Production and purification of Remazol brilliant blue R decolorizing peroxidase from the culture filtrate of Pleurotus ostreatus

An extracellular H2O2-requiring Remazol brilliant blue R (RBBR) decolorizing enzymatic activity was found in the culture medium of Pleurotus ostreatus. The enzymatic activity was maximally obtained in idiophase, and the optimum C/N ratio was 24. High C/N ratios repressed the enzymatic activity, and addition of veratryl alcohol had no effect on the production of enzyme, The enzyme was purified by ammonium sulfate fractionation, Sephacryl S-200 HR chromatography, DEAE Sepharose CL-6B chromatography, and Mono Q chromatography, The purification of RBBR decolorizing peroxidase, as judged by the final specific activity of 6.00 U/mg, was 54.5-fold, with a yield of 9.9%. The molecular mass of the native enzyme determined by gel permeation chromatography was found to be about 73 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the enzyme was a monomer with a molecular mass of 71 kDa. The enzyme was optimally active at pH 3.0 to 3.5 and al 25 degrees C. Under standard assay conditions, the apparent K-m values of the enzyme toward RBBR and H2O2 were 10.99 and 32.97 mu M, respectively, The enzyme had affinity toward various phenolic compounds and artificial dyes, and it was inhibited bg Na2S2O5, potassium cyanide, NaN3, and cysteine, The absorption spectrum of the enzyme exhibited maxima at 407, 510, and 640 nm. The addition of H2O2 to the enzyme resulted in an absorbance decrease at 407 and 510 nm.