Journal of the American Chemical Society 2004-10-13

Lifetime regulation of the charge-separated state in DNA by modulating the oxidation potential of guanine in DNA through hydrogen bonding.

Kiyohiko Kawai, Yasuko Osakada, Tadao Takada, Mamoru Fujitsuka, Tetsuro Majima

Index: J. Am. Chem. Soc. 126(40) , 12843-6, (2004)

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Abstract

A series of naphthalimide (NI)- and 5-bromocytosine ((br)C)-modified oligodeoxynucleotides (ODNs) were prepared, and their lifetimes of the charge-separated states during the photosensitized one-electron oxidation of DNA were measured. Various lifetimes of the charge-separated states were observed depending on the sequence and the incorporation sites of (br)C, and the oxidation potential of G in the (br)C:G base-pair relative to that of G in the C:G base-pair and in the GGG sequence was determined by comparing the lifetimes of the charge-separated states. The change in the cytosine C5 hydrogen to bromine resulted in a 24 mV increase in the oxidation potential of G in the (br)C:G base-pair as compared to that of G in the C:G base-pair, the value of which is comparable to a 58 mV decrease in the oxidation potential of G in the GGG sequence. These results clearly demonstrate that hole transfer in DNA can be controlled through hydrogen bonding by introducing a substituent on the cytosine.