proceed via the Ping-Pong mechanism
نویسندگان
چکیده
Acyl-transfer catalysed by y-glutamyltranspeptidase from bovine kidney was studied using y-Land y-D-Glu-p-nitroanilide as the donor and GlyGly as the acceptor. The transfer of the y-Glu group to GlyGly was shown to be accompanied by transfer of the y-Glu group to water (hydrolysis). The results were compared with acyl-transfer catalysed by the representative serine protease, a-chymotrypsin. The main difference between the kinetic mechanism of the acyl-transfer reactions catalysed by these enzymes, which contain an active-site serine and form an acyl-enzyme intermediate but belong to different enzyme classes, was found to consist in the role of the enzyme-donor-acceptor complex. This complex is not formed at any acceptor concentrations in the acyltransfer reactions catalysed by the serine proteases. In contrast,
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