Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.2 (laccase)
 4,656 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Wheat straw cultures of the brown rot fungi Gloeophyllum striatum and G. trabeum degraded 2,4-dichlorophenol and pentachorophenol. Up to 54% and 27% 14CO2, respectively, were liberated from uniformly 14C-labeled substrates within 6 weeks. Under identical conditions Trametes versicolor, a typical white rot species employed as reference, evolved up to 42% and 43% 14CO2 and expressed high activities of laccase, manganese peroxidase, and manganese-independent peroxidase. No such activity could be detected in straw or liquid cultures of Gloeophyllum. Moreover, G. striatum degraded both chlorophenols most efficiently under non-cometabolic conditions, i.e. on a defined mineral medium lacking sources of carbon, nitrogen and phosphate.
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PMID:Degradation of 2,4-dichlorophenol and pentachlorophenol by two brown rot fungi. 1036 17

A new label--laccase from the fungus Coriolus hirsutus--was applied for solid-phase enzyme-linked immunosorbent assays of the pesticide 2,4-dichlorophenoxyacetic acid (2,4-D). Two proposed assays are based on (1) competitive binding of antibody-laccase conjugate with immobilized 2,4-D-protein conjugate and 2,4-D in tested sample, and (2) competition of 2,4-D and 2,4-D-laccase conjugate for binding with immobilized antibodies. Kinetic and concentration dependencies for these reactions were studied, and the ELISAs were optimized in accordance with the data obtained. The elaborated systems permit the detection of 2,4-D in concentrations down to 10-20 ng/mL; time of the assays is 1.5-2 h. The main advantage of the laccase label, in comparison with the widely used peroxidase one, lies in the lack of hydrogen peroxide from substrate mixture, because dissolved oxygen plays the role of oxidizer.
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PMID:Laccase from Coriolus hirsutus as alternate label for enzyme immunoassay. Determination of pesticide 2,4-dichlorophenoxyacetic acid. 1039 Aug 10

Production of ligninolytic enzymes and degradation of 14C-ring labeled synthetic lignin by the white-rot fungus Cyathus stercoreus ATCC 36910 were determined under a variety of conditions. The highest mineralization rate for 14C dehydrogenative polymerizates (DHP; 38% 14CO2 after 30 days) occurred with 1 mM ammonium tartrate as nitrogen source and 1% glucose as additional carbon source, but levels of extracellular laccase and manganese peroxidase (MnP) were low. In contrast, 10 mM ammonium tartrate with 1% glucose gave low mineralization rates (10% 14CO2 after 30 days) but higher levels of laccase and manganese peroxidase. Lignin peroxidase was not produced by C. stercoreus under any of the studied conditions. Mn(II) at 11 ppm gave a higher rate of 14C DHP mineralization than 0.3 or 40 ppm, but the highest manganese peroxidase level was obtained with Mn(II) at 40 ppm. Cultivation in aerated static flasks gave rise to higher levels of both laccase and manganese peroxidase compared to the levels in shake cultures. 3,4-Dimethoxycinnamic acid at 500 microM concentration was the most effective inducer of laccase of those tested. The purified laccase was a monomeric glycoprotein having an apparent molecular mass of 70 kDa, as determined by calibrated gel filtration chromatography. The pH optimum and isoelectric point of the purified laccase were 4.8 and 3.5, respectively. The N-terminal amino acid sequence of C. stercoreus laccase showed close homology to the N-terminal sequences determined from other basidiomycete laccases. Information on C. stercoreus, whose habitat and physiological requirements for lignin degradation differ from many other white-rot fungi, expands the possibilities for industrial application of biological systems for lignin degradation and removal in biopulping and biobleaching processes.
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PMID:Production of ligninolytic enzymes and synthetic lignin mineralization by the bird's nest fungus Cyathus stercoreus. 1057 Aug 16

