Esterase activity of biocomposites constituted by lipases adsorbed on layered zirconium phosphate and phosphonates: selective adsorption of different enzyme isoforms

Aqueous solutions of crude extract of lipase from Candida rugosa (C-CRL) and of a semipurified material obtained by treating C-CRL with propan-2-ol (PT-CRL) were used as a source of biomaterial for its adsorption onto the surface of layered micro-crystals of α-zirconium phosphate Zr(HPO4)2 and phosphonates such as Zr(C6H5PO3)2, Zr(HPO4)(C6H5PO3) and Zr(HOOCCH2PO3)(HPO4), which possess groups with different hydrophobic character anchored to the inorganic matrix. Several biocomposites have been obtained by changing the temperature and the time of equilibration of the various supports with the C-CRL and PT-CRL solutions. The biocomposites have shown different esterase activities and enantio-selectivities in the hydrolysis of p-nitrophenylacetate (p-NPA), ethyl butyrate and (±)-methyl-2-(4-chlorophenoxy) propionate as a function of the nature of the support and of the time and temperature of equilibration. These results have been interpreted on the basis of a selective adsorption of different isoforms of the enzyme. The biocomposites can be stored for more than 1 month at 4 °C and can be used for several cycles without a significant decrease in catalytic activity.