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)

A Curvularia sp. isolated from soil was found to contain laccase activity toward guaiacol as substrate. The organism produced an extracellular laccase in a medium containing yeast extract, peptone and dextrose. Initial medium pH 4.0 and cultivation temperature 30 degrees C were found to be most suitable for maximum enzyme production. The optimum pH and temperature for laccase activity were found to be 5.2 and 50 degrees C, respectively. Under optimum conditions, the enzyme had a Km (guaiacol) of 0.75 mmol/L and a V of 1.50 CU min-1 ml-1. Some divalent metal ions inhibited laccase activity at very low concentrations.
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PMID:Production of laccase by Curvularia sp. 182 35

A member of the laccase multigene family in Pleurotus ostreatus has been cloned and sequenced. The gene structure has been determined by comparison with the corresponding cDNA, synthesized by reverse transcription/PCR amplification. The gene encode a laccase isoenzyme of 533 amino acids which has already been purified and characterized [Palmieri, G., Giardina, P., Marzullo, L., Desiderio, B., Nitti, G., Cannio, R. & Sannia, G.(1993) Appl. Microbiol. Biotechnol. 39, 632-636]. More than 92% of the protein sequence, including the N and C termini, has been verified by fast-atom-bombardment mass spectrometry, thus confirming the correspondence between the gene and its protein product. The protein was N-glycosylated Asn444. Glycan analysis showed the presence of only a high-mannose structure containing varying numbers of mannose residues. The presence of O-linked oligosaccharides as well as other post-translational modification could be ruled out by the mass analysis.
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PMID:The gene, protein and glycan structures of laccase from Pleurotus ostreatus. 865 95

An isolate of Coriolus hirsutus constitutively expresses substantial amounts of extracellular laccase on a defined growth medium. The most efficient inducer of extracellular laccase synthesis was syringaldazine, which increased the enzyme yield by 1000% at a concentration of 0.11 microM. The constitutive form of the enzyme was purified 312-fold. Laccase from C. hirsutus, with an estimated molecular mass of 55 kDa and pI of 4.0, is a monomeric glycoprotein containing 12% carbohydrate consisting of mannose and N-acetylglucosamine. The laccase was found to contain 3.9-4.1 copper atoms per molecule. The absorption spectrum shows a maximum at 610 nm and a shoulder at 330 nm, which is typical of laccase possessing type 1 and type 3 copper atoms. The parameters of the first type of copper were determined by EPR as g perpendicular=2.046 and g parallel=2.200, A parallel=8.103 x 10(-3) cm-1. Laccase was found to be a pH-stable and thermostable enzyme. With organic substrates it exhibits a pH optimum of 4.5, but with the inorganic substrate K4[Fe(CN)6] this decreased to 3.5. The highest efficiency of catalysis was observed with sinapinic acid as the substrate. The kinetic constants kcat and Km of this reaction were 578 s-1 and 24 microM respectively. It was established that the kinetics of the assayed reaction shows a Ping Pong mechanism.
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PMID:Purification and characterization of the constitutive form of laccase from the basidiomycete Coriolus hirsutus and effect of inducers on laccase synthesis. 969 88

Germlings of Botrytis cinerea, an important fungal pathogen of plants, produce an extracellular matrix (ECM), or ensheathing film, that serves, in part, in their attachment (R. P. Doss, et al., Appl. Environ. Microbiol. 61:260-265, 1995). The composition of this film has been ascertained by using samples obtained by growing germlings on a glass surface, removing the fungal mycelium by vigorous washing, and collecting the tightly attached film by scraping the substratum with a razor blade. Slightly over half of the dry weight of the ECM was found to be carbohydrates (about 20%), proteins (about 28%), and lipids (about 6%). Hydrolysis of the carbohydrate portion of the ECM revealed that glucose was the most prominent monosaccharide present, comprising about 60% of the total monosaccharides. Also present were mannose (about 35%) and myo-inositol (about 5%). The proteinaceous fraction of the ECM was made up of a number of polypeptides separable by polyacrylamide gel electrophoresis. The lipid fraction of the ECM, analyzed by thin-layer chromatography, was made up of several simple lipid components, including free fatty acid, mono- and triacylglycerol, wax ester, fatty alcohol, and several unidentified components. No complex lipids were detected. Isolated ECM exhibited polygalacturonase and laccase activity and was able to catalyze the hydrolysis of p-nitrophenyl butyrate, a model substrate for assessing cutinase activity. Cellulase, pectin lyase, and pectin methyl esterase activities were noted with both heated and unheated ECM preparations. Proteinase activity was not detected.
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PMID:Composition and enzymatic activity of the extracellular matrix secreted by germlings of botrytis cinerea. 992 60

Pleurotus florida (ITCC 3308) produces two laccase enzymes (L1 and L2) in potato-dextrose media containing 0.5% yeast extract. Concentrated culture filtrate was separated on DEAE-Sephadex (A-50) column into two enzyme peaks, subsequently named L1 and L2. The L1 enzyme has been purified to homogeneity by ion-exchange and gel-permeation chromatography. L1 is a monomeric glycoprotein with a molar mass of 77 and 82 kDa as determined by SDS-PAGE and gel-filtration chromatography, respectively. The pI value of L1 has been determined to be 4.1. The optimum reaction temperature of the enzyme is 50 degrees C. The Km and some other kinetic parameters of L1 have been determined. Cyanide and azide completely inhibit the enzyme activity. The enzyme was fully active in 1:1 (V/V) buffer-chloroform for at least 2 h. Spectroscopic analysis revealed that the enzyme has four copper atoms, a type 1 copper, a type 2 copper and a type 3 binuclear copper.
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PMID:Purification and characterization of laccase-1 from Pleurotus florida. 1134 72

