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

White-rot fungi (WRF) are ubiquitous in nature with their natural ability to compete and survive. WRF are the only organisms known to have the ability to degrade and mineralize recalcitrant plant polymer lignin. Their potential to degrade second most abundant carbon reserve material lignin on the earth make them important link in global carbon cycle. WRF degrade lignin by its unique ligninolytic enzymatic machinery including lignin peroxidase, manganese peroxidase, laccase, cellobiose dehydrogenase, H2O2-generating enzymes, etc. The ligninolytic enzymes system is non-specific, extracellular and free radical based that allows them to degrade structurally diverse range of xenobiotic compounds. Lignin peroxidase and manganese peroxidase carry out direct and indirect oxidation as well as reduction of xenobiotic compounds. Indirect reactions involved redox mediators such as veratryl alcohol and Mn2+. Reduction reactions are carried out by carboxyl, superoxide and semiquinone radicals, etc. Methylation is used as detoxification mechanism by WRF. Highly oxidized chemicals are reduced by transmembrane redox potential. Degradation of a number of environmental pollutants by ligninolytic system of white rot fungi is described in the present review.
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PMID:Degradation of xenobiotic compounds by lignin-degrading white-rot fungi: enzymology and mechanisms involved. 1587 13

Pleurotus ostreatus produces the cellulolytic and hemicellulolytic enzymes endo-1,4-beta-glucanase, exo-1,4-beta-glucanase, 1,4-beta-glucosidase, endo-1,4-beta-xylanase, 1,4-beta-xylosidase, endo-1,4-beta-mannanase and 1,4-beta-mannosidase and ligninolytic enzymes Mn-peroxidase and laccase during growth on wheat straw in the presence and absence of Cu, Mn, Pb, and Zn. This is the first report concerning endo-1,4-beta-mannanase in P. ostreatus. Although the concentrations of trace metals in wheat straw ranged from units to tens of microg g(-1), only 3-6% (Fe, Pb) or 30-45% (Cu, Mn, Zn) of the total amount was extractable and available for the fungus. The substrate colonization rate was only decreased by high concentrations of Cu and Zn; the loss of dry mass differed among treatments in the initial phase of fungal growth, and at the end of the experiment (day 98) it was significantly lower in metal-containing treatments (63-66%) than in the control (70%). The cellulolytic and hemicellulolytic enzyme were prone to a metal effect except for the increase in endo-1,4-beta-glucanase and 1,4-beta-glucosidase in the presence of Zn. Laccase activity was increased by all tested metals, and unlike other white-rot fungi, Mn-peroxidase levels were low in the presence of manganese.
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PMID:Degradation of lignocellulose by Pleurotus ostreatus in the presence of copper, manganese, lead and zinc. 1592 94

A strain of fungi was isolated from soil, which was identified as Penicillium simplicissimum. This strain was capable of utilizing several lignin model compounds, making aromatic dyes decoloration and degrading natural lignin. All these results proved that Penicillium simplicissimum has ligninolytic ability. Three kinds of enzymes were believed to be the most important catalyzes in the biodegrading process. They are lignin peroxidase (LiP), laccase (Lac) and hemicellulase. And they always work synergistically. After 25 days' incubation, the amount of rice straw lignin decreased 0.23g, and the degrading rate was 14.94%. Different from the degrading mechanism of the white-rot fungi, the lignin degradation by P. simplicissimum mainly happened during the primary metabolism and it was greatly influenced by the pH of media, the concentration of Cu2+ and Mn2+.
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PMID:[Lignin degradation by Penicillium simplicissimum]. 1600 22

In order to decolourise olive oil mill wastewaters (OOMW) efficiently, production and differential induction of ligninolytic enzymes by the white rot Coriolopsis polyzona, were studied by varying growth media composition and/or inducer addition. Among various possible inducers, veratryl alcohol appeared to be the most efficient to enhance specific productions of lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase by a factor of 18.5, 20.8 and 55, respectively. Ligninolytic enzymes were better produced in glucose based medium with a low nitrogen level (2.2 mM) under O2 atmosphere. The addition of 5 mM veratryl alcohol resulted in a maximal production of LiP, whereas maximal MnP and laccase were obtained at 10 mM. LiP production was totally repressed in presence of 100 microM Mn2+. The extrapolation of these conditions on OOMW based media was carried out at different effluent dilutions and the possible role of the different ligninolytic enzymes in OOMW decolourisation was studied. A better effluent decolourisation was obtained under LiP induction condition (5 mM veratryl alcohol) than when LiP was repressed (100 microM Mn2+). Furthermore, high levels of laccase had a detrimental effect on OOMW decolourisation concomitant to the formation of soluble polymeric aromatic compounds.
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PMID:Lignin modifying enzymes of Coriolopsis polyzona and their role in olive oil mill wastewaters decolourisation. 1603 61

