Temperature-jump Studies on the Interaction of Benzeneboronic Acid with Chymotrypsinogen
1976 年 80 巻 3 号 p. 491-495
詳細
1976 年 80 巻 3 号 p. 491-495
The interaction of chymotrypsinogen A with benzeneboronic acid (BBA), a transition state analog inhibitor of serine proteases, was investigated by the temperature-jump method using pH indicators. It was found that 1/τ is dependent on BBA concen-tration, in contrast to the case of the a-chymotrypsin [EC 3.4.21.1]-BBA system in which 1/τ is independent of BBA concentration. By examination of the pH depend-ences of the kinetic parameters, the acid dissociation behavior of His 57 in chymotry-psinogen, chymotrypsinogen-trigonal BBA complex and chymotrypsinogen-tetrahedral BBA complex was analyzed. The kinetic deuterium isotope effect was also examined and found to occur principally on the acid dissociation constants. The state of the catalytic residues in the zymogen molecule is discussed based on these results.
