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)/isooctane. 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 vmax=4.7×10−3 mmol l−1 min−1 mg−1, Km acid=49.3 mmol l−1, and Km alcohol=47.6 mmol l−1, respectively. CL lipase has also been immobilized in gelatin-containing AOT 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.