Lipase-catalyzed esterification in a reversed micellar reaction system

Abstract

In this work, the lipase-catalyzed synthesis of i-amyl oleate was performed in a reversed micellar system of a cationic surfactant, CPC. The influence of the RM-system constituents on the biocatalysis characteristics (initial esterification rate and conversion extent) was studied and discussed in terms of the RM-structure. The initial water content in the RM-system (the water to surfactant mole ratio, Wo), affected both reaction parameters in a bell-shaped manner, with the maximum depending on the alcohol amount. In general the optimal Wo-values remained between 34 ?40 for a wide range of the initial substrate ratio. The polarity (logP) and the structure of the organic solvent used as the RM-continuum strongly affected the kinetic parameters. A linear function of the initial rate on arg(logP) was established for the alkanes up to n-C1O. The highest rates were measured using a medium of cycle or branched alkanes. The esterification under inhibiting concentrations of the substrates could be intensified by a small change in the initial Wo, thus improving the enzyme RM-accommodation and manipulating the effective concentrations of both substrates around the lipase. In the studied RM-system of 0.115 mol dm-3 CPC, the maximal initial rate of the lipase-catalyzed i-amyl oleate synthesis was found to be limited at ~340 ?mol min-1 g-1.