Purification, characterization, and coal depolymerizing activity of lignin peroxidase from Gloeophyllum sepiarium MTCC-1170

Lignin peroxidase from the liquid culture filtrate of Gloeophyllum sepiarium MTCC-1170 has been purified to homogeneity. The molecular weight of the purified enzyme was 42 kDa as determined by SDS-PAGE. The K m values were 54 and 76 µM for veratryl alcohol and H₂O₂, respectively. The pH and temperature optima were 2.5 and 25°C, respectively. Depolymerization of coal by the fungal strain has been demonstrated using humic acid as a model of coal. Depolymerization of humic acid by the purified lignin peroxidase has been shown by the decrease in absorbance at 450 nm and increase in absorbance at 360 nm in presence of H₂O₂. Depolymerization of humic acid by the purified enzyme has also been demonstrated by the decrease in the viscosity with time of the reaction solution containing humic acid, H₂O₂, and the purified lignin peroxidase. The influence of NaCl and NaN₃ and inhibitory effects of various metal chelating agents on the lignin peroxidase activity were studied.