Purification and enzymatic properties of a textile dye-decolourizing peroxidase from Moringa oleifera roots

Peroxidases are ubiquitous enzymes involved in the oxidation of a variety of aromatic substrates including textile dyes, which are harmful for aquatic life and human health. Hence, the present study describes the purification of a peroxidase, named Mo POX, from Moringa oleifera roots using DEAE-Sephacel and gel filtration chromatography on a Superdex® 75 column. The peptide sequences recorded by mass spectrometry analysis confirmed the identity of Mo POX with other plant peroxidases. The optimum pH and temperature of enzyme activity were 5.2 and 70 °C, respectively. Its enzymatic activity in the presence of metal ions and classical peroxidase inhibitors was also evaluated. Mo POX follows Michaelis-Menten kinetics, with specificity, in ascending order, to the substrates ABTS < eugenol < O -dianisidine ≅ guaiacol, besides being highly thermostable. The purified peroxidase (0.015, 0.030 or 0.150 mg/mL) degraded different dyes (50 or 100 mg/L), such as Remazol ® Blue RGB, Remazol ® Navy RGB and Telon ® Turquoise M-5G 85%. Decolorization rates varied from 15 to 90% depending on the dye concentration, enzyme concentration and exposure time. Mo POX is the first peroxidase purified from M. oleifera roots, and the results showed it has biotechnological potential for biodegradation of hazardous compounds.