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1.
Appl Biochem Biotechnol ; 166(3): 563-75, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22081331

ABSTRACT

A laccase has been purified from the liquid culture growth medium containing bagasse particles of Fomes durissimus. The method involved concentration of the culture filtrate by ultrafiltration and anion exchange chromatography on diethyl aminoethyl cellulose. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and native polyacrylamide gel electrophoresis both gave single protein band indicating that the enzyme preparation was pure. The molecular mass of the purified laccase determined from SDS-PAGE analysis was 75 kDa. Using 2,6-dimethoxyphenol as the substrate, the determined K (m) and k (cat) values of the laccase are 182 µM and 0.35 s(-1), respectively, giving a k (cat)/K (m) value of 1.92 × 10(3) M(-1) s(-1). The pH and temperature optimum were 4.0 and 35 °C, respectively. The purified laccase has yellow colour and does not show absorption band around 610 nm found in blue laccases. Moreover, it transformed methylbenzene to benzaldehyde in the absence of mediator molecules, property exhibited by yellow laccases.


Subject(s)
Benzaldehydes/chemistry , Cellulose/chemistry , Coriolaceae/enzymology , Fungal Proteins/chemistry , Laccase/chemistry , Toluene/chemistry , Chromatography, DEAE-Cellulose , Culture Media , Electrophoresis, Polyacrylamide Gel , Fungal Proteins/isolation & purification , Hydrogen-Ion Concentration , Kinetics , Laccase/isolation & purification , Molecular Weight , Pyrogallol/analogs & derivatives , Pyrogallol/chemistry , Substrate Specificity , Temperature , Ultrafiltration
2.
Enzyme Res ; 2011: 319105, 2011.
Article in English | MEDLINE | ID: mdl-21804936

ABSTRACT

Peroxidases have turned out to be potential biocatalyst for a variety of organic reactions. The research work reported in this communication was done with the objective of finding a convenient rich source of peroxidase which could be used as a biocatalyst for organic synthetic reactions. The studies made have shown that Luffa aegyptiaca (gourd) fruit juice contains peroxidase activity of the order of 180 enzyme unit/mL. The K(m) values of this peroxidase for the substrates guaiacol and hydrogen peroxide were 2.0 and 0.2 mM, respectively. The pH and temperature optima were 6.5 and 60°C, respectively. Like other peroxidases, it followed double displacement type mechanism. Sodium azide inhibited the enzyme competitively with K(i) value of 3.35 mM.

3.
Indian J Microbiol ; 50(Suppl 1): 132-8, 2010 Oct.
Article in English | MEDLINE | ID: mdl-22815586

ABSTRACT

Secretion and enzymatic characteristics of lignin peroxidases from Gloeophyllum sepiarium MTCC 1170, Cladosporium herbarum MTCC 346, Lenzites betulina MTCC 1183, Daedalea flavida MTCC 145, Hexagonia teruis MTCC 1119 and Coirolopsis floccosa MTCC 1177 ligninolytic fungal strains have been reported. Secretion of lignin peroxidase by these ligninolytic fungal strains have been found to be in the range of 0.86 to 3.0 enzyme unit per ml of the culture medium. The enzymatic characteristics like K(m), pH and temperature optima of all the lignin peroxidases of the above fungal strains have been determined using veratryl alcohol and H(2)O(2) as the variable substrates. The K(m) values using veratryl alcohol as the substrate were found to be 65.0 µM, 58.5 µM, 63.0 µM, 54.5 µM, 54.6 µM and 61.0 µM respectively. The K(m) values using H(2)O(2) as the substrate were found to be 88.0 µM, 86.0 µM, 71.0 µM, 67.0 µM, 80.0 µM and 78.0 µM respectively. The pH optima values for lignin peroxidases of the above ligninolytic fungal strains were found to be 2.5, 2.4, 2.4, 2.25, 2.5 and 2.8 respectively, where as the temperature optima values were 25°C, 24°C, 25°C, 23°C, 24°C and 25°C respectively.

4.
Appl Biochem Biotechnol ; 157(2): 311-20, 2009 May.
Article in English | MEDLINE | ID: mdl-18607547

ABSTRACT

The culture conditions for maximum secretion of laccase by Loweporus lividus MTCC-1178 have been optimized. The laccase from the culture filtrate of L. lividus MTCC-1178 has been purified to homogeneity. The molecular weight of the purified laccase is 64.8 kDa. The enzymatic characteristics like K(m), pH, and temperature optimum using 2,6-dimethoxyphenol have been determined and found to be 480 microM, 5.0, and 60 degrees C, respectively. The K(m) values for other substrates like catechol, m-cresol, pyrogallol, and syringaldazine have also been determined and found to be 230, 210, 320, and 350 microM, respectively.


Subject(s)
Laccase/isolation & purification , Laccase/metabolism , Polyporaceae/enzymology , Culture Media , Electrophoresis, Polyacrylamide Gel , Enzyme Stability , Hydrogen-Ion Concentration , Molecular Weight , Pyrogallol/analogs & derivatives , Pyrogallol/metabolism , Substrate Specificity , Temperature
5.
Indian J Biochem Biophys ; 45(5): 345-9, 2008 Oct.
Article in English | MEDLINE | ID: mdl-19069847

ABSTRACT

Five indigenous Aspergillus flavus strains MTCC-2206, 1884, 1883, 1783 and 2456 were screened for the secretion of quercetinase. Fungal strains MTCC-2206, 1884, 1883, and 1783 were found to secrete the quercetinase in the range of 0.24-0.36 enzyme unit/mL of the culture medium, while MTCC-2456 secreted only 0.04 enzyme unit/mL. The enzymatic characteristics of quercetinase were determined. The Km values using quercetin as the substrate were 12.5 microM, 14.0 microM, 12.5 microM and 13.0 microM for the quercetinase produced by MTCC-2206, 1884, 1883 and 1783, respectively. The pH optima for the above enzymes were 6.5, 6.5, 6.0 and 6.0 and temperature optima were 45, 40, 45 and 50 degrees C, respectively. The partial purification from only one strain MTCC-2206 was achieved (nearly 3-fold purification).


Subject(s)
Aspergillus flavus/enzymology , Dioxygenases/metabolism , Dioxygenases/chemistry , Electrophoresis, Polyacrylamide Gel , Hydrogen-Ion Concentration , Kinetics , Molecular Weight
6.
Sheng Wu Gong Cheng Xue Bao ; 24(12): 2068-73, 2008 Dec.
Article in English | MEDLINE | ID: mdl-19306577

ABSTRACT

The effect of lignin containing natural substrates corn-cob, coir-dust, saw-dust, wheat straw and bagasse particles on the extracellular secretion of laccase in the liquid culture growth medium of Pleurotus sajor-caju MTCC 141 has been studied. The culture conditions for maximum secretion of laccase by Pleurotus sajor-caju MTCC 141 have been optimized. Homogeneous preparation of laccase from the culture filtrate of the fungus has been achieved using ammonium sulphate precipitation, anion exchange chromatography on DEAE and gel filtration chromatography on Sephadex G-100. The purified enzyme preparation gave a single protein band in SDS-PAGE analysis indicating a molecular weight of 90 kD. The enzymatic characteristics Km, k(cat), pH and temperature optima of the purified laccase have been determined using 2, 6-dimethoxyphenol as the substrate and have been found to be 35 micromol/L, 0.30 min(-1), 4.5 and 37 degrees C respectively. The Km values for the other substrate like catechol, m-cresol, pyrogallol and syringaldazine have also been determined which were found to be 216 micromol/L, 380 micromol/L, 370 micromol/L and 260 micromol/L respectively.


Subject(s)
Laccase/isolation & purification , Laccase/metabolism , Pleurotus/enzymology , Culture Media , Extracellular Space/enzymology , Pleurotus/growth & development , Pyrogallol/analogs & derivatives , Pyrogallol/pharmacology
7.
Indian J Biochem Biophys ; 43(4): 239-43, 2006 Aug.
Article in English | MEDLINE | ID: mdl-17133768

ABSTRACT

Solanum melongena fruit juice contains peroxidase activity of the order of 0.125 IU/mL. A method for the 11-fold purification of the enzyme was developed. The Km values of the peroxidase for the substrates guaiacol and hydrogen peroxide were 6.5 mM and 0.33 mM, respectively. The pH and temperature optima were 5.5 and 84 degrees C, respectively using guaiacol as the substrate. Sodium azide and phenyl hydrazine inhibited the enzyme competitively.


Subject(s)
Peroxidases/chemistry , Solanum melongena/enzymology , Beverages , Dose-Response Relationship, Drug , Fruit , Guaiacol/pharmacology , Hydrogen Peroxide/pharmacology , Hydrogen-Ion Concentration , Kinetics , Phenylhydrazines/pharmacology , Sodium Azide/pharmacology , Temperature
8.
Indian J Exp Biol ; 40(7): 802-6, 2002 Jul.
Article in English | MEDLINE | ID: mdl-12597550

ABSTRACT

Secretion of ligninperoxidase [E.C.1.11.1.7] by Penicillium citrinum, Fusarium oxysporum and Aspergillus terreus in liquid culture growth medium has been demonstrated. Enzymatic characteristics like Km, pH and temperature optima using veratryl alcohol as the organic substrate of ligninperoxidases from above sources have been determined. Km values using veratryl alcohol as substrate for enzymes from P. citrinum, F. oxysporum and A. terreus were 69, 64 and 60 microM respectively. Km values using H2O2 as the variable substrate were 64, 72 and 80 microM. The pH optima were 4.0, 2.3 and 2.0 respectively. The values of temperature optima were 30 degrees, 25 degrees and 22 degrees C for the enzymes from P. citrinum, F. oxysporum and A. terreus respectively.


Subject(s)
Aspergillus/enzymology , Fusarium/enzymology , Penicillium/enzymology , Peroxidases/metabolism , Hydrogen-Ion Concentration , Kinetics , Substrate Specificity , Temperature
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