Meera Yadav

Purification and characterization of lignin peroxidase from Loweporus lividus MTCC-1178

Lignin peroxidase from the culture filtrate of Loweporus lividus MTCC‐1178 has been purified to homogeneity using Amicon concentration and DEAE cellulose chromatography. The molecular weight of the purified lignin peroxidase using SDS‐PAGE analysis has been found to be 40 kDa. The Km values for veratryl alcohol and H2O2 for the purified enzyme were 58 and 83 μM, respectively. The calculated kcat value of the purified enzyme using veratryl alcohol as the substrate was 2.5 s−1. The pH and temperature optima of lignin peroxidase have been found to be 2.6 and 24°C, respectively.

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 Km 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.

Oxidation of polyaromatic hydrocarbons in systems containing water miscible organic solvents by the lignin peroxidase of Gleophyllum striatum MTCC‐1117

Lignin peroxidase has been purified to homogeneity using a process of concentration by ultrafiltration and anion exchange chromatography on diethylaminoethyl (DEAE) cellulose from the liquid culture filtrate of the brown rot fungi Gleophyllum striatum MTCC‐1117. The molecular mass of the purified enzyme is 43 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) analysis. The K m values for the enzyme using veratryl alcohol, hydrogen peroxide and n‐propanol were 66 µM, 82 µM and 476 µM, respectively. The pH and temperature optima of the enzyme were 2.8 and 25°C, respectively. The enzyme is completely inhibited by 20% of the water miscible organic solvents acetone dioxane, diethylether, acetonitrile and dimethylformamide. The lignin peroxidase oxidizes polycyclic aromatic hydrocarbons pyrene, acenaphthene, anthracene, dibenothiophene and 9‐methyl anthracene.

Purification and characterization of lignin peroxidase from Pleurotus sajor caju MTCC-141.

Abstract The culture conditions for extracellular secretion of lignin peroxidase by Pleurotus sajor caju MTCC–141 in the liquid culture growth medium amended with lignin containing natural substrates have been studied. Secretion of lignin peroxidase has been found to be maximum in the presence of bagasse. Lignin peroxidase from the liquid culture filtrate has been purified to homogeneity. Two isozymes having relative molecular masses 38 and 40 kDa have been isolated. The enzymatic characteristics like Km, pH, and temperature optima of the major isozyme (40 KDa) has been determined using veratryl alcohol, n-propanol, and H2O2 as the substrate. The Km values for veratryl alcohol, n-propanol, and H2O2 have been found to be 57 μ M, 500 μ M, and 80 μ M, respectively. The pH and temperature optima of lignin peroxidase have been found to be 3 and 30°C, respectively. The inhibition of the enzyme activity by sodium azide has been studied and it has been found to be uncompetitive, with KI value of 4 mM.

Purification and characterisation of lignin peroxidase from Pycnoporus sanguineus MTCC-137

Extracellular secretion of lignin peroxidase from Pycnoporus sanguineus MTCC-137 in the liquid culture growth medium amended with lignin containing natural sources has been shown. The maximum secretion of lignin peroxidase has been found in the presence of saw dust. The enzyme has been purified to homogeneity from the culture filtrate of the fungus using ultrafiltration and anion exchange chromatography on DEAE-cellulose. The purified lignin peroxidase gave a single protein band in sodium dodecylsulphate polyacrylamide gel electrophoresis corresponding to the molecular mass 40 kDa. The Km, kcat and kcat/Km values of the enzyme using veratryl alcohol and H2O2 as the substrate were 61 M, 2.13 s−1, 3.5 × 104 M−1s−1 and 71 M, 2.13 s−1, 3.0 × 104 M−1 s−1 respectively at the optimum pH of 2.5. The temperature optimum of the enzyme was 25°C.

Purification, characterisation and coal depolymerisation activity of lignin peroxidase from Lenzitus betulina MTCC-1183

Lignin peroxidase from the culture filtrate of Lenzitus betulina MTCC-1183 has been purified to homogeneity using concentration by ultrafiltration and anion exchange chromatography on DEAE cellulose. The molecular weight of the purified lignin peroxidase using SDS-PAGE analysis was 43 kDa. Specific activity of the enzyme was 29.58 IU/mg. The Km values for veratryl alcohol and H2O2 for the purified enzyme were 54 and 81 μM, respectively. The kcat value of the purified enzyme was 2.3 s−1 using 3,4-dimethoxybenzyl alcohol as the substrate. The optimal conditions for the lignin peroxidase assay were detected at pH 2.4 and 22°C. Thermal stability of the purified enzyme has also been studied and its activation energy for deactivation was 287 kJ/mol. The purified lignin peroxidase depolymerised humic acid in presence of H2O2. Depolymerisation of coal by the L. betulina MTCC-1183 has been demonstrated using humic acid as a model of coal.

Ligninolytic Enzymes for Water Depollution, Coal Breakdown, and Paper Industry

Lignin breakdown modifies lignocellulose structure to produce smaller carbohydrates usable for further bioconversion. White rot fungi produces ligninolytic enzymes such as lignin peroxidase, manganese peroxidase, laccases and versatile peroxidase, which efficiently mineralize lignin. We review applications of ligninolytic enzymes. Applications include delignification of lignocellulose, removal of organic pollutants, wastewater treatment, dye decolorization, soil treatment, breakdown of coal into low molecular weight fractions, biopulping and biobleaching in paper industries, and enzymatic polymerization in polymer industries.

Coal Depolymerising Activity and Haloperoxidase Activity of Mn Peroxidase from Fomes durissimus MTCC-1173

Mn peroxidase has been purified to homogeneity from the culture filtrate of a new fungal strain Fomes durissimus MTCC-1173 using concentration by ultrafiltration and anion exchange chromatography on diethylaminoethyl (DEAE) cellulose. The molecular mass of the purified enzyme has been found to be 42.0 kDa using SDS-PAGE analysis. The K m values using MnSO4 and H2O2 as the variable substrates in 50 mM lactic acid-sodium lactate buffer pH 4.5 at 30°C were 59 μM and 32 μM, respectively. The catalytic rate constants using MnSO4 and H2O2 were 22.4 s−1 and 14.0 s−1, respectively, giving the values of k cat/K m 0.38 μM−1s−1 and 0.44 μM−1s−1, respectively. The pH and temperature optima of the Mn peroxidase were 4 and 26°C, respectively. The purified MnP depolymerises humic acid in presence of H2O2. The purified Mn peroxidase exhibits haloperoxidase activity at low pH.