Kinetic studies of lipase-catalyzed esterification in water-in-oil microemulsions and the catalytic behavior of immobilized lipase in MBGs

The esterification kinetics of octanoic acid with 1-octanol, catalyzed by Candida lypolytical (CL) lipase, was studied in water-in-oil microemulsions formed by water/bis-(2-ethylhexyl)sulfosuccinate sodium (AOT)/isooetane. Kinetic studies showed that the reaction follows a Ping-Pong Bi Bi mechanism with inhibition by excess of 1-octanol. The values of all apparent kinetic parameters were determined to be nu (max) = 4.7 x 10 (- 3) mmol l (- 1) min (- 1) mg (- 1), K-m acid = 49.3 mmol l (- 1), and K-m alcohol = 47.6 mmol l (- 1), respectively. CL lipase has also been immobilized in gelatin-containing ACT microemulsion-based organogels (MBGs) with retention of catalytic activity. These lipase-containing MBGs were proved to be a novel solid-phase catalyst for use in apolar organic solvents. The behavior of this novel, predominantly hydrophobic matrix as an esterification catalyst was also examined. (C) 2001 Elsevier Science B.V. All rights reserved.