Immobilization of keratinase on chitosan grafted-β-cyclodextrin for the improvement of the enzyme properties and application of free keratinase in the textile industry

Abstract

Immobilization of enzymes is an effective and potential technique for improving the enzyme characteristics and plays an important role in reducing the final cost of enzymatic reactions. However, the method of enzyme immobilization should be easy, cost-effective and environment friendly when applicable at industrial scale. In present study, the successful biochemical characterization of free and immobilized keratinase was evaluated. The enzyme was effectively immobilized on chitosan and chitosan grafted-β-cyclodextrin beads. Enzyme yield of immobilized biocatalyst on chitosan alone and chitosan-β-CD-E was determined to be 90 and 93% respectively. Keratinase was able to act in highly alkaline conditions (optimum pH 11) both in free and immobilized form and showed maximum enzyme activity at 70 and 75 °C respectively. The free and immobilized enzyme exhibited remarkable thermo stability at 70 °C implying that it is capable for its usage in textile industry. The storage stability and reusability of the immobilized keratinase (chitosan-E and chitosan-β-CD-E) was significantly enhanced, with 25 and 53.5% activity, respectively, retained at 4 °C after 30 days of storage. In the preliminary experiments it was found that free keratinase have the potential to improve the quality of woollen fabrics and suitable for application in textile industries.