Synthetic inhibitors of Escherichia coli, calf thymus, and Ehrlich ascites tumor thymidylate synthetase

In a study of active site binding the inhibition of thymidylate synthetase derived from Escherichia coli, calf thymus, and Ehrlich ascites tumor was examined using eight inhibitors. 5-Substituted 2'-deoxyuridine 5'-phosphate analogues used in this study are the hydroxymethyl, methoxymethyl, benzyloxymethyl, formyl, acetyl, allyl, and two potential active site alkylating substituents: 2,3-oxypropyl and the azidomethyl analogues. All compounds were competitive with the substrate, 2'-deoxyuridine 5'-phosphate; the most potent inhibitor was 5-formyl-dUMP (Ki = 0.1, 0.09, and 0.08 muM for the respective enzyme). The 5-hydroxymethyl, 5-benzyloxymethyl, and 5-azidomethyl derivatives of dUMP showed some differential inhibition; these compounds were two to three times more active against the ascites tumor enzyme than against the thymus enzyme.