Studies on the Thermal Stability of Peroxidase from Leaf of Oil Palm (Elaeis guineensis)

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.