Enantioselectivity of lipases : Effects of water activity

• Published in: Journal of Molecular Catalysis B: Enzymatic
• Main Authors: Wehtje, Ernst, Costes, David, Adlercreutz, Patrick
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 1997
• Subjects: Biocatalysis and Enzyme Technology; Alcohol resolution; Enantioselective esterification; Lipases; Water activity; Rugosa; Antarc*; Antarctica
• Online Access: https://lup.lub.lu.se/record/3c828615-da85-41e3-9c4f-5d900e591b31; https://doi.org/10.1016/S1381-1177(97)00003-9

The enantioselectivity (E) of lipases in esterifications of secondary alcohols with decanoic acid was studied in organic media. The enantioselectivity of 2-octanol differed greatly among the lipases used. Candida antarctica lipase was extremely selective (E= 9 000) while Candida rugosa lipase was much less selective (E= 1.7). Other enzymes (Lipozyme and lipases from Pseudomonas and Rhizopus arrhizus) had intermediate selectivities. In all cases the enantioselectivity for an enzyme was unaffected by changes in water activity. Different methods of determining the enantioselectivity was used: reactions using single enantiomers as well as racemic mixtures. The effect of water activity on enantioselectivity and the enanatioselectivity values themselves were similar irrespective of the method used. The enantioselectivity of other alcohols were also found to be unaffected by the water activity. The enantioselectivity of Pseudomonas lipase was influenced by the organic solvent. The E decreased with increasing hydrophobicity, from 62 in acetonitrile to 40 in toluene and 33 in hexane. In none of these cases was the enantioselectivity affected by the water activity. However, for Lipozyme and Candida rugosa lipase in toluene a trend of increased E with increasing water activity was observed. In summary it can be stated that the water activity does not generally affect the enantioselectivity of the five lipases tested.