N7 Methylation Alters Hydrogen-Bonding Patterns of Guanine in Duplex DNA

N7-Alkyl-2′-deoxyguanosines are major adducts in DNA that are generated by various alkylating mutagens and drugs. However, the effect of the N7 alkylation on the hydrogen-bonding patterns of the guanine remains poorly understood. We prepared N7-methyl-2′-deoxyguanosine (N7mdG)-containing DNA using a transition-state destabilization strategy, developed a novel polβ-host–guest complex system, and determined eight crystal structures of N7mdG or dG...