A molecular orbital study on the effects of substituents on the proton transfer from Ser-195 to His-57 in the hydrolysis of .ALPHA.-chymotrypsin.

Publisher Website
Google Scholar
Abstract
From the results of molecular orbital study on the effects of substituents on the proton transfer from Ser-195 to His-57 in the charge relay system of .alpha.-chymotrypsin, an acylation step is proposed. The carbonyl C of the substrate approaches to the oxygen of Ser-195 in the charge relay system. After the proton of Ser-195 is transferred to N.delta.2 of His-57 by the trigger of the interaction between the oxygen of Ser-195 and the carbonyl C of the substrate, the oxygen of Ser-195 covalent-bonds with the carbonyl carbon of the substrate. Acyl-Ser-195 rotates 120 degrees around the serine C.alpha.-C.beta. bond. The rotation of acyl-Ser-195 must be accompanied with the deeper movement of the aromatic part of the substrate in the pocket of .alpha.-chymotrypsin. A significant role in accelerating the proton transfer from Ser-195 to His-57 was played by the interaction between the oxygen of Ser-195 and carbonyl C of substrate and not by 2 hydrogen bonds between the carbonyl oxygen and the backbone-NH-groups of Gly-193 and Ser-195.

This publication has 1 reference indexed in Scilit: