Abstract

The crucial roles of proteases in food and other industries stimulate research to find additional sources of the enzyme especially from non-conventional sources. In this study, protease was partially characterized from Jatropha curcas leaves.The enzyme had pH and temperature optima of 4.0 and 45^oC respectively. A decline in residual activity of the enzyme was observed at above 45^oC and the activation energy (Ea) from Arrhenius plot was 0.57kJ/mol. The enzyme showed specificity in the order; casein>hemoglobin> albumin> ovalbumin. Initial velocity studies for the determination of kinetic parameters revealed a K_M and V_max of 0.48 mg/ml and 0.014µmol/min respectively with a computed index of physiological efficiency (K_cat) of 0.029 min^-1. Furthermore, Dixon-Webb’s plot identified ionizable groups at the active site with pKa₁ and pKa₂ of 5.0 and 5.3 respectively as well as an enthalpy of ionization of 0.047 kcal/mol implicating aspartate as an important amino acid at the active site of the enzyme. The protease was highly sensitive to cysteine protease specific inhibitor iodoacetate while 1,10phenanthroline and ethylenediaminetetraacetate slightly inhibited the enzyme. Data from this study suggest that J. curcas protease possesses closely similar properties to other known industrial proteases.

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