Purification and catalytic properties of novel enantioselective lipase from Acinetobacter sp. ES-1 for hydrolysis of ( S)-ketoprofen ethyl ester

Abstract

A novel enantioselective lipase from Acinetobacter sp. ES-1 exhibiting an excellent enantioselectivity for ( S)-ketoprofen ethyl ester was purified to homogeneity using hydrophobic interaction chromatography. The molecular weight and p I value of the purified enantioselective lipase were 32 kDa and 6.2, respectively, and the optimal temperature and pH were 40 °C and 7.0. The activity was enhanced 1.5-fold in the presence of Ca 2+ ions, and showed the substrate specificity preferably for a medium-chain length, such as triacylglycerides and p-nitrophenyl esters. The N-terminal amino acid residue was A–V–R–S–I–D–G–L–A–I–N–Q–S–A, and no homology was found among other known lipases, indicating a novel type enzyme. The enantioselective hydrolysis of ( R, S)-ketoprofen ethyl ester to optically pure ( S)-ketoprofen was carried out in the aqueous phase reaction system achieving an high enantiomeric excess of 0.99 and conversion yield of 0.49 after 72 h.