Peroxidase from soybean seeds was extracted and partially purified by ammonium sulfate precipitation technique and then by ion-exchange OEAE-cellulose chromatography. It was observed that conditions at which enzyme exhibited maximum activity did not change even after ammonium sulfate precipitation, while after OEAE-cellulose chromatography. specific activity of enzyme was increased. Various kinetic parameters were applied for peroxidase activity determination. The enzyme under discussion was found to be quite active up to noe with optimum temperature of 2~oC Optimum pH for the enzyme was 5.5. Thermal treatment of crude extract of soybean peroxidase was more stable at pH 3.0. It was found that enzyme followed the Michealis-Menton mechanism and 5.238 absorbance units/min and 2mM were the calculated values for Vmax and Km. The enzyme became reactivated when placed at _10°C for 4 hr after partial inactivation at 70°C for 3 min. It was found that the crude and partially purified extract possessed all appreciable enzyme activity. Soybean appears to be a rich and cheaper source of peroxidases from among potato. tomato and cauliflower. Key words: kinetics, peroxidase, soybean
