A peroxidase from bitter gourd (Momordica charantia) with enhanced stability against organic solvent and detergent:: A comparison with horseradish peroxidase

A detailed comparative stability study of the purified bitter gourd peroxidase and commercially available pure horseradish peroxidase has been undertaken against various denaturants. Stability of the enzymes was monitored spectrophotometrically as well as by ellipticity changes in far-circular dichroism region. Bitter gourd peroxidase was more thermo-stable. The disruption of secondary structure and enzymatic activity at various temperatures was greater for horseradish peroxidase. Bitter gourd peroxidase retained remarkably greater fraction of catalytic activity as compared to horseradish peroxidase in the alkaline pH range. The difference in catalytic activity of bitter gourd peroxidase by varying the pH was related to the change in secondary structure as manifested by the change in CD value at 222 nm. It was further complemented by the far UV CD spectra, which showed greater retention of secondary structure at pH 6.0 and 10.0. BGP had remarkable stability in the presence of urea, sodium dodecyl sulphate and dimethyl formamide. In view of its higher stability, bitter gourd peroxidase can serve as a better alternative to horseradish peroxidase in clinical and environmental analyses as well as in various biotechnological applications. (c) 2007 Elsevier B.V. All rights reserved.