Investigating on the Stability of Peroxidase Extracted from Soybean (Glycine max var. Williams) and Effects of Na+ and K+ Ions on its Activity

In the present study, some techniques were used for Soybean peroxidase (SBP) purification including: ammonium sulfate fractionation, DEAE Sephadex anion exchange chromatography and Concanavalin A Sepharose 4B affinity chromatography. Molecular weight of purified SBP was estimated about 44 kDa by SDS-PAGE as a single polypeptide band. The optimal pH and temperature for enzyme activity were found to be 4. 5 and 70◦C, respectively. The enzyme was more stable in alkaline pH than acidic ones and could tolerate 10 minutes heating in 40-50◦C without any loss of its activity. Both NaCl and KCl were found to have significant effects on the enzyme stability, but presence of NaCl was more effective than KCl. Our results showed that after 24 hours incubation of the enzyme in the presence of 20 mM NaCl, more than 60٪ of the enzyme activity was remained while it would fall to 3٪ if incubation was not accompanied by NaCl. Purified peroxidase from seed hull of soybean relative to the other identified peroxidases was more stable, for this reason a lot of benefit will be considered by use of this enzyme in different industry.