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

Addition of copper (0.5-5 mM) or cadmium (1-5 mM) to the white rot fungus Pleurotus ostreatus cultivated in liquid nitrogen-limited medium for 12 days increased the activity of laccase. The addition of 2 mM Cd led to an 18.5-fold increase of activity, 1 mM Cu increased the activity eight-fold. When added earlier than 12 days, the activation of laccase was delayed (Cu) or decreased (Cd). Ag, Hg, Pb, Zn, and H(2)O(2) decreased laccase activity. To study the effect on native enzymes, purified laccase was incubated with Cd, Cu, and Hg. The addition of Hg decreased the activity of laccase immediately and reduced the temporal stability of the enzyme, while the addition of Cu (0.05-50 mM) increased both enzyme activity and stability. Laccase extracted at different stages of straw colonisation differed in its response to heavy metals.
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PMID:Copper and cadmium increase laccase activity in Pleurotus ostreatus. 1178 59

White-rot fungus AH28-2, a newly isolated strain, produced effectively laccase by induction when grown on a synthetic medium. Aromatic compounds of low molecular weight had an inducing influence on laccase production and its isoenzyme compositions. The using of o-toluidine or syringic acid had the best inducing effect. Cu2+ concentration in medium had distinguished effect on laccase production. Enzyme activity was notably increased by Cu2+ and reached the maximum when Cu2+ final concentration was 5 mumol/L. Mn2+ inhibited the synthesis of laccase. Carbon and nitrogen limitation were not beneficial to laccase synthesis, while high nutrient organic medium was beneficial to the growth of cell and the synthesis of laccase. Using cellobiose as the sole carbon source, the highest level enzyme activity reached 82,923. 7 u/L under the condition of optimum fermentation with ABTS as substrate. This enzyme activity was 2.9-fold higher compared to the reported data on international references in recent years.
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PMID:[Factors of laccase producing and fermentation conditions by a new white-rot fungus AH28-2]. 1179 26

The white-rot fungus Trametes multicolor MB 49 has been identified as an excellent producer of the industrially important enzyme laccase. The formation of extracellular laccase could be considerably stimulated by the addition of Cu(II) to a simple, glycerol-based culture medium. In this study, optimal concentrations of copper were found to be 0.5-1 mM, which were added during the growth phase of the fungus. Other medium components important for laccase production are the carbon and nitrogen sources employed. When using an optimized medium containing glycerol (40 g/L), peptone from meat (15 g/L), and MgSO4 x 7H2O and stimulating enzyme formation by the addition of 1.0 mM Cu, maximal laccase activities obtained in shake-flask cultures were approx 85 U/mL. These results, however, could not be scaled up to a laboratory fermentor cultivation. Laccase production by T. multicolor decreased considerably when the fungus was grown in a stirred-tank reactor, presumably because of damage of the mycelia caused by shear stress and/or changes in the morphology of the fungus.
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PMID:Enhanced formation of extracellular laccase activity by the white-rot fungus Trametes multicolor. 1201 50

The effects of the carbon and nitrogen sources, initial pH and incubation temperature on laccase production by Trametes modesta were evaluated using the one-factor-at-a-time method. The final optimisation was done using a central composite design resulting in a four-fold increase of the laccase activity to 178 nkat ml(-1). Response-surface analysis showed that 7.34 g l(-1) wheat bran, 0.87 g l(-1) glucose, 2.9 g l(-1) yeast extract, 0.25 g l(-1) ammonium chloride, an initial pH of 6.95 and an incubation temperature of 30.26 degrees C were the optimal conditions for laccase production. Laccase produced by T. modesta was fully active at pH 4 and at 50 degrees C. The laccase was very stable at pH 4.5 and at 40 degrees C but half-lives decreased to 120 and 125 min at higher temperature (60 degrees C) and lower pH (pH 3).
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PMID:Production of laccase by a newly isolated strain of Trametes modesta. 1211 3

