Relevance of Substrates and Products on the Desorption of Lipases Physically Adsorbed on Hydrophobic Supports

Lipase B from Candida antarctica (CALB) has been physically immobilized on octyl-agarose via interfacial activation. The incubation of the enzyme in 80% ethanol at pH 5 and 25°C has not significant effect on enzyme activity. Moreover, the hydrolysis of 100mM tributyrin catalyzed by this biocatalyst exhibited a quite linear reaction course. However, a new cycle of tributyrin hydrolysis showed a drastic drop in the activity. SDS-PAGE gels of the supernatant and the biocatalyst showed a significant enzyme desorption after the reaction. Similar results could be appreciated using triacetin or sunflower oil, while using 300mM methyl phenyl acetate, butyl butyrate or ethyl butyrate most enzyme molecules remained immobilized. The results show that the detergent properties of some reaction products increase the enzyme release from the hydrophobic support, and this problem increased if the concentration of the reactants increased. Using 500mM tributyrin, even in fully aqueous medium, some enzyme desorption from the support may be observed. Thus, the results show a limitation of this kind of biocatalysts that should be considered in the selection of an industrial lipase biocatalyst.