Stability profile of <i>Pistia stratiotes</i> leaf peroxidase

Abstract

Peroxidases are widely distributed in nature and are used in multiple industrial applications. Sources of peroxidases with notable stability are therefore being explored for commercial purposes. Pistia stratiotes leaf peroxidase was purified and characterized. It exhibited maximum activity at pH 6.0 after 10 minutes of incubation, which shifted to pH 6.5 after 60 minutes of incubation. Peroxidase from P. stratiotes leaf showed moderate stability after heating at 50ºC for 60 minutes and at 60ºC for 30 minutes. This enzyme was strongly inhibited by EDTA while urea had only a slight denaturing effect with approximately 65% of the activity retained after 60 minutes exposure. There was reduction in P. stratiotes leaf peroxidase activity in the presence of Pb 2+ (67%), Hg 2+ (70%), Ni 2+ (75%), Cu 2+ (12%), Co 2+ (60%), Ca 2+ (45%) and Mn 2+ (65%) at 6mM concentration. Acetone activated the enzyme in a concentration-dependent manner while the presence of methanol and ethanol in the reaction mixture led to 16% decrease in the activity of the enzyme at 20% concentration. Results obtained from this study revealed that P.stratiotes leaf peroxidase is moderately stable and thus has potential for some industrial applications.