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

The ability of the ligninolytic fungus Trametes trogii to degrade in vitro different xenobiotics (PCBs, PAHs and dyes) was evaluated. Either 200 ppm of a PCB mixture (Aroclor 1150) or 160 ppm of an industrial PAH mixture (10% V/V of PAHs, principal components hexaethylbenzene, naphthalene, 1-methyl naphthalene, acenaphthylene, anthracene, fluorene and phenanthrene), were added to trophophasic and idiophasic cultures growing in a nitrogen limited mineral medium (glucose/asparagine) and in a complex medium (malt extract/glucose). Gas-liquid chromatography proved that within 7 to 12 d more than 90% of the organopollutants added were removed. The decrease in absorbance at 620 nm demonstrated that cultures of this fungus were able to transform 80% of the dye Anthraquinone-blue (added at a concentration of 50 ppm) in 1.5 h. Enzyme estimations indicated high activity of laccase (up to 0.55 U/mL), as well as lower production of manganese-peroxidase. Laccase activity, detected in all the conditions assayed, could be implicated in the degradation of these organopollutants. Considering the results obtained, T. trogii seems promising for detoxification.
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PMID:Degradation of environmental pollutants by Trametes trogii. 1241 98

Twenty-six species of ammonia fungi comprising 71 strains were screened for ligninolytic activity using agar plate tests. The tests comprised a wood powder plate test, the Bavendamm reactions, and a Remazol Brilliant blue R (RBBR) decolorization test. The wood powder plate test detected phenol oxidases of Coprinus spp., whereas this method obviously detected no activities from facultative mycorrhizal fungi, such as Hebeloma radicosoides and ectomycorrhiza: H. spoliatum and H. vinosophyllum. With quantitative assays of ligninolytic activity, Coprinus phlyctidosporus, C. echinosporus, Lyophyllum tylicolor, Lepista nuda, L. tarda, Calocybe leucocephala, and Crucispora rhombisperma, which grow on oak-leaf litter, the major phenol-oxidizing enzyme was a laccase. The concentration of urea affected laccase activity; however, urea was not the obligate nitrogen source for the laccase production.
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PMID:Some characteristics of ammonia fungi 1. In relation to their ligninolytic enzyme activities. 1250 13

A cDNA coding for laccase was isolated from the white-rot fungus Trametes trogii 201. This cDNA corresponded to the lcc1 gene, which coded for a precursor protein of 517 amino acids with a 21 amino acid signal peptide. Comparison of the deduced sequence with known laccases showed that this enzyme was most closely related to Lac1 from basidiomycete PM1 and Trametes C30 (98% similarity). The expression of lcc1 was analysed under different growth conditions; transcription of this gene was enhanced by the addition of organic nitrogen to the medium. The level of lcc1 transcription was higher when T. trogii was grown on synthetic medium supplemented with yeast extract rather than mycological peptone or tryptone. The transcription data were in agreement with total laccase activity measured in the supernatant and suggested that laccase production and lcc1 transcription are coordinately regulated in this organism. The lcc1 cDNA was expressed in the methylotrophic yeast Pichia pastoris and the detection of laccase activity indicated that this cDNA encodes a laccase.
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PMID:Primary structure and transcription analysis of a laccase-encoding gene from the basidiomycete Trametes trogii. 1368 Feb 1

The reaction of the monomeric lignin model compound guaiacol and the beta-O-4-type dimer erol (1-(4-hydroxy-3-methoxyphenyl)-2(2-methoxyphenoxy)-propane-1,3-diol with laccase from Trametes hirsuta was studied in the presence of the mediator ABTS (2,2'-azino-di[3ethylbenzothiazoline-6-sulfonic acid]). The product mixtures were analyzed by means of aqueous-phase size exclusion chromatography (SEC) with 50 mM NaOH as eluent. Interestingly, in the laccase-catalyzed reaction with both substrates, the mediator not only functioned as an electron carrier but underwent coupling reactions with the substrate to give polymeric coupling products. The molecular weight of these copolymeric products was significantly higher than the molecular weight of products obtained without ABTS. After ultrafiltration, 33% and 21% of the initially applied ABTS could be found in the polymeric product fraction for the substrates guaiacol and erol, respectively, on the basis of nitrogen analysis. When ABTS was added to substrates after full laccase-catalyzed polymerization, the reaction proceeded toward higher molecular weights.
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PMID:Polymerization of guaiacol and a phenolic beta-O-4-substructure by Trametes hirsuta laccase in the presence of ABTS. 1452 12


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