Purification and characterization of caprine kidney uricase, possessing novel kinetic and thermodynamic properties

Abstract

Purified uricase from a caprine kidney, possessed Km and Vmax values of 1.1 mg ml−1 and 3512 IU (mg protein)−1 for uric acid hydrolysis, respectively. The optimum temperature and pH for catalytic activity were 40 °C and 8.5, respectively. The activation energy for formation of ES complex was 13.6 kJ mol−1. Enthalpy (ΔH*), entropy of activation (ΔS*) and Gibbs free energy demand of uricase inactivation were 62.8 kJ mol−1, −102 J mol−1 K−1 and 104.3 kJ mol−1, respectively. Gibbs free enrgy demand for substrate binding and transition state stabilization were also determined which were comparable with those for themostable enzymes.