NMR-STUDIES OF A DNA CONTAINING 8-METHOXYDEOXYGUANOSINE

H-1 NMR experiments have been undertaken to elucidate the structural effects of methoxy substitution at the C8 of a deoxyguanosine residue in a self-complementary dodecadeoxyribonucleotide, d(C-G-C-mo8G-A-A-T-T-C-G-C-G), duplex, which has an 8-methoxy-2'-deoxyguanosine (mo8dG) residue at the 4th position. NMR data indicate that the mo8dG residue takes an anti glycosidic conformation in a mo8dG(anti):dC(anti) base-pair structure in a B-form duplex. The thermal stability of the duplex is reduced, but the overall structure is much the same as that of the unmodified d(C-G-C-G-A-A-T-T-C-G-C-G) duplex.