Role of N1 imino proton in long distance charge transfer through DNA

ORGN 106

Avik Ghosh, gtg232n@mail.gatech.edu and Gary B Schuster. Department of Chemistry and Biochemistry, Georgia Institute of Technology, 770 State Street, Atlanta, GA 30332
Intensive investigation of the oxidation of duplex DNA has shown that loss of an electron generates a radical cation ("hole") that migrates by a hopping mechanism until it is trapped irreversibly in a chemical reaction with H2O or O2, which usually occurs at a guanine or a Gn sequence. The N1 imino proton of guanine radical cation, which is hydrogen bonded to cytidine in a DNA duplex, is thought to play an important role in charge hopping and in these chemical reactions. 5-Fluoro-2'-deoxycytidine (F5dC) is incorporated at specific sites in a DNA oligomer complementary to G to study the effect of N1 imino proton transfer. Results suggest that charge hopping is unaffected; the reaction at the guanines complementary to F5dC slows down considerably.