E. M. Crook

The kinetic analysis of hydrolytic enzyme catalyses: Consequences of non-productive binding.

for which the evidence in favour of this type d kinetic mechanism is particularly convincing is papain (EC 3.4.4.10). Thus Lowe and Williams [8] convincingly demonstrated that the papain-catalysed hydrolysis of methyl thionohippurate invoives the formation of an acyl-enzyme intermediate in which the acyl moiety of the substrate is linked to the active centre cysteine residue by a thiol ester bone. One of the major problems in the study of enzyme catalyses described by eq. (1) is the isolation of values for the first order rate constants for both acylation (k2) and deacylation (k3) or at least the assessment of their relative magnitudes. The recent approaches to the solution of this problem by Whitaker and Bender [9] and by Sluyterman [lo] yield conflicting results when applied to papain-catalysed hydrolyses. Whitaker and Bender determined k2 and k3 separately for the papain-catalysed hydrolysis of BAEE * and