| Abstract
| - We have characterized the conformational properties of the C8-deoxyguanosine (C8-dG) nucleoside adduct,8-(2"-hydroxyphenyl)-2‘-dG (1), which is a potential biomarker for exposure to phenolic carcinogens. Adduct1 possesses the unique ability to phototautomerize, through an excited-state intramolecular proton transfer(ESIPT) process, to generate its keto form. This tautomerization depends on the presence of an intramolecularhydrogen (H)-bond between the phenolic OH and the imine nitrogen (N7) and has permitted insight into theequilibrium ground states of adduct 1. The results of our studies demonstrate that adduct 1 undergoes anESIPT despite preferring a nonplanar “twisted” conformation that is imposed by the deoxyribose (dR) sugarmoiety. Interestingly, a planar conformation of adduct 1 is also formed in certain aprotic solvents due to theanchoring effect of the intramolecular H-bond. Our results provide a basis for future studies aimed atdetermining the conformations of adduct 1 within DNA that will aid in our understanding of phenol-mediatedcarcinogenesis.
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