The NMR studies of substituent effects on the N-H...N hydrogen bond in duplex DNA using 2'-deoxynebularine and 15N labeled 5-substituted-2'-deoxyuridine base pairs.

The effects of substitutions on various NMR parameters, which may influence the hydrogen bond strengths of Watson-Crick base pairs, were investigated for DNA dodecamers containing 5-substituted-2'-deoxyuridine derivatives and 2'-deoxynebularine in the oligomers, 5'-d(CGCGNA TX CGCG)-3'; where N and X are 2'-deoxy nebularine and [N3-(15)N]-2'-deoxyuridine derivatives. The substitution effects on NMR parameters were linearly correlated with the pKa values of the 2'-dexoyuridine derivatives.