EVIDENCE FOR A(-G(SYN) MISMATCHED BASE-PAIRING IN D-GGTAAGCGTACC()(ANTI))

Two-dimensional MMR spectroscopy has been used to study the structure and hydrogen bonding scheme of A:G mismatched base pairing in d-GGTAAG CGTACC at pH 5.8, Under the conditions of our study, the molecule form s a B-DNA helix, with the mismatched bases in the A(+)(anti)-G(syn) co nformation, The adenosine exists in the protonated form, The NOESY spe ctrum in 90% H2O + 10% (H2O)-H-2 has been used to assign all observabl e imino and amino protons including those involved in the A(+)(anti)-G (syn) base pair, Both the proton donors in the A:G mismatched inter-ba se hydrogen bonding are situated on adenosine.