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 been used as minireactors for stereoselective resolution of racemic 2-octanol in esterifications with alkanoic acids or in transesterifications with vinyl butyrate. The microstructures were stabilized by the anionic surfactant sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (AOT) or the zwitterionic surfactant soybean lecithin. The enzymes used were commercial lipases from Chromobacterium viscosum or Candida antarctica (SP 525). The incubation temperature was 298.2 K. The enantiomeric excess (e.e.) values were high in all systems studied, but the reaction rates depended on the gel used. In AOT-stabilized 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 reactions. In the hydrogels, the conversion and e.e. values were high, but the reaction rates were low.