Ganoderma lucidum, a white rot basidiomycete widely distributed worldwide, was studied for the production of the lignin-modifying enzymes laccase, manganese-dependent peroxidase (MnP), and lignin peroxidase (LiP). Laccase levels observed in high-nitrogen (HN; 24 mM N) shaken cultures were much greater than those seen in low-nitrogen (2.4 mM N), malt extract, or wood-grown cultures and those reported for most other white rot fungi to date. Laccase production was readily seen in cultures grown with pine or poplar (100-mesh-size ground wood) as the sole carbon and energy source. Cultures containing both pine and poplar showed 5- to 10-fold-higher levels of laccase than cultures containing pine or poplar alone. Since syringyl units are structural components important in poplar lignin and other hardwoods but much less so in pine lignin and other softwoods, pine cultures were supplemented with syringic acid, and this resulted in laccase levels comparable to those seen in pine-plus-poplar cultures. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of concentrated extracellular culture fluid from HN cultures showed two laccase activity bands (M(r) of 40,000 and 66, 000), whereas isoelectric focusing revealed five major laccase activity bands with estimated pIs of 3.0, 4.25, 4.5, 4.8, and 5.1. Low levels of MnP activity ( approximately 100 U/liter) were detected in poplar-grown cultures but not in cultures grown with pine, with pine plus syringic acid, or in HN medium. No LiP activity was seen in any of the media tested; however, probing the genomic DNA with the LiP cDNA (CLG4) from the white rot fungus Phanerochaete chrysosporium showed distinct hybridization bands suggesting the presence of lip-like sequences in G. lucidum.
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PMID:Lignin-modifying enzymes of the white rot basidiomycete Ganoderma lucidum. 1058 81

In the present study we investigated the possibility of proteinases, intracellular and extracellular, being involved in the regulation of ligninolytic activities in cultures of Trametes versicolor during the shift from primary growth (i.e. trophophase) to idiophase triggered by nitrogen or carbon starvation. These studies were performed using specific inhibitors added to the cultures of T. versicolor. Addition of PMSF (irreversible inhibitor of serine proteinases) or chloroquine (the lysosomotropic agent inhibiting intralysosomal degradation of proteins) revealed distinct differences in the activity of ligninolytic enzymes between nutrient-deprived and non-starved cultures. The addition of PMSF during the transfer of mycelia to the nutrient limited media significantly enhanced the activities of laccase (2-7-fold) and of unspecified peroxidases (2-4-fold). The activity of lignin peroxidase decreased with PMSF, both in tropho- and in idiophasic cultures. The enhanced activities of laccase and general peroxidases (horseradish peroxidase-like, HRP-like) were accompanied by markedly altered patterns of both intracellular and extracellular proteolytic activities revealed by electrophoretic analysis with polyacrylamide gels containing the copolymerized substrate (haemoglobin or gelatin, respectively). The experiments with chloroquine added to nutrient-deprived cultures showed that inhibition of vacuolar proteolysis resulted in lowered activities of laccase and peroxidase. Electrophoretic analysis revealed altered patterns of intracellular proteinases upon chloroquine addition to nutrient-starved cultures. Moreover, chloroquine was found to enhance the activity of proteases secreted in carbon-starved cultures. From the results it is concluded that both intracellular (including vacuolar) and extracellular proteases are involved in the regulation of laccase and peroxidase activity in cultures of T. versicolor under nutrient limitation.
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PMID:Studies on the role of proteases in the white-rot fungus Trametes versicolor: effect of PMSF and chloroquine on ligninolytic enzymes activity. 1074 99

The effects of various factors on the biosynthesis of extracellular laccase (EC 1.14.18.1) by the basidiomycete Coriolus hirsutus (Wulf.: Fr.) Quel. no. 072 during submerged cultivation were examined. Optimal parameters for cultivation in a fermenter of 10 l were determined: temperature, 28 degrees C; stirrer rotation speed, 160 rpm; and the inoculum volume, 15% of the working volume of the fermenter. The filtrate contained peroxidase, laccase, and phenol oxidase activities and displayed a high thermal stability.
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PMID:[Optimization of conditions for cultivation of the basidiomycete Coriolus hirsutus--producer of extracellular laccase]. 1075 81

