Peroxidases belong to a large family of enzymes which contain a ferri-protoporphyrin IX prosthetic group and catalyze the oxidation of a wide variety of phenolic compounds such as guaiacol, pyrogallol, acid chlorogenic, catechin and catechol in the presence of hydrogen peroxide or organic hydroperoxides. Wide applications of peroxidase in different areas of clinical biochemistry, biotechnology and food industry enhances interests for further study on this enzyme. In this investigation, peroxidase were extracted and partially purified from Broccoli and the enzyme activity was determined. A crude extract from fresh broccoli's inflorescence was homogenized, centrifuged and precipitated by ammonium sulfate (90%) at 4ºC. The enzyme activity in the crude extract and dialysate was monitored in 414 nm with 0.8 mM H2O2 as substrate and 2 mM ABTS as electron donor in phosphate-citrate buffer with pH 4 (optimum pH) and at 50 oC (optimum temperature). Total activity and the specific activity of peroxidase were 1011 U and 0.27 U/mg in crude extract and 243 U and 1.11 U/mg in dialysate after ammonium sulfate precipitation. Our study suggested that the broccoli's inflorescence can be used as a source of peroxidase enzyme for studies on the activity and characterization of its kinetic parameters in food and pharmaceutical industries.
