Modified DNA Bearing 5(Methoxycarbonylmethyl)‐2′‐deoxyuridine: Preparation by PCR with Thermophilic DNA Polymerase and Postsynthetic Derivatization

A thymidine analogue bearing a methyl ester at the C5 position was accepted as a substrate by the thermophilic family B DNA polymerases, KOD Dash, Pwo, and Vent(exo−), to form the corresponding PCR product, but not by the thermophilic family A DNA polymerases, Taq, Tth, and T7 thermosequenase. Modified DNA containing this analogue was prepared by PCR on a large scale with KOD Dash DNA polymerase and 5(methoxycarbonylmethyl)‐2′‐deoxyuridine 5′‐triphosphate as a substrate. The methyl ester of the modified DNA was further allowed to react with tris(2‐aminoethyl)amine or histamine by an ester–amide exchange reaction to form the corresponding derivatized DNA bearing a tris(2‐aminoethyl)amine or histamine moiety. Hydrolysis of the methyl ester of the modified DNA gave a functionalized DNA bearing an anionic carboxyl group. The derivatized DNA could act as a template for the PCR with KOD Dash DNA polymerase and the natural 2′‐deoxythymidine 5′‐triphosphate or the modified thymidine analogue as a substrate. The postsynthetic derivatization of the modified DNA may expand the variety of structurally modified DNA produced by PCR.