Calcium alginate-starch hybrid support for both surface immobilization and entrapment of bitter gourd (Momordica charantia) peroxidase

Calcium alginate-starch hybrid gel was employed as an enzyme carrier both for surface immobilization and entrapment of bitter gourd peroxidase. Entrapped crosslinked concanavalin A-bitter gourd peroxidase retained 52% of the initial activity while surface immobilized and glutaraldehyde crosslinked enzyme showed 63% activity. A comparative stability of both forms of immobilized bitter gourd peroxidase was investigated against pH, temperature and chaotropic agent; like urea, heavy metals, water-miscible organic solvents, detergent and inhibitors. Entrapped peroxidase was significantly more stable as compared to surface immobilized form of enzyme. The pH and temperature-optima for both immobilized preparations were the same as for soluble bitter gourd peroxidase. Entrapped crosslinked concanavalin A-bitter gourd peroxidase showed 75% of the initial activity while the surface immobilized and crosslinked bitter gourd peroxidase retained 69% of the original activity after its seventh repeated use. (C) 2008 Elsevier B.V. All rights reserved.