Strategies of covalent immobilization of a recombinant Candida antarctica lipase B on pore-expanded SBA-15 and its application in the kinetic resolution of (R,S)-Phenylethyl acetate

Abstract

A recombinant Candida antarctica lipase B expressed in Pichia pastoris (LIPB) was immobilized on pore-expanded SBA-15 previously modified 3-amino-propyltriethoxysilane (APTES) and activated with two bifunctional reagents, glutaraldehyde (GA) or divinylsulfone (DVS), producing the biocatalysts: SBA-15-APTES-GA-LIPB and SBA-15-APTES-DVS-LIPB, respectively. After LIPB immobilization, both preparations were then modified with glutaraldehyde, producing the biocatalysts: SBA-15-APTES-GA-LIPB-GA, SBA-15-APTES-DVS-LIPB-DVS. Alternatively, LIPB was immobilized on SBA-15-APTES-DVS at pH 10.2 and the biocatalyst was named SBA-15-APTES-DVS-LIPB-pH10. The different biocatalysts were assayed to check the effect of the immobilization strategies on the stability and in the substrate specificity during the kinetic resolution of (R,S)-Phenylethyl acetate. The thermal stability of some new preparations were higher than LIPB adsorbed on SBA-15 (SBA-15-LIPB) and LIPB immobilized on Glyoxyl-agarose. High conversions in the enzymatic kinetic resolution were obtained (43–50%) for all biocatalysts studied. Regarding activity and stability, the SBA-15-APTES-DVS-LIPB-pH10 was the most successful strategy, since, in first cycle, the maximum conversion was obtained (50%), and the biocatalyst remained active and enantioselective even after five successive cycles.