Purification and Characterization of a Novel Peroxidase from Bitter Gourd (Momordica charantia)

Peroxidase from bitter gourd was purified by three step purification scheme; ammonium sulphate fractionation, gel filtration and affinity chromatography. The enzyme was purified 42 fold with the retention of 67% of the initial activity. The enzyme exhibited its maximum activity at pH 5.6 and 40 °C. The enzyme retained half of its activity even after 1 h incubation at 60 °C. Molecular weight of the purified glycosylated bitter gourd peroxidase determined by Sephacryl S- 100 and SDS-PAGE was 43 kDa. The stokes radius, diffusion coefficient and sedimentation coefficient of the purified peroxidase were 27.3 Å, 8.17 x 10-7 cm2/sec and 3.74 S, respectively. Km for o-dianisidine and ABTS were 1.3 and 4.9 mM, respectively. The activity of the enzyme was inhibited by sulfide, azide and L-cysteine. The carbohydrate content and sulfydryl groups of the enzyme were 25% (w/w) mass of the protein and 16 mmoles/mole of the protein, respectively.