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

Antisense repression was used as a method to alter gene function in the human-pathogenic fungus Cryptococcus neoformans. The calcineurin A gene (CNA1) and the laccase gene (LAC1) were targeted since disruption of these loci results in phenotypes that are easy to screen (temperature sensitivity and lack of melanin, respectively). Serotype D yeasts were transformed with a plasmid containing the CNA1 cDNA in an antisense orientation under the control of the inducible GAL7 promoter, and serotype A yeasts were transformed with a plasmid containing the LAC1 cDNA in an antisense orientation under the control of the constitutive actin promoter. The calcineurin transformants demonstrated a temperature-sensitive phenotype only when grown on galactose, and the laccase transformants had decreased melanin production. Northern blot analysis of the calcineurin antisense transformants confirmed that the inducible phenotype was associated with a decrease in the native CNA1 transcript levels. Furthermore, it was possible to modestly impair growth of C. neoformans at 37 degrees C by using a 30 bp antisense oligonucleotide targeting CNA1. Antisense repression is now available as a tool for molecular studies in this organism, and may be applicable to other human-pathogenic fungi that have less amenable genetic systems.
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PMID:Antisense repression in Cryptococcus neoformans as a laboratory tool and potential antifungal strategy. 1178 13

The production conditions of extracellular laccase from Armilliria mellea and the characteristics of the enzyme were studied. The experiment proved that initial pH5.5 of the culture medium and temperature at 25 degrees C were favorable for laccase synthesis. As carbon resources, cellobiose and raffinose were better in terms of productivity than maltose, sorbose and galactose. Organic nitrogen source was more suitable for Armilliria mellea to synthesize laccase than inorganic nitrogen source. Peat extract (PE) enhanced notably the yield of laccase; the maximal yield was 7 times as much as that of the control when PE concentration was 50%. Three isozymes were detected in culture supernatant named A, B and C respectively after their mobility on PAGE. After concentrated by (NH4)2SO4 precipitation, laccase A was further purified to homogeneity by preparative native PAGE and anion exchange column chromatography. The native enzyme was a single polypeptide with a molecular mass of approximately 59 kD estimated by SDS-PAGE, while 58 kD by gel filtration chromatography under non-denaturing conditions. Determined by IEF its isoelectric point was 4.0. The optimal pH value and temperature were 5.6 and 60 degrees C respectively in catalytic reaction of oxidizing guaiacol. At 60 degrees C and 65 degrees C, half-lives of laccase A were 45 min and 36.8 min, respectively. Enzyme activity was inhibited with 100 mmol/L Cl-, but was activated with 1 mmol/L SO4(2-). However, if the concentration of NaN3 was only 1 mmol/L, laccase A lost its activity completely. 10 mmol/L EDTA had no effect on laccase A, while 1 mmol/L Cu2+ could enhance its activity. Laccase A showed a good stability when the pH of the buffer varied from 5.2 to 7.2. Using guaiacol as the substrate, the Km was 1.026 mmol/L and the Vmax was 5 mumol/(min.mg); using ABTS instead, the Km was 0.22 mmol/L and Vmax was 69 mumol/(min.mg).
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PMID:[Studies on production, purification and partial characteristics of the extracellular laccase from Armilliria mellea]. 1238 43

A new enzyme has been isolated from leaves of the weed Tellima grandiflora (fringe cups, Saxifragaceae) that catalyzed the O(2)-dependent oxidation of 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose to tellimagrandin II, the first intermediate in the (4)C(1)-glucose derived series of ellagitannins. CD-spectra revealed that the 4,6-O-HHDP-residue of the in vitro product had the (S)-stereoconfiguration characteristic of tellimagrandin II from natural sources. The enzyme, for which a M(r) of ca. 60,000 was determined, was purified to apparent homogeneity. It had a pH-optimum at pH 5.0, an isoelectric point at pH 6.3 and was most stable at pH 4.2. Inhibition studies suggested that this new enzyme, for which the systematic name 'pentagalloylglucose: O(2) oxidoreductase' is proposed, belongs to the vast group of laccase-type phenol oxidases (EC 1.10.3.2).
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PMID:Oxidation of pentagalloylglucose to the ellagitannin, tellimagrandin II, by a phenol oxidase from Tellima grandiflora leaves. 1262 Mar 41

The influence of carbohydrates: glucose, fructose, galactose, galacturonic acid, xylose, lactose, sucrose, pectin and inulin, were evaluated as sole carbon source for the production of laccases by the ascomycete, Botryosphaeria sp. Veratryl alcohol, a laccase inducer, was added to culture media to study inducible laccase production on the same carbon sources. Inulinase and pectinase were also produced when Botryosphaeria sp. was grown on inulin, and galacturonic acid and pectin, respectively, and their levels were less in the presence of veratryl alcohol. Botryosphaeria sp. produced constitutive laccases on all carbon sources examined, and veratryl alcohol increased the laccase production on most of carbon sources studied except for inulin and galacturonic acid. Evidence is presented that Botryosphaeria sp. is also pectinolytic.
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PMID:The effect of carbohydrate carbon sources on the production of constitutive and inducible laccases by Botryosphaeria sp. 1296 81


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