Chlorinated phenols and anilines were transformed by oxidoreductive catalysts with release of chloride ions in both the absence and the presence of humic substances (syringaldehyde, catechol, and humic acid). Dehalogenation of these xenobiotics resulted from oxidative coupling reactions occurring at the chlorinated sites of the substrates. The effect of humic substances on dehalogenation depended on the mechanism of oxidative coupling. In a free-radical reaction mediated by peroxidase, laccase, or birnessite (delta-MnO2), syringaldehyde enhanced the dehalogenation of most of the chlorinated phenols, but it did not enhance the dehalogenation of the chloroanilines. With catechol, which does not form free radicals, dehalogenation was reduced or remained the same for both the chlorophenols and the chloroanilines. However, in tyrosinase-mediated reactions controlled by nucleophilic addition, catechol enhanced the dehalogenation of most of the chlorophenols, whereas syringaldehyde had little effect. Humic acid in most cases enhanced the dehalogenation of the chlorophenols, but it had little effect on the dehalogenation of the chloroanilines. On a molar basis, changes in dehalogenation caused by humic substances were proportional to the respective changes in substrate transformation. Only syringaldehyde was capable of releasing disproportionately high amounts of chloride ions from chlorophenols, apparently as a result of multiple crosscouplings to one molecule of the substrate.
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PMID:Dehalogenation of xenobiotics as a consequence of binding to humic materials. 1078 90

The influence of aromatic compounds and Mn ions on activities of ligninolityc enzymes from white-rot fungus Pleurotus floridae has been studied. The specific inducers: vanillic acid and vanillyl alcohol--for activity of manganese-dependent peroxidase; vanillyl alcohol--for activity of cellobiose: quinone oxidoreductase during submerged, fermentation of Pleurotus floridae in Kirk's medium have been revealed. The inducers of laccase activity among studied aromatic compounds have not been revealed. The influence of Mn2+ in concentration range 0.4-68.4 mM on activities of ligninolytic enzymes of submerged culture of fungus P. floridae has been studied. Concentration of Mn ions 32.4 mM was optimal for manganese-dependent peroxidase activity.
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PMID:[Effect of aromatic compounds and Mn2+ on the ligninolytic enzyme complex from the fungus Pleurotus floridae (FRIES) Kummer--a white-rot wood fungus]. 1079 Oct 56

Steady-state and single-turnover kinetics for the oxidation of the N-substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4-10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k(cat)/K(m)) varied from 1 x10(7)M(-1)s(-1) to 2.6 x 108 M(-1)s(-1) at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pKa values of 4.9-5.7 and 7.7-9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8x 10(5) M(-1) s(-1) to 2.0 x 10(7) M(-1) s(-1) at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6 x 10(8)M(-1)s(-1) and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0 x 10(7) M(-1) s(-1) and 0.29 eV.
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PMID:Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines. 1090 44

The amounts of intra- and extracellular guaiacol peroxidase, ascorbic peroxidase, glutathione peroxidase, superoxide dismutase, laccase, and catalase present in Botrytis cinerea, cultured in three different media: Kovac synthetic medium, Sabouraud fluid medium, and a medium containing malt extract, were determined. The activity of two enzymes, ascorbic peroxidase and glutathione peroxidase, has not been previously described in B. cinerea. The detected amount of the enzymes showed considerable variability in the three different culture media. The presence of an array of enzymes capable of metabolizing hydrogen peroxide, whose levels are determined by the conditions under which the fungus grows, shows that B. cinerea is well equipped to contend with the occurrence of host-produced active oxygen species.
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PMID:Enzymes of Botrytis cinerea capable of breaking down hydrogen peroxide. 1098 1


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