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)

Lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase activities in selected sub-tropical white rot fungal species from Zimbabwe were determined. The enzyme activities were assayed at varying concentrations of C, N and Mn2+. Manganese peroxidase and laccase activities were the only expressed activities in the fungi under the culture conditions tested. Trametes species, T. cingulata, T. elegans and T. pocas produced the highest manganese peroxidase activities in a medium containing high carbon and low nitrogen conditions. High nitrogen conditions favoured high manganese peroxidase activity in DSPM95, L. velutinus and Irpex spp. High manganese peroxidase activity was notable for T. versicolor when both carbon and nitrogen in the medium were present at high levels. Laccase production by the isolates was highest under conditions of high nitrogen and those conditions with both nitrogen and carbon at high concentration. Mn2+ concentrations between 11-25 ppm gave the highest manganese peroxidase activity compared to a concentration of 40 ppm or when there was no Mn2+ added. Laccase activity was less influenced by Mn2+ levels. While some laccase activity was produced in the absence of Mn2+, the enzyme levels were higher when Mn2+ was added to the culture medium.
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PMID:Ligninolytic enzyme production in selected sub-tropical white rot fungi under different culture conditions. 1144 59

The toxicity of thirteen isomers of mono-, di-, tri- and pentachlorophenols was tested in potato-dextrose agar cultures of the white rot fungi Panus tigrinus and Coriolus versicolor. 2,4,6-Trichlorophenol (2,4,6-TCP) was chosen for further study of its toxicity and transformation in liquid cultures of these fungi. Two schemes of 2,4,6-TCP addition were tested to minimize its toxic effect to fungal cultures: stepwise addition from the moment of inoculation and single addition after five days of growth. In both cases the ligninolytic enzyme systems of both fungi were found to be responsible for 2,4,6-TCP transformation. 2,6-Dichloro-1,4-hydroquinol and 2,6-dichloro-1,4-benzoquinone were found as products of primary oxidation of 2,4,6-TCP by intact fungal cultures and purified ligninolytic enzymes, Mn-peroxidases and laccases of both fungi. However, primary attack of 2,4,6-TCP in P. tigrinus culture was conducted mainly by Mn-peroxidase, while in C. versicolor it was catalyzed predominantly by laccase, suggesting a different mode of regulation of these enzymes in the two fungi.
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PMID:Transformation of 2,4,6-trichlorophenol by the white rot fungi Panus tigrinus and Coriolus versicolor. 1148 63

Degradation of yard wastes by Coprinus truncorum growing in a vertical aereated bioreactor or in flasks was studied. There was a constant decay of reducing sugars in the medium that avoided their accumulation and their possible repression of degradative enzymes. Endoxylanase activity at first showed a similar pattern in both culture conditions, with maximal activity on the 12th day, but flasks maintained a high activity thereafter. Flasks also showed a higher endoglucanase activity with a peak on the 18th day, whereas the maximal value in the bioreactor was reached on the 26th day. No Mn-peroxidase and only low values of laccase activity were found. The measurements of pH and soluble proteins during the incubation period were suitable indicators of the degradation process by C. truncorum.
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PMID:[Degradation of plant waste by Coprinus truncorum using 2 culture methods]. 1149 57

The relationship between production of 3-indoleacetic acid (IAA) and peroxidase and laccase activity was investigated in white-rot fungus Funalia trogii (Trametes trogii). F. trogii produced IAA and peroxidase and laccase as both primary metabolite and secondary metabolite; the levels of IAA may be influenced by peroxidase and laccase. A correlation exists between the levels of IAA and peroxidase-laccase activity.
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PMID:Relationship between production of 3-indoleacetic acid and peroxidase-laccase activities depending on the culture periods in Funalia trogii (Trametes trogii). 1150 98

The aromatic polymer lignin can be modified through promotion of oxidative coupling between phenolic groups on lignin and various phenols. The reaction is initiated by an oxidation of both components, e.g., by using the oxidoreductases laccase or peroxidase. Coupling between phenolic monomers and lignin has previously been studied by the use of radio-labeled phenols. In this study, incorporation of water-soluble phenols into kraft lignin, using laccase as catalyst, was investigated. Several phenols with carboxylic or sulfonic acid groups were used as markers for the incorporation. The modified lignin was isolated and the amount of phenol incorporated was characterized by means of titration, quantitative 1H-NMR, and quantitative 31P-NMR after modification with 2-chloro-4,4,5,5-tetramethyl-1,2,3-dioxaphospholane. Only a few of the phenols studied were found to be incorporated into lignin. When the phenol guaiacol sulfonate was incorporated into kraft lignin, the lignin became water-soluble at pH 2.4 and a low ionic strength due to the introduction of sulfonic acid groups. The content of sulfonic acid groups in the product was 0.5-0.6 mmol/g lignin. A lower amount of 4-hydroxyphenylacetic acid was incorporated under similar conditions.
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PMID:Enzymatic modification of kraft lignin through oxidative coupling with water-soluble phenols. 1152 17

