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Formation of polymeric chelate bridges between double-stranded DNA molecules fixed in spatial structure of
Yevdokimov YuM1, V I Salyanov, E Gedig
1Engelhardt Institute of Molecular Biology, The Russian Academy of Sciences, Moscow, Russia.
Abstract:
The formation of cholesteric liquid-crystalline dispersions from DNA-daunomycin complexes in water-salt polyethyleneglycol-containing solutions was investigated. In the case of nonclassical complex formation between DNA and daunomycin (DAU), reactive groups of DAU were used for the formation of polymeric chelate complex with divalent copper ions (-DAU-Cu-...-Cu-DAU-), located between neighboring double-stranded DNA molecules, fixed in spatial structure of liquid-crystalline dispersions. The formation of polymeric chelate complex does not depend upon the sense of helicoidal twist of DNA cholesterics. A many-fold increase in the CD band in the DAU absorption region is specific to this process. A reduction of the divalent copper ions as a result of a redox-process is accompanied by destroying of structure of polymeric chelate complex between DNA molecules and by disappearance of the abnormal CD band in daunomycin absorption region.