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  • 1
    Electronic Resource
    Electronic Resource
    An elastic model of the large-scale structure of duplex DNA (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 609-623 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general model for the large-scale, time-independent structure of duplex DNA is developed based on elastic considerations. The general conditions of elastic equilibrium are given. These equations are solved for the equilibrium shape of stressed duplex DNA, based on the assumption that the double helix behaves mechanically as a symmetric, linearly elastic rod. It is shown that, in general, two orders of superhelicity will arise at equilibrium. Several possible applications of this approach to the supercoiling of closed circular DNA are described.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180310
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics of reactions involving DNA containing stress-induced single-stranded regions (1980)
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 2143-2164 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theoretical kinetics are analyzed for reactions between torsionally stressed DNA and another compound which reacts at different rates with portions of the substrate molecule which are in different conformational states. These reactions are assumed to obey Michaelis-Menten kinetics, so no cooperative effects occur. The DNA is regarded as being susceptible to a stress-induced local conformational transition as described recently by Benham. Briefly, alterations in torsional stress consequent on superhelicity effectively change the relative concentrations of the two conformational states of the substrate, thereby influencing the course of the reaction. This theory is developed for transition between the B-form helix and the single-stranded, random-coil states. To illustrate the influence of posited stress-induced melting on kinetics, calculations are made on simple models of two biochemical phenomena. First, the variations in initial nicking rates of single-strand-specific endonucleases with substrate superhelicity are interpreted as arising from changes in the concentration of (stress-induced) single-stranded binding sites. Second, the observed dependence of the transcription rate of RNA polymerase core enzyme on substrate superhelicity is interpreted in terms of a model in which the rate-limiting step in the initiation event is the formation of a complex between the enzyme and a single-stranded region. Related experimental results are shown to be qualitatively consistent with the suggestion that sufficiently supercoiled DNA contains locally melted regions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1980.360191202
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  • 3
    Electronic Resource
    Electronic Resource
    Geometry and mechanics of DNA superhelicity (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 2477-2495 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper analyzes the elastic equilibrium conformations of duplex DNA constrained by the constancy of its molecular linking number, Lk. The DNA is regarded as having the mechanical properties of a homogeneous, linearly elastic substance with symmetric cross section. Integral representations of the writhing number Wr and of Lk are developed, in terms of which the equilibria are given as solutions to an isoperimetric problem. It is shown that the Euler angles defining equilibrium conformations must obey equations identical to those governing unconstrained equilibria. A scaling law is developed stating that molecules supercoiled the same amount ΔLk will have geometrically similar elastic equilibria regardless of their length. Thus, comparisons among molecules of properties related to their large-scale tertiary structure should be referred to differences in ΔLk rather than to their superhelix densities. Specific conditions on the elastic equilibrium conformations are developed that are necessary for ring closure. The equilibrium superhelical conformations accessible to closed-ring molecules are shown to approximate toroidal helices. Questions relating to the stability and nonuniqueness of equilibria are treated briefly. A comparison is made between these toroidal conformations and interwound configurations, which are shown to be stable, although they are not equilibria in the present sense. It is suggested that entropic factors are responsible for favouring the toroidal conformation in solution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360221112
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  • 4
    Electronic Resource
    Electronic Resource
    The role of the stress resultant in determining mechanical equilibria of superhelical DNA (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 9-15 
    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.360260105
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis, Structure, and Antimalarial Activity of Some Enantiomerically Pure, cis-fused cyclopenteno-1,2,4-trioxanes (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 647-662 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two pairs of enantiomerically pure cis-fused cyclopenteno-1,2,4-trioxanes (7, ent-7 and 8, ent-8) are prepared (Schemes 1-3). Their identities are established by dye-sensitized photo-oxygenation of ent-7 and 8, ent-8 to the allylichydroperxides, reduction to the corresponding alcohols, and conversion to the (1S)-camphanates (Scheme 4), the structures of which are determined by X-ray analysis. The dynamic properties of ent-7 are investigated by NMR spectroscopy and PM3 calculations. Evidence for an easily accessible twist-boat conformation is obtained. The in vitro and in vivo antimalarial activities of 7, ent-7,8, and ent-8 as well as those of the racemic mixtures are evaluated against Plasmodium falciparum, P. berghei, and P. yoelii. No correlation is observed between configuration and activity. Racemates and pure enantiomers have commensurate activities. The mode of action on the intraerythrocytic parasite is rationalized in terms of close docking by the twist-boat conformer of the trioxane on the surface of a molecule of heme, single-electron transfer to the O—O σ* orbital, and scission to the acetal radical which then irreversibly isomerizes to a C-centered radical, the ultimate lethal agent (Scheme 5).
