Effect of pressure on the pre-steady-state kinetics of the hydrolysis of anilide substrates catalyzed by alpha-chymotrypsin.

The pre-steady-state of the hydrolysis of succinyl-L-alanyl-L-alanine p-nitroanilide (SA2pNA) and succinyl-L-alanine p-nitroanilide (SApNA) catalyzed by alpha-chymotrypsin in Tris buffer solution was measured up to 1.5 kbar at 25 degrees C. The pressure dependence of the formation of tetrahedral intermediate from the Michaelis complex on the rate constant (k1) gave activation volumes, delta V1 not equal to, of -33 +/- 2 cm3 X mol-1 for SA2pNA and -30 +/- 2 cm3 X mol-1 for SApNA. The reaction mechanism of alpha-chymotrypsin is discussed in terms of the activation volumes.