Modulation of lipase properties in macro-aqueous systems by controlled enzyme immobilization:enantioselective hydrolysis of a chiral ester by immobilized Pseudomonas lipase

摘要

Lipase from Pseudomonas fluorescens (PFL) has been immobilized by using different immobilization protocols.The catalytic behavior of the different PFL derivatives i nthe hydrolytic resolution of fully soluble(R,S) 2-hydroxy 4-phenyl butanoic acid ethyl ester (HPBE) in aqueous medium was analyzed.The soluble enzyme showed a significant but low enantioselectivity,hydrolyzing the S isomer more rapidly than the R-isomer (E=7).The enzyme,immobilized via a limited attachment to a long and flexible spacer arm,showed almost identical activity and specificity to the soluble enzyme.However,other derivatives,e.g.PFL adsorbed on supports covered by hydrophobic moieties (octyl,decaoctyl),exhibited significant hyperactivation on immobilization (approximately 7-fold).Simultaneously,the enantioselectivity of the PFL-immobilized enzyme was significantly improved (from E=7 to E=80).By using such derivatives,almost pure R ester isomer (e.e.>99%) has been obtained after 55% hydrolysis of the racemic mixture of a solution of 10% (w/v) (R.S)HPBE.The derivatives could be used for 10 cycles without any significant decrease in the activity of the biocatalyst.