Candida rugosa lipase has shown to retain catalytic activity in ionic liquids. In this work, enantioselectivity of this enzyme in the esterification of 2-substituted-propanoic acids and 1-butanol is compared in ionic liquids and organic solvents. The role of solvent hydrophobicity (logP), water content and the effect of substituents are evaluated. Optimal water concentration in the reaction media was determined, where the enzyme shows maximal activity and enantioselectivity. Enantioselectivity can be improved when chlorine substituent was replaced by slightly bigger size bromine. Contrary to reactions in common organic solvents, there was no need for purification steps following the reaction in ionic liquids in order to recycle the enzyme. In 1-butyl-3-methyl-imidazolium-hexafluoro-phosphate ([bmim]PF6) and 1-octyl-3-nonyl-imidazolium-hexafluoro-phosphate ([onim]PF6) ionic liquids, C. rugosa lipase could be recycled five times without appreciable activity or enantioselectivity losses.

Thermostability of Candida rugosa lipase in organic solvents and ionic liquids was studied. During our experiments the aim was to determine if the conversion degree and enzyme half-life are changed, i.e. how to tolerate the enzyme the elevated temperature in various solvents. It was found that the enzyme kept its activity and enantioselectivity much better in ionic liquids than in the traditional organic solvents.

An enzymatic reaction in ionic liquids was studied with a special attention to the water content. Water, as a by-product of the esterification by lipase should be removed to enhance the synthesis. Pervaporation was studied for water removal in integrated system.

The possibility to increase the thermostability of the enzyme Candida cylindracea lipase was studied using the medium engineering method. The purpose was to shift the property of the enzyme obtained from mesophilic organism towards thermophilic character and hence widen its application possibilities. Applying the heptane solvent as reaction medium, the relation between the water content of the reaction mixture and the enzyme activity was investigated in the temperature range of 30 degreesC and 50 degreesC. It was found that decreasing the water content of the reaction mixture, the activity of the enzyme was reduced, while its thermostability increased. The slower deactivation of the enzyme was explained by the reduced amount of water present, necessary for the denaturation reactions.

The activity and enantioselectivity of Candida rugosa lipase were investigated in chiral solvents, (−)-, (+)- and racemic carvone, for the resolution of 2-chloro-propionic acid with n-butanol via esterification. The activity of the enzyme studied was about 50% higher in (−)-carvone than in (+)-carvone, however the enantioselectivity was similar.