Studies on the Thermal Stability of Peroxidase from Leaf of Oil Palm (<i>Elaeis guineensis</i>)

Abstract

Peroxidase was extracted from leaves of oil palm tree with 0.01M phosphate buffer pH 7.0. It was partially purified using 70% ammonium sulphate ((NH₄)₂SO₄) precipitation. This resulted in peroxidase with activity of (26U/ml) and specific activity of 35.8U/mg. Effect of heat on the activity of peroxidase was studied at temperature of 323-363°K. After gel filtration on sephadex G100, the peroxidase activity increased to 27U/ml, with specific activity of 55U/mg .The overall purification fold was 4 with 51.9% enzyme recovery. The peroxidase partially purified from leaves of oil palm tree showed pH and temperature optima of 5.0 and 50°C respectively. High pH and temperature stabilities of pH 5.0 to pH 9.0 and 50°C to 70°C were obtained respectively. Also, the activation energy (Ea) of the reaction was - 21.616kj/mol. The free energy changes (ΔG) were 96008.64, 96315.59, 97901.63, 94132.33 and 97146.75kj/mol at 323,333,343,353 and 363°K respectively. It was observed that the D-values were decreasing with increasing temperature with a Z-value of 0.044. The enthalpy results suggest that the reaction was exothermic, non-spontaneous and reversible.