-pair, and base-sequence resulting from the DNA site and the DNA-drug interactions. T·A specificity is rationalized by noting that the 2′deoxyribo-5′-monophosphate backbone attached to A is slightly more negative than that on the other nucleotides. Hence, a preference exists for binding to the protonated daunosamine (+1) groups. Stereographic projections of daunomycinone and daunomycin(+1) in a bond model and in a space-filling model with steric contours illustrate the results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230111
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  • 6
    Electronic Resource
    Electronic Resource
    Two classes of β-pleated sheet conformation in poly(L-tyrosine): Evidence from solvent perturbation difference spectroscopy (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 1245-1259 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We had earlier observed that the detailed nature of the β-structure adopted by poly(L-tyrosine) depends on molecular weight [Auer, H. E. & McKnight, R. P. (1978) Biochemistry 17, 2798-2805]. It was proposed that shorter molecules form an open, single-layered sheet (class I) and that longer chains fold over to generate at least two layers (class II). In this work, solvent perturbation difference spectroscopy of the chromophoric side chain was applied to gain additional support for the model. Two sample-reference pairs of media, sodium acetate vs sodium chloride and urea vs buffer, were studied. Great care was taken to achieve identical conditions in the sample and reference cells. The factors of importance in executing the experiments are the polypeptide concentration, the degree of side-chain ionization, achievement of the same class of β-conformation, and the absence of significant aggregation. Difference spectra obtained with both solvent pairs have similar features. Low-molecular-weight samples manifest difference bands arising from both ionized and neutral tyrosine side chains, while high-molecular-weight samples yield spectra with contributions primarily from ionized residues. The interpretation of these results is that the class I particle has both ionized and neutral residues exposed to the solvent medium, whereas the class II particle is folded, with neutral residues restricted to the interior of the fold and primarily ionized residues on the outer surfaces exposed to the solvent. Our results, therefore, corroborate the original model.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210617
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  • 7
    Electronic Resource
    Electronic Resource
    Calorimetric study of 2U:1A three-stranded complexes formed between poly(U) and adenine dinucleotides: ApA and diastereoisomers of nonionic adenine dideoxyribonucleoside methyl phosphonate (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2361-2382 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Melting parameters of 2U:1A complexes formed by polyuridylic acid [poly(U)] and three adenine dinucleotides, diribonucleoside monophosphonate ApA and diastereoisomers of dideoxyribonucleoside methyl phosphonate [(dApA)1 and (dApA)2], in 1M NaCl and at a number of dinucleotide concentrations were obtained from differential scanning microcalorimetric data and interpreted in terms of the theory of helix-coil equilibrium in oligonucleotide-polynucleotide systems. The apparent binding constant, 1/cm, at 39°C and melting temperatures, Tm, at 1 × 10-3 M dinucleotide concentration indicate the following order of thermodynamic stability of the complexes: 2 poly(U) · (dApA)2 (2.27 × 103M-1, 44.2°C) 〉 2 poly(U) · (dApA)1 (9.9 × 102M1, 39.2°C) 〉 2 poly(U) · (ApA) (5.9 × 102M-1, 35.8°C). Corresponding calorimetric enthalpies of melting, ΔHm: 13.5, 12.7, and 12.8 kcal/mol (UUA base triplets) were found to be considerably lower than the van't Hoff enthalpies, ΔHapp: 29.4, 16.2, and 16.2 kcal/mol, respectively, evaluated from the dependence of the melting temperatures on dinucleotide concentration. Self-association of dinucleotides and their simultaneous binding as monomers, dimers, and higher-order associated species is suggested as the most probable cause of the differences between ΔHm and ΔHapp values. The differences in thermodynamic properties of the complexes formed by (dApA)1 and (dApA)2 diastereoisomers are discussed in connection with their known conformational properties. The higher and essentially enthalpic stability of the 2 poly(U) · (dApA)2 complex correlates with a lower degree of intramolecular stacking of the (dApA)2 isomer. The hydrophobically enhanced strong self-association of the latter greatly influences the thermodynamics of its complex formation with poly(U) and results in ΔHapp/ΔHm = 2.3.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231117
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  • 8
    Electronic Resource
    Electronic Resource
    High performance liquid chromatography (HPLC) of natural products part VI.For part V, see [1] Sulfoxides of penicillin N and cephalosporin c and their role in biosynthesis of β-lactam antibiotics (1984)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 67 (1984), S. 876-884 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pure pencillin N α-sulfoxide (1) and penicillin N β-sulfoxide (2) were obtained by HPLC and tested as substrates for deacetoxycephalosporin C synthetase (DXCS). Neither one of the sulfoxides was utilized under conditions of conversion of penicillin N (8) to deacetoxycephalosporin C (9). The cephalosporin C α and β-sulfoxides (3 and 4, resp.) were also prepared. Relative stabilities of the sulfoxides 3 and 4 are discussed by interpretation of the 13C-NMR spectra.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19840670329
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  • 9
    Electronic Resource
    Electronic Resource
    High Performance Liquid Chromatography (HPLC.) of Natural Products. III [1]. Isolation of New Tripeptides from the Fermentation Broth of P. Chrysogenum1. Mitt.: [1], 2. Mitt.: [2]. (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 1119-1129 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α-Aminoadipoyl-alanyl-valine, α-aminoadipoyl-serinyl-valine and α-aminoadipoyl-serinyl-isodehydrovaline have been isolated from the fermentation broth of P. chrysogenum. The configuration of α-aminoadipoyl-serinyl-valine has been shown to be L, L, D.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630503
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of L-α-aminoadipyl-L-serinylThe conventional name for a serine residue is seryl. However, since serinyl was used in the previous paper, the term serinyl is retained in the title of this paper.-D-valine, a naturally occuring tripeptide from the fermentation of Penicillium chrysogenum (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2587-2591 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new tripeptide, L-α-aminoadipyl-L-seryl-D-valine has been synthesized by coupling the protected L-seryl-D-valine dipeptide with an appropriately protected L-α-aminoadipic acid ester. The free tripeptide was obtained after treatment with liquid HF and purification by HPLC.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640814
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