Deoxyribosyl Transfer Catalysis with trans‐N‐Deoxyribosylase

Abstract

Kinetic studies were carried out in order to investigate the enzymic mechanism of a 215-fold-purified purine(pyrimidine) nucleoside:purine(pyrimidine) deoxyribosyl transferase fraction from Lactobacillus helveticus. A variety of natural deoxyribonucleosides and bases were used as substrates. Initial velocity, product inhibition and isotopic exchange studies are consistent with a ping-pong bi-bi mechanism. The kinetic parameters are used to show that this fraction is free from any contamination by a specific purine nucleoside:purine deoxyribosyl transferase also found in the same strain of L. helveticus.