Enzyme catalysis in different gelatin gels

Enzymes in microemulsions, liposomes, aqueous monomer surfactant solutions or pure water have been entrapped in gelatin-based gels. These gels have be en used as minireactors for stereoselective resolution of racemic 2-octanol in esterifications with alkanoic acids or in transesterifications with vin yl butyrate. The microstructures were stabilized by the anionic surfactant sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (AOT) or the zwitterionic surfa ctant soybean lecithin. The enzymes used were commercial lipases from Chrom obacterium viscosum or Candida antarctica (SP 525). The incubation temperat ure was 298.2 K. The enantiomeric excess (e.e.) values were high in all sys tems studied, but the reaction rates depended on the gel used. In AOT-stabi lized and in ethanol-free lecithin-stabilized gels the conversion was close to 0.45. However, in the ethanol-containing lecithin gels, the conversion was lower and decreased with increased ethanol content, due to competing re actions. In the hydrogels, the conversion and e.e. values were high, but th e reaction rates were low.