Osmium Complexation of Mismatched DNA: Effect of the Bases Adjacent to Mismatched 5-Methylcytosine

Abstract

The efficiency of osmium complex formation at 5-methylcytosine in mismatched DNA duplexes is a key point for the design of sequence-specific detection of DNA methylation. Osmium complexation was not observed in fully matched duplexes, whereas the complexation site and efficiency in mismatched duplexes changed depending on the type of 5′-neighboring base of the 5-methylcytosine forming a mismatched base pair. In particular, when the base adjacent to the 5′ side of the mismatched base pair was thymine, a unique “side reaction” was observed. However, the nature of the mismatched base pairs in the reaction site did not influence the selectivity of osmium complex formation with methylated DNA