Oxidative coupling of nitroaromatic compounds involving soil organic matter was examined as a means of soil remediation. Humic monomers, serving as model compounds for soil humic substances, were used as cosubstrates, applying phenoloxidases (laccase from Trametes villosa and peroxidase from horseradish) as oxidative biocatalysts. Without the addition of a cosubstrate, only 30% of 4-amino-2,6-dinitrotoluene (4ADNT) and no 2,4,6-trinitrotoluene (TNT) were transformed in the presence of the laccase. Adding various phenolic monomers produced differing effects on the enzyme-mediated transformation, which indicated that xenobiotics are preferentially bound to quinoid and phenolic moieties of soil humic substances. In the presence of the humic monomer catechol and the enzyme, up to 100% of 4ADNT and up to 80% of TNT were transformed. Enzymatic transformation of 4ADNT in the presence of catechol reached a maximum at pH 6.8. TNT transformation, however, further increased at pH values above 6.8, even in the absence of the enzyme, due to chemical polymerization of catechol. We postulate a two-step reaction mechanism. The humic monomer is initially oxidized to a semi-quinone radical by a phenoloxidase. Subsequent oxidative coupling involves reactions with additional humic monomers or anilinic products derived from TNT, forming an anilinoquinone via nucleophilic addition or a benzoquinone-imine through condensation.
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PMID:Interaction of 2,4,6-trinitrotoluene (TNT) and 4-amino-2,6-dinitrotoluene with humic monomers in the presence of oxidative enzymes. 1170 61

p-Coumaric acid (1) is an abundant phenolic natural product that exhibits both chemoprotectant and antioxidant properties. Microbial transformation screening studies showed that 1 was converted to 4-vinylphenol (4), 4-hydroxybenzoic acid (2), caffeic acid (5), protocatechuic acid (6), and other unidentified metabolites over 144 h. 4-Vinylphenol (4) and its dimer, (2R,2S)-4-(2,3-dihydro-5-hyroxy-2-benzofuranyl) phenol (11), were produced by Bacillus megaterium, and 5-[(E)-2-carboxyethenyl]-2,3-dihydro-2-(4-hydroxyphenyl)-3-benzofurancarboxylic acid (15) and 4-hydroxybenzoic acid (2) were produced by Curvularia lunata. On the basis of deuterium-labeling experiments, B. megaterium catalyzes the nonoxidative enzymatic tautomerization of 1 to a vinylogous beta-keto acid intermediate that decarboxylates to 4. The presence of peroxidase and laccase activities in C. lunata extracts suggests that these enzymes may be involved in one-electron, p-coumaric acid dimerization in this organism.
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PMID:Microbial transformations of p-coumaric acid by Bacillus megaterium and Curvularia lunata. 1172 May 22

The present study reports the results of a morpho-functional analysis of spleen pigmented cells from Rana esculenta L. and comparison with liver melanin-synthesizing cells, belonging to the macrophage cell lineage. Cytological and cytochemical analyses show that parenchymal pigmented cells of the spleen, like those of the liver, are positive to peroxidase and lipase reactions and have phagocytic properties. The observation of premelanosomes in various stages of differentiation, together with the demonstration of dopa oxidase activity in the melanosome proteins, indicate that spleen pigmented macrophages have endogenous melanogenic ability as do liver pigmented macrophages. Attempts to demonstrate tyrosinehydroxylase activity in melanosome protein extracts from frog spleen and liver, using the same protocol as for mammalian tyrosinases, gave negative results. As regards the dopa oxidase activity revealed, some of its properties differ from the typical behaviour observed for tyrosinases from different sources. Peroxidase activity is shown in spleen and liver melanosome proteins with p-phenylenediamine-pyrocatechol (PPD-PC), and not with typical peroxidase substrates. Suitable inhibition tests revealed that dopa oxidase and peroxidase activities might be supported by two different proteins. Liver melanosome extracts display a very strong laccase (dimethoxyphenoloxidase) activity but spleen extracts do not. Differences observed in the enzymatic properties of the spleen and liver melanosomes suggest that pigmented macrophages may undergo tissue-specific differentiation. These preliminary data show that the melanin pathway of pigmented macrophages is different from that of melanocytes and may pave the way to identification of a new melanogenic pathway in vertebrates.
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PMID:Spleen and liver pigmented macrophages of Rana esculenta L. A new melanogenic system? 1183 54

Polyvinyl alcohol (PVA) solutions (BP05 and BF17; 5.0%, wt v(-1)) were degraded by a combination of chemical (Fenton's reagent) and fungal (Phanerochaete chrysosporium) treatments. The overall degradations of BP05 and BF17 were 74.4 and 72.8%, respectively, as determined by chemical oxygen demand (COD) analysis, and 63.7% and 57.7%, respectively, as determined by total organic carbon (TOC) analysis. Increased retention times and changes in the intensity of the PVA peaks on gel permeation chromatograms indicated that PVA molecules of greater molecular weights were degraded to lower molecular weights by both the chemical and fungal treatments. The predominant enzyme secreted by P. chrysosporium in medium containing 2% (wt v(-1)) ground cereal bran in 60 mM phosphate buffer (pH 6.0) was manganese peroxidase. Neither laccase nor lignin peroxidase activity was detected. Manganese peroxidase was probably involved in the biodegradation of the PVA solutions.
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PMID:Biodegradation of polyvinyl alcohol by Phanerochaete chrysosporium after pretreatment with Fenton's reagent. 1184 67

The production of laccase by a Brazilian strain of Pleurotus pulmonarius was studied in solid state fermentation using wheat bran as substrate. Among oxidative and hydrolytic enzymes tested (laccase, aryl alcohol oxidase, lignin peroxidase, Mn peroxidase, xylanase and cellulase), laccase was the main enzyme produced by P. pulmonarius. The most suitable condition for maximum production of laccase (8,600 U/g substrate) was initial moisture content of 75% and 5 days of cultivation at 30 degrees C. The optimum pH and temperature for laccase activity were found to be 6.5 and 50 degrees C, respectively. P. pulmonarius laccase was stable at 50 degrees C for more than 6 hours, and it retained about 73% and 18% of its activity when heated for 1 h at 55 and 60 degrees C, respectively. The enzyme was greatly stable at alkaline pH, but not at acidic pH. The laccase activity appear to be correlated with the ability of crude extract to decolourize several industrial dyes.
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PMID:Production of laccase as the sole phenoloxidase by a Brazilian strain of Pleurotus pulmonarius in solid state fermentation. 1198 72


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