Peroxidases are widely distributed in nature and are involved in multiple industrial applications owing to their critical physiological roles. Sources of peroxidases with notable stability are therefore being explored for commercial purposes. Pistia stratiotes leaf peroxidase was purified and characterized for its stability properties. Its optimum pH shifted from 6.0 to 6.5 after incubation for 1 hour while it showed moderate stability after heating at 50˚C for 60 minutes and at 60˚C for 30 minutes. P. stratiotes leaf peroxidase 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 Pb2+, Hg2+, Ni2+, Cu2+, Co2+, Ca2+ and Mn2+. Acetone activated the enzyme in a concentration-dependent manner while the presence of methanol and ethanol in the reaction mixture led to decrease in the activity of the enzyme. Results obtained from this study revealed that P. stratiotes leaf peroxidase is moderately stable and thus has potential for some industrial applications.
Key words: Pistia stratiotes, urea, enzyme activity, peroxidase, stability
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