Influence of the support surface properties on the protein loading and activity of lipase/mesoporous carbon biocatalysts

Abstract

Three mesoporous carbons were selected as supports for two lipases from Candida antarctica (CALA and CALB). A commercially available mesoporous carbon (MB) was used as starting material. Two additional supports were prepared from MB by heat treatment at 1773 K and oxygen plasma, bringing about materials with marked differences in both textural and surface chemical properties. Heterogenisation of lipases was performed at different immobilisation pH (4–8 range). The lipase/mesoporous carbons showed an enhancement of the catalytic activity in the kinetic resolution of (±)-1-phenylethanol when compared to that of the unsupported enzymes. For CALA, enzyme loadings were controlled by enzyme–support electrostatic interactions, whereas adsorption of CALB was ruled by specific interactions related to the enzyme and support surface chemistry. No direct correlation was found between the protein loads and catalytic activity. The catalytic activity of CALA/carbon systems was found to depend on both immobilisation pH and selected support more strongly than CALB biocatalysts. Changes observed in the support textural properties affect less to protein adsorption and catalytic activity. Operational stability tests were carried out with selected biocatalysts, with no significant activity loss being observed after 10 consecutive cycles of use and recovery.