Transient-phase and steady-state kinetics of lipase-catalyzed ester hydrolysis.

An experimental study has been made of both the steady-state and the transient-phase (presteady-state) kinetics of the hydrolyses of several saturated aliphatic esters of p-nitrophenol catalyzed by wheat germ lipase. The analysis of the presteady- 1 Presented in part at the 173rd ACS National Meeting, New Orleans, L.A., U.S.A., March 20--25, 1977. 2 Correspondence should be addressed to M.H. Sadar, E.S.D., E.H.C., Health and Welfare Canada, Tunney's Pasture, Ottawa, Ontario, Canada, K1A OL2. 3 Department of Chemistry, University of Ottawa, Ottawa, Ontario, Canada. state part revealed two transients indicating that lipase-catalyzed reactions proceed via a two-intermediate mechanism suggested for other esterases. The possibility of more than one species of the enzyme engaged in catalytic activity is discussed and a reaction mechanism scheme is proposed accordingly.