Preparation and esterification activity of poly[(N-propionyl)iminoethylene] modified lipase from Candida cylindracea

Candida cylindracea lipase was modified with a carboxylic acid-terminated polymer of poly[(N-propionyl)iminoethylene] (1, M-n=4,280). Three samples of modified lipase (3) were prepared by changing the molar ratio of the N-succinimide activated ester of 1 (2) to lysyl groups ([2]/[Lys]). The enzymatic activities of 3 for ester hydrolysis in an aqueous solution and for esterification in benzene or chloroform were investigated. It was found that 3 was a more effective catalyst than unmodified and poly(ethylene glycol) modified lipase for both ester hydrolysis and esterification. Especially, in the case of 3a (average number of 2 per molecule of enzyme = 2.6), its ester hydrolysis activity (in a buffer at pH 7) and esterification activity (in benzene) were about three times and ten times higher than those of the original lipase, respectively. The effect of water in organic media on the enzymatic activity was also examined.