Kinetic study of the enantioselective hydrolysis of a meso-diester using pig liver esterase

Abstract

A kinetic study of the hydrolysis of the diester dimethyl cis-cyclohex-4-ene-1,2-dicarboxylate, to the (1S,2R)-monoester, catalysed by the enzyme Pig Liver Esterase (PLE) was performed. The effects of the most relevant parameters that in¯uence the enzymatic conversion were studied, such as pH, temperature and concentration of substrate and reaction products. It was concluded that the pH at which the enzyme exhibits a maximum activity is pH 7. At 25°C PLE presents a better long-term stability and enantioselectivity than at higher temperatures, although the reaction rate is slower. The kinetic results obtained are well described by the Michaelis±Menten equation, although a slight deviation to this model was observed for low substrate concentrations. Methanol, a co-product of the enzymatic hydrolysis, was found to act as a non-competitive inhibitor of the reaction. The Michaelis± Menten parameters were determined and a comprehensive kinetic model, which already accounts for methanol inhibition, is presented.

Scale-Up of a Recombinant Pig Liver Esterase-Catalyzed Desymmetrization of Dimethyl Cyclohex-4-ene-cis-1,2-dicarboxylate

“…The other enantiomer, (1 S ,2 R) -monoester 2a , was repeatedly synthesized via a pig liver esterase-catalyzed reaction. Unfortunately the reaction is not entirely enantioselective, and a lower enantiomeric excess of 80–97% ee was obtained (Scheme ). ,− The reduced enantioselectivity results from the presence of several parallel hydrolytic reactions, each independently catalyzed by different isoenzymes of pig liver esterase. The products of highly enantioselective isoenzymes are hereby mixed with products from less selective enzymes.…”

Kinetic and modeling of radiolytic decomposition of antibiotics

“…The radiolytic decomposition of a given antibiotic can be described using the Monod equation (equation 3), frequently used in enzyme kinetic studies [25,26,27,28,29,30].…”

Enantioselective Hydrolysis of a meso-Diester Using Pig Liver Esterase in a Two-Phase Stirred Tank Reactor

“…The differential material balance for the diester in the aqueous film of thickness δ aq can be written as where C A(aq) is the diester concentration in the aqueous film, D A(aq) is the diffusion coefficient of the diester in the aqueous phase, and r A(aq) ≡ r A ( C A(aq) , C B(aq) ) is the reaction rate in the aqueous film, expressed as consumption of A. As shown by Sousa et al, r A is well described by a Michaelis−Menten kinetics with noncompetitive inhibition by methanol: The values of the kinetic parameters are V max = 1.28 × 10 - 8 (M enz unit -1 s -1 ) × enz unit, K M = 0.044 M, and K I = 1.93 M. Taking into consideration the stoichiometry of the enzymatic reaction, the concentration of methanol, C I , is equal to the concentration of monoester, C B .…”

“…The differential material balance for the diester in the aqueous film of thickness δ aq can be written as where C A(aq) is the diester concentration in the aqueous film, D A(aq) is the diffusion coefficient of the diester in the aqueous phase, and r A(aq) ≡ r A (C A(aq) ,C B(aq) ) is the reaction rate in the aqueous film, expressed as consumption of A. As shown by Sousa et al, 11 r A is well described by a Michaelis-Menten kinetics with noncompetitive inhibition by methanol:…”