Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The elctrophoretic separation in polyacrylamide gel of laccase and peroxidase isoenzymes of the lignin-degrading fungus Pleurotus ostreatus was investigated. The optimal electrophoretic conditions were found: in the electrode buffer tris-diethyl barbituric acid pH 7.0 in the gradient gel-4-10% acrylamide. Seven peroxidase isoenzymes oxidizing base benzidine and guaiacol were identified and five laccase isoenzymes reacting with specific substrates-p-phenylene diamine, alphs-naphthol, pyrogallol, hydroquinone were determined.
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PMID:[Study of oxidative enzymes of the lignin-degrading fungus Pleurotus ostreatus]. 81 2

The fungi Pleurotus ostreatus and Trametes pubescens were grown in a mineral medium containing 1% of glucose and 0.9% of lignosulfonates introduced into the culture medium in the form of yeast waste liquor. Chromatography of extracts of the medium and determinations of sulphur and lignosulfonates have revealed that the fungi studied utilized the constituents of the yeast waste liquor (lignosulfonates) as carbon source. This was manifested in an increase of dry mass of the mycelium and protein as compared with the control. The constituents of the yeast waste liquor were also found to have a stimulating effect on the formation of both exo-and endoenzymes, laccase and peroxidase. This may indicate that these oxidases take part in the decomposition of lignosulfonates.
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PMID:Studies on the decomposition of lignosulfonates by the fungi Pleurotus ostreatus and Trametes pubescens. 117 50

Two filamentous fungi, the white-rot fungus Trametes versicolor and the soil fungus and potential biocontrol organism Trichoderma harzianum, have been grown in pure and mixed cultures on low-N (0.4 mM) and high-N (4 mM) defined synthetic media to determine the activities of selected wood-degrading enzymes such as cellobiase, cellulase, laccase, and peroxidases. Growth characteristics and enzyme activities were examined for potential correlations. Such correlations would allow the use of simple enzyme assays for measuring biomass development and would facilitate predictions about competitiveness of species in mixed fungal cultures. Our results show that while laccase and Poly Red-478 peroxidase activities indicate survival of the decay fungus, none of the monitored extracellular enzymes can serve as a quantitative indicator for biomass accumulation. As expected, the level of available nitrogen affected the production of the enzymes monitored: in low-N media, specific cellobiase, specific cellulase, and peroxidase activities were enhanced, while laccase activities were reduced. Most importantly, laccase activities of Trametes versicolor, and to a smaller extent, cellobiase activities of both fungi, were significantly induced in mixed cultures of Trametes versicolor and Trichoderma harzianum.
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PMID:Changes in selected enzyme activities during growth of pure and mixed cultures of the white-rot decay fungus Trametes versicolor and the potential biocontrol fungus Trichoderma harzianum. 161 57

Lignin peroxidase oxidizes non-phenolic substrates by one electron to give aryl-cation-radical intermediates, which react further to give a variety of products. The present study investigated the possibility that other peroxidative and oxidative enzymes known to catalyse one-electron oxidations may also oxidize non-phenolics to cation-radical intermediates and that this ability is related to the redox potential of the substrate. Lignin peroxidase from the fungus Phanerochaete chrysosporium, horseradish peroxidase (HRP) and laccase from the fungus Trametes versicolor were chosen for investigation with methoxybenzenes as a homologous series of substrates. The twelve methoxybenzene congeners have known half-wave potentials that differ by as much as approximately 1 V. Lignin peroxidase oxidized the ten with the lowest half-wave potentials, whereas HRP oxidized the four lowest and laccase oxidized only 1,2,4,5-tetramethoxybenzene, the lowest. E.s.r. spectroscopy showed that this congener is oxidized to its cation radical by all three enzymes. Oxidation in each case gave the same products: 2,5-dimethoxy-p-benzoquinone and 4,5-dimethoxy-o-benzoquinone, in a 4:1 ratio, plus 2 mol of methanol for each 1 mol of substrate. Using HRP-catalysed oxidation, we showed that the quinone oxygen atoms are derived from water. We conclude that the three enzymes affect their substrates similarly, and that whether an aromatic compound is a substrate depends in large part on its redox potential. Furthermore, oxidized lignin peroxidase is clearly a stronger oxidant than oxidized HRP or laccase. Determination of the enzyme kinetic parameters for the methoxybenzene oxidations demonstrated further differences among the enzymes.
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PMID:Comparison of lignin peroxidase, horseradish peroxidase and laccase in the oxidation of methoxybenzenes. 216 14

Acanthamoeba castellanii has a phenol oxidase activity that is believed to be a laccase. Enzyme activity was found in the outer cyst wall, in the cytoplasm of encysting amoebae and in the encystment medium. Encystment procedures were modified to promote an increase in the amount of soluble enzyme secreted during encystation. Acanthamoeba polyphenol oxidase has a pH optimum of 6.0 and a Km value of 0.21 mM with dihydroxyphenylalanine. The enzyme does not oxidize tyrosine, and it is inhibited by chloride but not by inhibitors of peroxidase. Its synthesis coincides with encystation, and known inhibitors of polyphenol oxidase prevent encystation. Polyphenol oxidase may have a role in making the cyst resistant to mechanical and chemical breakdown.
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PMID:Polyphenol oxidase produced during encystation of Acanthamoeba castellanii. 393 Jul 6

