5-(alpha-Bromoacetyl)-2'-deoxyuridine 5'-phosphate: an affinity label for thymidylate synthetase.

5-(alpha-Bromoacetyl)-2'-deoxyuridine 5'-phosphate (1) is an active-site-directed irreversible inhibitor of thymidylate synthetase from Lactobacillus casei. Analysis of the rate of inactivation of the enzyme in the presence of substrate confirmed the intermediate formation of a reversible enzyme-inhibitor complex.