Redox-active daunomycin-spin-labeled nucleic acid complexes.

J C Ireland; G T Pauly; E V Bobst; A M Bobst

doi:10.1021/bi00370a023

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Redox-active daunomycin-spin-labeled nucleic acid complexes.

J C Ireland·G T Pauly·E V Bobst·A M Bobst

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Abstract

Interaction studies between daunomycin (DM) and enzymatically spin-labeled nucleic acid duplexes reveal two modes of binding by electron spin resonance (ESR) spectroscopy. At a low drug/nucleotide (D/N) ratio, the drug binds in the intercalative mode with only a slight reduction in base mobility. Saturation in the intercalative mode is achieved at a lower D/N ratio for B' DNA than for B DNA. After full intercalation, further addition of DM seems to destabilize the helix and to allow the formation of redox-active DM stacks complexed to the nucleic acid lattice. These stacks will irreversibly oxidize all the nitroxides covalently bound to the 4- or 5-position of the pyrimidine base. Interactions between DM and spin-labeled single-stranded nucleic acids lead directly to the formation of redox-active complexes, while mixing of the drug with spin-labeled nucleic acid building blocks not incorporated in a nucleic acid lattice causes no ESR signal change. Complete disappearance of the ESR signal of spin-labeled nucleic acids extrapolates to a D/N value which is a constant for a particular lattice system and is independent of spin-labeling content.

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DNA Daunorubicin Electron Spin Resonance Spectroscopy Models, Molecular Nucleic Acid Conformation Oxidation-Reduction Polydeoxyribonucleotides RNA Spin Labels Journal Article

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J C Ireland, G T Pauly, E V Bobst, A M Bobst. 1986-11-04. Redox-active daunomycin-spin-labeled nucleic acid complexes.. https://doi.org/10.1021/bi00370a023

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