Lipase-catalysed esterification reaction in an organic solvent: Comparison between free and immobilised biocatalysts

Abstract

The ability of Mucor miehei lipase to catalyse the esterification reaction between oleic acid and ethanol in a nearly anhydrous organic solvent has been investigated. First, a soluble lipase form was obtained by partial purification of a brute enzymatic solution. The esterification activity of the lipase and its stability in n-hexane were assayed, and the influence of water content on activity was studied. Optimal reaction conditions were obtained for 10 % weight of water/weight of purified enzyme. The reaction kinetics were determined and they were found to fit a Ping-Pong Bi Bi mechanism in which inhibition by excess of ethanol has been identified. The catalytic properties of the soluble form of the enzyme were compared to those previously obtained for the immobilised lipase. Both forms showed the same mechanism, although some differences were found, concerning the stability, values of the kinetic constants and influence of water content.