Study of kinetic characteritics of peroxidase enzyme from Cucurbita pepo

Peroxidase (EC 1.11.1.7) is in class of hemeprotein and has the principal oxidation function using hydrogen peroxide and various substrate. Peroxidases are widely used in medical diagnosis and in various laboratory experiments, therefore, today a lot of effort is made to new sources of plant tissue with the appropriate peroxidase activity. Cucurbita pepo (zucchini) is a summer squash that can grow to about one meter and has a green fruit, swelling ovary of the flower. In this work we have determined the factors affecting on measurement of enzyme activity and enzyme kinetics at 25 ° C and a wavelength of 470 nm. The results showed that the maximum enzyme activity at optimum temperature of 50 ° C and pH 6.5. The enzyme is stable in the range of pH 4 to 8. The Km and Vmax values of peroxidase from zucchini were measured for hydrogen peroxide in the presence of guaiacol, 6.25 and 0.1 mM/min respectively. The effect of the presence of various salts (including: Mg2, Cu2, K, Pb2, Ag, Fe2) in 1 mM concentration was measured in the reaction mixture. Our results showed the highest inhibitory effect of lead and iron ions by peroxidase activity measurements.