The synthesis of 2′-bromoacetamido-2′-deoxyuridine and its reaction with ribonuclease A

Bovine pancreatic ribonuclease A reacts with 2′-bromoacetamido-2′-deoxyuridine at pH 5.5 and 25°C rapidly and with absolute specificity. The single product formed has been tentatively identified as N-3-(2′-carboxamidomethyl-2′-deoxyuridinyl)-histidine-12-ribonuclease A. The reaction exhibits binding kinetics, K m being equal to 0.11 M for the nucleoside derivative and k 3 equal to 57 × 10 −4 sec −1. The reaction of 2′-bromoacetamido-2′-deoxyuridine with ribonuclease A occurs at a rate which is approximately 4000 times faster than its corresponding reaction with L-histidine.