Influence of pH on the Conformation and Stability of Mismatch Base-Pairs in DNA
J. Mol. Biol. 212 (3), 437-440, 1990.
Abstract
A series of self-complementary dodecanucleotide duplexes containing two symmetrically disposed mismatches have been studied by pH-dependent, ultraviolet light melting techniques. The results indicate that A · C, and C · C mismatches are strongly stabilized by protonation and that the degree of stabilization of the A · C mismatch depends greatly on the flanking bases. In one case, a duplex containing two A · C mismatches is more stable than the native sequence below pH 5.5. The G · A mismatch displays conformational flexibility, with a protonated G(syn) · A(anti) base-pair occurring in certain base stacking environments but not in others. The A · A and T · C mismatches are not stabilized at low pH. These solution studies correlate well with predictions based on X-ray crystallographic data.