Complex formation between a DNA duplex and lipid-like spermine derivatives: hydrophobic protection of DNA from one-electron oxidation.
The one-electron oxidation of DNA leads to formation of a nucleo-base radical cation that can migrate to a distant site where it is trapped by H2O or O2 to form a "damaged" guanine that is revealed as strand cleavage when the irradiated sample is treated with piperidine. We prepared a series of alkyl-substituted spermine derivatives and assessed their effect on the oxidative reactions of DNA induced by photoexcitation of a covalently linked anthraquinone derivative. The spermine compounds are polycations and bind nonselectively to DNA. When the spermine derivative is substituted with C8 alkyl chains, it shows lipid-like properties. The reaction of the radical cation at guanine is affected by this lipid-like spermine. The distance dependence of the migration process becomes weaker, and the efficiency of strand cleavage is reduced. These results are attributed to the formation of a hydrophobic layer on the DNA that restricts access of H2O to the nucleo-base radical cation.
Cao
Huachuan
H
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Schuster
Gary B
GB
D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D004583:Electrons; D004591:Electrophoresis, Polyacrylamide Gel; D008055:Lipids / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry; D013050:Spectrometry, Fluorescence; D013096:Spermine / Q000737:chemistry*
D008055:Lipids; D013096:Spermine; D004247:DNA