Extraction and purification of a peroxidase from soil

A peroxidase was extracted from soil using 50 mM phosphate buffer, pH 6.0, and was purified by DEAE-cellulose chromatography and gel filtration (Sephadex G-75). A large number of substrates were tested to compare the substrate specificity of the soil peroxidase with that of horseradish peroxidase. Inhibition studies revealed that both soil peroxidase and horseradish peroxidase were competitively inhibited by glutathione and thiourea. Opitmal activity of the soil peroxidase was observed at pH 5.0. During ultrafiltration a significant amount of the enzyme was retained by membranes with a molecular weight cutoff of 30,000. The Sephadex purified enzyme was composed of 50% carbohydrate. 12% phosphorus, and 10% protein. It was heat labile and showed saturation kinetics.