Decolorization of Synthetic Dye Using Partially Purified Peroxidase from Green Cabbage (Brassica Oleracea)

Abstract

Peroxidase was extracted from cabbage and was purified in three different purification processes. It was first purified by ammonium sulphate precipitation and highest peroxidase activity was observed at 80% saturation. Hence, 80% saturation was used to mass produce the enzyme. The enzyme was again purified by dialysis which tends to remove salt as impurity from the precipitated enzyme. The enzyme was further purified by gel filtration which further removed salts and other proteins as impurities. The resulting enzyme was characterized to determine the optimum pH and temperature. The optimum pH and temperature were respectively 5.0 and 45oC. The Km and Vmax obtained from Lineweaver-Burk plot of initial velocities at different concentration of H2O2 were found to be 3.68mM and 37.04U/ml respectively. Also, Km and Vmax of o-dianisidine were found to be 9.89mM and 28.57U/ml respectively. The enzymatic activity of this cabbage peroxidase with hydrogen peroxide on synthetic dyes was investigated and was found to be very effective in the treatment and decolorization of these dyes. This partially purified enzyme could decolorize many synthetic dyes; Azo Brilliant Black, Azo Trypan Blue, Azo Blue 5, Azo Citrus Red 2, Azo Yellow 6, Azo Pink, Azo Purple, Vat Green 11 and Vat Orange 9. Azo Trypan Blue and Vat Orange 11 had the highest and least percentage decolorization of 88.62 and 12% respectively after contact time of 1 hour. The cabbage peroxidase was found to decolorize Azo dyes more and had little effect on Vat dyes. This peroxidase could be an important source for dye and waste water decolorization.