Poly (Ethylene-Alt-Maleic Anhydride) Ionic Modification of Lipase B from Candida antarctica Immobilized on Octyl Agarose Beads Alters Its Catalytic Properties

Abstract

The lipase B from Candida antarctica was immobilized on octyl-agarose using low and high (one that saturated the support surface with enzyme) loadings. Then, both biocatalysts were aminated, and the aminated and non-aminated biocatalysts were used in further experiments. The enzyme activity was determined using substrates with different structures. The modification of the four biocatalysts with poly (ethylene-alt-maleic anhydride) revealed that only a marginal covalent reaction occurs. That way, the ion exchange of the polymer on the immobilized enzyme surface should be responsible for the enzyme functional changes. The modification of the biocatalysts with this polymer produced mixed results for enzyme activity (depending on the enzyme loading, use of aminated or non-aminated enzyme, polymer concentration and used substrate), in some instances more than doubling the activity, in others reducing it by 5–6 times the activity when compared to the unmodified biocatalyst. The effects on biocatalyst stability were also mixed, depending on the same factors; in some instances, great stabilization could be found (e.g., in inactivation of the highly loaded aminated biocatalyst at pH 7.0, the unmodified biocatalyst kept 5% of the initial activity, while the biocatalyst modified with 1% of the polymer maintained 80%), but in other instances, enzyme stability was reduced after modification. It was shown that one of the effects of the polymer modification was the prevention of the enzyme release during inactivation.