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780312
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of cholesterol, cholesterol-5,6-epoxides and cholestane-3β,5α,6β-triol in nipple aspirates of human breast fluid by gas chromatography/mass spectrometry (1987)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1987), S. 335-338 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method has been developed for the quantitative determination of cholesterol and three of its major oxidative metabolites (the 5α,6α-epoxide, the 3β,5α,6β-triol, and the 5β,6β-epoxide) in a single sample of human breast fluid (2-50 μl), using gas chromatography/mass spectrometry with selected ion monitoring. High specificity and reliable quantification is achieved by the use of the inverse stable isotope dilution method, employing deuterium-labeled variants of the compounds as internal standards.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200140707
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  • 7
    Electronic Resource
    Electronic Resource
    Highly branched radial block copolymers via dendritic initiation of aliphatic polyesters (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2793-2798 
    Details
    ISSN: 0887-624X
    Keywords: highly branched radial block copolymers ; dendritic initiation ; alipatic polyesters ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Living ring opening polymerization of ε-caprolactone initiated from the numerous chain-end hydroxymethyl groups of the analogous dendrimeric and hyperbranched polyesters derived from 2,2-bis(hydroxymethyl) propionic acid is described. By controlling the size of the dendritic macromolecule and the molar ratio of ε-caprolactone, a variety of highly branched radial block copolymers are obtained. Comparison of the results obtained for the dendrimeric and hyperbranched initiators demonstrates that the reactivity of the chain-end hydroxymethyl groups in the dendrimer are significantly greater than in the isomeric hyperbranched case. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2793-2798, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    A versatile and efficient synthesis of alkoxyamine LFR initiators via manganese based asymmetric epoxidation catalysts (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2161-2167 
    Details
    ISSN: 0887-624X
    Keywords: alkoxyamine ; living free radical polymerizations ; asymmetric epoxidation ; Jacobsen's catalyst ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Intramolecular cyclization in hyperbranched polyesters (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1627-1633 
    Details
    ISSN: 0887-624X
    Keywords: hyperbranched macromolecule ; polyester ; focal point groups ; intramolecular cyclization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of monomer structure and catalyst on the synthesis of hyperbranched polyesters based on 4,4-(4′-hydroxyphenyl)pentanoic acid has been examined. The nature of the ester group and the catalyst have a significant effect on the molecular weight of the hyperbranched polyester but do not effect the degree of branching for these materials. The fate of the single ester group at the focal point of these hyperbranched macromolecules is probed by the synthesis and polymerization of 13C labeled methyl 4,4-(4′-hydroxyphenyl)pentanoate. Comparison of the molecular weights determined by 1H- or 13C-NMR spectra with those determined by osmometry suggest that intramolecular cyclization does not occur to a significant extent in these systems. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1627-1633, 1997
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    The absolute configuration of the enantiomers of 6-chloro-9-(4′-diethylamino-1′-methylbutyl)-amino-2-methoxyacridine (quinacrine) (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 436-437 
    Details
    ISSN: 0899-0042
    Keywords: stereochemistry ; quinacrine ; enantiomers ; enantioselectivity ; circular dichroism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Absolute configurations have been assigned to the enantiomers of the antimalarial drug quinacrine dihydrochloride. Condensation of (-)-(R)-4-amino-1-diethylaminopentane (from L-glutamic acid) with 6,9-dichloro-2-methoxyacridine gave (-)-(R)-6-chloro-9-(4′-diethylamino-1′-methylbutyl) amino-2-methoxyacridine [(-)-(R)-quinacrine] while (+)-(S)-quinacrine was obtained from the enantiomeric diamine.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030510
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