Peroxidase Activity in Extracts of Watermelon Pulp: Effects of Ethylenediaminetetraacetic Acid and Some Cations

Aim: The aim of this study was to evaluate the effects of EDTA and some chloride salts of Ca, Cr, Fe and Mg on the initial velocity (Vo) of crude peroxidase from the pulp of watermelon. Study Design: The study design is In vitro enzyme assay. Place and Duration of Study: This study was conducted in the Department of Biochemistry, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Edo State, Nigeria between in November 2023. Methodology: The crude peroxidase from the pulp of watermelon was prepared from 10 g of the pulp of watermelon using standard procedures. The initial reaction rate of the enzyme was determined by spectrophotomertically by monitoring the rate of formation of tetraguaiacol, the oxidation product of guaiacol at 470 nm in the absence and presence of varying concentrations of EDTA and the chloride salts of Ca, Cr, Fe and Mg. The total volume of the reaction mixture was 3 mL. The time course for the reaction was determined and the initial velocity calculated. Results: Results showed that EDTA reduced the activity of the enzyme. This reduction in activity was EDTA-concentration dependent. This suggest the inhibitory effects of EDTA on peroxidase from watermelon pulp. The chlorides salts of Ca, Cr, Fe and Mg were found to be activators of the peroxidase from the pulp of watermelon. This information could be beneficial in industrial application processes where peroxidase from pulp of watermelon is deployed for use. Conclusion: From this study, it could be inferred that EDTA has the potentials of reducing the activity of peroxidase from pulp of watermelon fruit while the chloride salts of Ca, Cr, Fe and Mg are potentially good activators. This information is very crucial as ongoing research to understand the mechanism of action of peroxidase from the pulp of watermelon fruit continues. Considering the industrial applications of peroxidase, this information contributes to knowledge of how this peroxidase works.