The ability to degrade oligo- and polysaccharides by enzymes of the glycosidase and glucan-glucan hydrolyse type, and esterase, phosphatase, proteinase, peroxidase, catalase, laccase and tyrosinase activities were tested in 35 strains of 11 sections of the genus Fusarium.
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PMID:Enzyme apparatus of the genus Fusarium. 624 4

The oxidative stability of rosmarinic acid (alpha-O-caffeoyl-3,4-dihydroxyphenyllactic acid) in lavandin (Lavandula x intermedia) cell cultures was studied in an attempt to explain the decrease in the rosmarinic acid content of aging cell cultures, a process which is associated with the appearance of brown pigments. The oxidation of rosmarinic acid by a partially purified protein fraction was followed spectrophotometrically and by HPLC. The results showed that rosmarinic acid oxidation was almost totally dependent on the presence of H2O2 and protein, and that brownish products were the results of this oxidation, resembling those shown by aging cell cultures. Since this protein fraction contains peroxidase activities and shows the total absence of tropolone-sensitive polyphenoloxidase (catecholase) and laccase activities, rosmarinic acid oxidation is tentatively proposed to be caused by a peroxidase-like activity. These results support the existence of a rosmarinic acid peroxidase in cell cultures of lavandin flowers, which may be involved in the oxidative destruction of rosmarinic acid, and which may also be responsible for the formation of brown pigments during aging, lowering the yields of rosmarinic acid.
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PMID:Tentative evidence of a rosmarinic acid peroxidase in cell cultures from lavandin (Lavandula x intermedia) flowers. 786 8

A bleachery effluent from a sulfite process pulp mill, which was extracted with alkali and treated with oxygen and hydrogen peroxide (EOP), was treated with two fungi, Trametes versicolor and Stagonospora gigaspora. Trametes versicolor did not cause any depolymerization or degradation of effluent lignins but increased the amount of chromophores, whereas S. gigaspora depolymerized the EOP lignins and caused a substantial reduction in aromatic compounds. For both fungal treatments, CuO oxidation caused a decrease in the yield of the aldehydes within the vanillyl and p-hydroxy phenol families, which was faster than the rates of decrease in the yields of the corresponding acids and ketones. However, only S. gigaspora caused changes in the pattern of the 11 characteristic lignin phenols produced by CuO oxidation, reflecting a preferential metabolism of some phenolic precursors. This fungus decreased the yield of total vanillyl phenols (V), which contributed the bulk of the 11 lignin oxidation products, from 93% initially to 59%. As a consequence, coumaryl (C), syringyl (S), and p-hydroxy phenols (P) became relatively enriched to 1.2, 6.5, and 33%, respectively. The stability of EOP-lignin constituent subunits is S > P > C > V. The two fungi differed significantly in their level of enzyme activities. In effluent-free medium, the ratio of laccase to peroxidase was higher for T. versicolor than for S. gigaspora. The presence of EOP-lignins significantly increased this ratio. No lignin peroxidase was detected but manganese peroxidase and laccase were detected during degradation activities.
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PMID:Degradability of chlorine-free bleachery effluent lignins by two fungi: effects on lignin subunit type and on polymer molecular weight. 801 7

This method was proposed earlier for measuring glucose in a peroxidase-glucose oxidase system but has not been studied for determination of manganese peroxidase (MnP) activity. The assay is based on the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone (MBTH) and 3-(dimethylamino)benzoic acid (DMAB). The reaction of MBTH and DMAB in the presence of H2O2, Mn2+, and MnP gives a deep purple-blue color with a broad absorption band with a peak at 590 nm. The extinction coefficient is high (53,000 M-1 cm-1), so low MnP activities can be detected. Lignin peroxidase and laccase, usually present in cultures of white rot fungi, gave little or no interference at the concentrations tested. However, slight interference from very high LiP activity may occur at very low MnP activity.
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PMID:Determination of manganese peroxidase activity with 3-methyl-2-benzothiazolinone hydrazone and 3-(dimethylamino)benzoic acid. 807 99

The ligninolytic enzymes produced by the white rot fungus Phanerochaete sordida in liquid culture were studied. Only manganese peroxidase (MnP) activity could be detected in the supernatant liquid of the cultures. Lignin peroxidase (LiP) and laccase activities were not detected under a variety of different culture conditions. The highest MnP activity levels were obtained in nitrogen-limited cultures grown under an oxygen atmosphere. The enzyme was induced by Mn(II). The initial pH of the culture medium did not significantly affect the MnP production. Three MnP isozymes were identified (MnPI, MnPII, and MnPIII) and purified to homogeneity by anion-exchange chromatography followed by hydrophobic chromatography. The isozymes are glycoproteins with approximately the same molecular mass (around 45 kDa) but have different pIs. The pIs are 5.3, 4.2, and 3.3 for MnPI, MnPII, and MnPIII, respectively. The three isozymes are active in the same range of pHs (pHs 3.0 to 6.0) and have optimal pHs between 4.5 and 5.0. Their amino-terminal sequences, although highly similar, were distinct, suggesting that each is the product of a separate gene.
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PMID:Manganese peroxidases of the white rot fungus Phanerochaete sordida. 813 19


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