The effect of substrate hydrophobicity on the kinetic behaviour of immobilized Candida rugosa lipase

Candida rugosa lipase (EC 3.1.1.3.) was immobilized in a hydrophilic polyurethane foam and used in the hydrolysis of olive oil, in n-hexane. The results obtained were compared with those from a previous study, in which the same lipase preparation was used in the esterification of ethanol with butyric acid. The initial rate of hydrolysis increased exponentially with increasing olive oil concentration. In contrast, for the esterification reaction, Michaelis-Menten kinetics with inhibition by both substrates, had been observed. The effect of medium viscosity, stirring conditions and size of immobilization particles could not explain the observed kinetics of the hydrolytic reaction. However, a direct relationship was observed between the log P values of the reaction medium and the initial rate of hydrolysis, i.e., activation of the immobilized Candida rugosa lipase appears to be promoted by a high hydrophobicity of the reaction medium. In the case of the esterification reaction, no similar correlation was found.