Effect of the support alkyl chain nature in the functional properties of the immobilized lipases

Abstract

Supports coated with amino-hexyl and amino octyl have been prepared from glyoxyl agarose beads and compared in their performance with octyl-agarose to immobilize lipases A and B from Candida antarctica (CALA and CALB). Immobilization courses were similar using all supports, but enzyme release was more difficult using the amino-alkyl supports suggesting a mixed interfacial activation/ionic exchange immobilization. The enzyme activity and specificity (using p-nitrophenyl propionate, triacetin and both isomers of methyl mandelate) greatly depended on the support. In many instances the enzymes immobilized on the new supports offered higher activities and enantiospecificity in the hydrolysis of both enantiomers of methyl mandelate (mainly using CALB). This was coupled to a lower enzyme stability using the new supports, even in the presence of high ionic strength, suggesting that the amphipathic could be responsible of the enzyme lower stability. Using CALB, it was possible to detect a higher exposition of the enzyme Trp groups to the medium by florescence spectra after its immobilization on the amino-alkyl-supports, correlating to the higher activity and lower stability results.