Modeling the effect of free water on enzyme activity in immobilized lipase-catalyzed reactions in organic solvents

Abstract

The influence of water content on the lipase-catalyzed acidolysis of triolein (glycerol-trioleate, TO) and caprylic acid (CA) in hexane, using an immobilized enzyme was studied. An adequate water content (R W ) ranged from near zero to 0.1 g of water/g of dry enzyme. Over these values there was a decrease in the rate of incorporation of CA into triglyceride. This decrease was attributed to the progressive flooding of the carrier's pores, in which the enzyme was immobilized. The flooding reduced the number of the enzyme molecules at the water-hexane interface and therefore, hindered the accessibility of the hydrophobic substrates (TO and CA) to the enzyme. A simple physical model based on a characterization of the immobilized enzyme particle by mercury porosimetry was developed. The model agreed well with both the experimental data and the prior published data. The model may partly explain the observed inhibition when using low molecular weight alcohols and carboxylic acids in immobilized lipase-catalyzed processes.

Kinetic Study for the Ethanolysis of Fish Oil Catalyzed by Lipozyme^® 435 in Different Reaction Media

“…Camacho et al 21 proposed a mechanistic model based on the elementary reactions that may occur in the process. In this work, a simple model similar to the one proposed by Oliveira et al 22 , has been considered.…”

Influences of operating conditions on biocatalytic activity and reusability of Novozym 435 for esterification of free fatty acids with short-chain alcohols: A case study of palm fatty acid distillate

“…Previously, it was suggested that the agglomeration of water might flood the enzyme pores, causing decreases in the reaction rates [30]. In this study, it was also shown that the presence of water at 4-5 % in ethanol cause some negative effects on the reusability of the biocatalyst.…”

Identification and Quantitation of Reaction Intermediates and Residuals in Lipase-Catalyzed Transesterified Oils by HPLC

“…The initial low conversion of the TAG and relative high amount of unreacted TAG quantified in the transesterified oils during the initial segment of the reaction may be due to a myriad of factors, such as initial delay in the transesterification reaction and may be due to minimal mixing and dispersion of the alcohol with oil, poor solvation, or low miscibility of TAG in the alcohol creating a two-phase/heterogeneous system, the deactivation effect of the polar ethanol on the enzyme, interfacial action of lipase, and the nature of lipase catalysis in non-aqueous media [27][28][29][30][31][32].…”