Specificity enhancement towards hydrophobic substrates by immobilization of lipases by interfacial activation on hydrophobic supports

Different immobilized preparations (using octyl-agarose or CNBr agarose) of lipases from Candida rugosa (CRL) and from Alcaligenes sp. (QL) were assayed in the hydrolysis of phthalic acid dibutyl ester and phenylmalonate diethyl ester. The activity of octyl-CRL against di n-butyl phthalate was much higher than that of the enzyme immobilized on BrCN-CRL, while the activity against phthalic acid mono-butyl ester was much lower. Using di n-ethyl phenylmalonate, CRL immobilized on CNBr-agarose exhibited a moderate preference for the diester versus the monoester. A similarly immobilized preparation of QL hydrolyzed in an even faster fashion the monoester than the diester. However, when both enzymes were adsorbed on octyl-agarose, the reaction stopped at the monoester. Moreover, the reaction using this immobilization strategy proceeds much faster than using the other immobilization strategy. Both results suggested that the immobilization of lipases via interfacial activation on hydrophobic supports may can increase the enzyme specificity towards hydrophobic substrates. The lipase QL immobilized on octyl-agarose achieved conversions higher than 99% of and (mono) n-ethyl phenylmalonate, with an ee value of 85% favoring the (+)-isomer.