Immobilisation of horseradish peroxidase on Eupergit®C for the enzymatic elimination of phenol

Abstract

In this study, three different approaches for the covalent immobilisation of the horseradish peroxidase (HRP) onto epoxy-activated acrylic polymers (Eupergit®C) were explored for the first time, direct HRP binding to the polymers via their oxirane groups, HRP binding to the polymers via a spacer made from adipic dihydrazide, and HRP binding to hydrazido polymer surfaces through the enzyme carbohydrate moiety previously modified by periodate oxidation. The periodate-mediated covalent immobilisation of the HRP on hydrazido Eupergit®C was found to be the most effective method for the preparation of biocatalysts. In this case, amaximumvalue of the immobilised enzyme activity of 127 U/gsupport was found using an enzyme loading on the support of 35.2 mg/gsupport. The free and the immobilised HRP were used to study the elimination of phenol in two batch reactors. As expected, the activity of the immobilised enzyme was lower than the activity of the free enzyme. Around 85% of enzyme activity is lost during the immobilisation. However, the reaction using immobilised enzyme showed that it was possible to reach high degrees of phenol removal (around 50%) using about one hundredth of the enzyme used in the soluble form.