Positive cooperativity of the specific binding between Hg2+ ion and T:T mismatched base pairs in duplex DNA

► Hg2+ specifically bound with the T:T mismatched base pair at 1:1 molar ratio. ► The binding constant between Hg2+ and the T:T mismatched base pair was 106 M−1. ► The binding constant was larger than those for nonspecific metal-DNA interactions. ► The binding constant for the second Hg2+ was larger than that for the first Hg2+. ► The positive cooperative binding was observed between Hg2+ and multiple T:T.