Kinetics and mechanism of a reaction catalyzed by PST‐01 protease from Pseudomonas aeruginosa PST‐01

The initial rates of carboxybenzoyl‐alanyl‐ l ‐leucyl‐amide ( Z ‐ l ‐Ala‐ l ‐Leu‐NH 2 ) synthesis from carboxybenzoy l ‐ l ‐alanine ( Z ‐ l ‐Ala) and l ‐leucineamide ( l ‐Leu‐NH 2 ) and Z ‐ l ‐Ala‐ l ‐Leu‐NH 2 hydrolysis in a homogeneous dimethyl sulfoxide‐aqueous buffer solution [1:1 (v/v)] system catalyzed by PST‐01 protease from Pseudomonas aeruginosa were measured under a wide range of Z ‐ l ‐Ala, l ‐Leu‐NH 2 and Z ‐ l ‐Ala‐ l ‐Leu‐NH 2 concentrations. The initial rates of the synthetic reaction, in which Z ‐ l ‐Ala‐ l ‐Leu‐NH 2 was produced from Z ‐ l ‐Ala and l ‐Leu‐NH 2 , were inhibited by the substrates. Furthermore, the initial rates of the synthetic reaction were not inhibited by the product Z ‐ l ‐Ala‐ l ‐Leu‐NH 2 , and those of the hydrolytic reaction were inhibited by Z ‐ l ‐Ala and l ‐Leu‐NH 2 . All the initial rate data of the synthetic and hydrolytic reactions were well correlated with the rate equation derived based on the proposed reaction scheme. © 2004 Wiley Periodicals, Inc.