STUDIES OF THE INTERACTIONS OF CHIRAL RUTHENIUM(II) COMPLEXES WITH DNA.
Item
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Title
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STUDIES OF THE INTERACTIONS OF CHIRAL RUTHENIUM(II) COMPLEXES WITH DNA.
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Identifier
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AAI8801699
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identifier
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8801699
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Creator
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DANISHEFSKY, AVIS TCHIYA.
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Contributor
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Jacqueline K. Barton
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Date
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1987
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Biochemistry
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Abstract
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We have investigated the interactions of chiral polypyridyl complexes of ruthenium(II) with DNA. The ultimate goal of these studies is to develop these, or similar complexes, as probes or modifiers of DNA with particular conformational or sequence specificities. Chiral complexes are employed because the relative affinity of two enantiomers can reflect the conformation of the helical DNA. Moreover, the well characterized spectroscopic characteristics of the ruthenium(II) complexes provide a handle by which the interactions of these molecules with DNA can be monitored.;Enhancement of the emission of Ru(1,10-phenanthroline){dollar}\sb3\sp{lcub}2+{rcub}{dollar} and Ru(4,7-diphenylphenanthroline){dollar}\sb3\sp{lcub}2+{rcub}{dollar} is observed upon binding to DNA. Emission titrations of Ru(phen){dollar}\sb3\sp{lcub}2+{rcub}{dollar} with calf thymus DNA illustrate that greater enhancement is observed for the {dollar}\Delta{dollar} enantiomer than for the {dollar}\Lambda{dollar} enantiomer, consistent with our model of an intercalative mode of binding. The degree of enantioselectivity observed was dependent on DNA base composition, which may reflect the different modes of binding of Ru(phen){dollar}\sb3\sp{lcub}2+{rcub}{dollar} to these various sites as well as differences in structures of the binding sites.;We have also studied interactions of the complex, Ru(phen){dollar}\sb2{dollar}Cl{dollar}\sb2{dollar} with DNA. Coordination of ruthenium(II) to DNA leads a sequence selectivity to the binding as well as a greater degree of stability of the bound adduct as compared to that of the tris chelate complex. Binding studies indicate a preference for G{dollar}\cdot{dollar}C containing sequences. A binding preference for the {dollar}\Lambda{dollar} enantiomer was observed in most cases. Of the polynucleotides examined, only the alternating polymer poly(dG-dC) {dollar}\cdot{dollar} poly(dG-dC) displayed a binding preference for the {dollar}\Delta{dollar} enantiomer. Similar degrees of enantioselectivity in binding were observed for poly(dG){dollar}\cdot{dollar}poly(dC) and calf thymus DNA suggesting that the binding sites on these two polynucleotides are structurally similar. A model of the bound adduct is proposed based on these observations and on spectroscopic data.;Photochemical reactions of the ruthenium(II) complexes with DNA have also been observed. Irradiation of Ru(phen){dollar}\sb2{dollar}Cl{dollar}\sb2{dollar} in the presence of DNA increases the rate of binding, though the mode of binding appears to be similar to that of the thermal reaction. Photocleavage of DNA in the presence of Ru(phen){dollar}\sb3\sp{lcub}2+{rcub}{dollar} and Ru(phen){dollar}\sb2{dollar}Cl{dollar}\sb2{dollar} has also been observed.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biochemistry
