Characterization of Pectin Methylesterase from Aspergillus niger

Abstract

The present study was undertaken to evaluate the characteristics of pectin methylesterase produced from Aspergillus niger. The enzyme had a molecular weight of 59.668 kDa. The enzyme exhibited maximum activity at 45°C. The enzyme lost most of its initial activity after 20 min of incubation at 75°C. Optimal activity and stability of the enzyme occurred at pH 4, with more than 90 % of retained activity after 10 min at pH 5. Michaelis constant (Km) was found equal to (1) mg/ml, whereas, maximum velocity (Vmax) was (1000) μmol/min. The catalyzed reaction by pectin methylesterase had activation energy equal to 9.66 Kcal/mol. The enzyme lost 24% and 13% of its initial activity during two months of storage at4°C and -20 °C, respectively. The enzyme was activated by NaCl, KCl and CaCl2 at concentration of 25 mM and inhibited by MgSO4, polygalacturonic acid, methanol, IAA and EDTA.