Catalytic, Kinetic and Thermodynamic Characteristics of an Extracellular Lipase from Penicillium notatum

Lipase of Penicillium notatum was purified to electrophoretic homogeneity by ammonium sulphate precipitation, ion-exchange, and hydrophobic interaction chromatography. The purified enzyme displayed a solitary band in the 46-kDa region on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS–PAGE). The pH and temperature optima were found to be 9.5 and 40 °C, respectively. It showed stability over broad pH range (pH 6.0–12) and higher thermal tolerance with half-lives ( t 1/2 ) of 8.25, 3.2, 1.12, and 0.58 h at 40, 50, 60 and 70 °C, respectively. The K m and V max values for p -nitro phenyl palmitate ( p NPP) hydrolysis were 3.33 mM and 232.6 µmol/mL min −1 , respectively. The energy of activation for denaturation E a(d) was 81.1 kJ/mol, whereas the entropy (ΔS * ), enthalpy (ΔH * ) and free energy (ΔG * ) of thermal inactivation of lipase were recorded to be −0.083 Jmol −l K −l , 78.48 and 104.54 kJ/mol, respectively, at 40 °C. The enzymatic activity was substantially improved by Ca 2+ and Mg 2+ , and suppressed in the presence of Co 2+ , Cd 2+ , Pb 2+ and Fe 3+ ions to various levels. Exposure to hydrophobic environment did not affect the enzyme stability; however, protease solution deactivated the enzyme. Considering all these properties, this fungal lipase would be an interesting candidate for future organic synthesis application. Graphical Abstract