Purification of catalase enzyme from Thymus nummularius and examination of the effects of varying glucose concentrations on catalase activity

Catalase (EC 1.11.1.6), an antioxidant enzyme, breaks down reactive oxygen species, hydrogen peroxide (H2O2), into water and oxygen. In this study, the partial purification of catalase was obtained from Thymus nummularius M. Bieb. through ammonium sulfate (NH4)2SO4 precipitation, dialysis, and desalting/buffer exchange by using a PD-10 Sephadex G-25 M column. The isolated enzyme had a specific activity of 1294.45 U/mg protein and a purification fold of 7.80. The SDS-PAGE analysis indicated a molecular weight ranging between 37 and 50 kDa. The optimal pH and temperature for catalase activity were determined to be pH 8.0 and 25 °C, respectively. The kinetic parameters, maximum velocity (Vmax) 277.78 U/mL and Michaelis constant (KM) 34.17 mM were estimated from Lineweaver-Burk plots. Furthermore, catalase activity was evaluated at glucose concentrations ranging between 25 and 500 ppm. Enzyme activity increased at 25–100 ppm, significantly decreased at 250 ppm, and then increased again at 500 ppm. These results suggest that glucose may modulate catalase activity in a concentration-dependent manner. Even though the exact regulatory mechanism remains unclear, this effect could have potential implications for glucose-sensitive metabolic systems.