The extracellular ligninolytic enzyme system of Pleurotus laciniatocrenatus, grown under different culture conditions, was characterized and the ability of this strain to degrade different components of Eucalyptus globulus wood was determined. In shaken liquid cultures grown on a C-limited medium supplemented with yeast extract (0.1%) and peptone (0.5%), the fungus produced extracellular aryl-alcohol oxidase (Aao), laccase (Lac), manganese-dependent peroxidase (MnP) and manganese-independent peroxidase (MiP) activities, their maximum levels being, respectively, about 600, 50, 1360, and 920 pkat/mL. The supplementation of 1 mmol/L vanillic acid and 150 micromol/L CuSO4 produced an increase of Lac activity levels up to 4-fold and 68.3-fold, respectively. No significant differences were found in the levels of the other ligninolytic enzyme activities when compared to the basal medium. Solid-state fermentation cultures on E. globulus wood chips revealed Lac and MiP activities. These cultures showed degradative activity on lignin and lipophilic wood extractives.
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PMID:Ligninolytic ability and potential biotechnology applications of the South American fungus Pleurotus laciniatocrenatus. 1611 Sep 21

Laccase produced by Basidiomycete was purified to electrophoretic homogeneity by the steps of ammonium sulfate precipitation, DEAE-cellulose and hydrophobic interaction column chromatography. Purification of about 318.4 fold was achieved with an overall yield of 18.6%. Its molecular weight was estimated to be about 60.3 kD by SDS-PAGE, and that of it was 55.94 kD by mass spectrum. The optimum temperature and pH of the enzyme activity were 65 degrees C and 2.2 - 2.8 respectively. The isoelectric point was 4.02 (room temperature). Its N-terminal sequence was AIGPVTDL. The carbohydrate content was 49.2% by the phenol-sulfuric acid method. Michaelis constant of the enzyme for ABTS was 17.5 micromol/L. The enzyme activity was stable under 45 degrees C and in the pH range of 3.0 - 9.5. The activity was enhanced by Cu2+, and was strongly inhibited by Fe2+. While Mn2+ and Ag+ had no effect on laccase activity. Dithiothreitol and sodium azide inhibited completely the activity. Trp was possible essential residue for enzyme activity.
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PMID:[Purification and properties of laccase from Basidiomycete]. 1627 74

Effect of different nitrogen concentration in the mediums on growth and enzyme production of Phanerochaete chrysosporium was studied when glucose concentration was 10 g/L. The results showed that the medium contained 0.8 g/L ammonium tartrate is the best. It not only supply abundant nutrients for the growth of Phanerochaete chrysosporium, which make mycelia the best grow compared with the other medium, but also produce higher manganese-dependent peroxidase (Mnp) and laccase (Lac) activity. In addition, it is observed that the variation of mycelia surface is related to ligninolytic enzyme secreted by Phanerochaete chrysosporium. When the surface of mycelium pellets appeared burs, it predicts secondary metabolism begin. This experimentation demonstrated that when the ratio of carbon and nitrogen in nitrogen limited medium is equal to 100:8, growth and enzyme production of Phanerochaete chrysosporium is the best, it could achieve the maximum Mnp and Lac activity.
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PMID:Effect of nitrogen concentration in culture mediums on growth and enzyme production of Phanerochaete chrysosporium. 1629 86

Recently, Mn(II) has been shown to induce manganese peroxidases (MnPs) and repress lignin peroxidases (LiPs) in defined liquid cultures of several white rot organisms. The present work shows that laccase is also regulated by Mn(II). We therefore used Mn(II) to regulate production of LiP, MnP, and laccase activities while determining the effects of Mn(II) on mineralization of ring-labeled synthetic lignin. At a low Mn(II) level, Phanerochaete chrysosporium and Phlebia brevispora produced relatively high titers of LiPs but only low titers of MnPs. At a high Mn(II) level, MnP titers increased 12- to 20-fold, but LiPs were not detected in crude broths. P. brevispora formed much less LiP than P. chrysosporium, but it also produced laccase activity that increased more than sevenfold at the high Mn(II) level. The rates of synthetic lignin mineralization by these organisms were similar and were almost seven times higher at low than at high Mn(II). Increased synthetic lignin mineralization therefore correlated with increased LiP, not with increased MnP or laccase activities.
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PMID:Mineralization of C-Ring-Labeled Synthetic Lignin Correlates with the Production of Lignin Peroxidase, not of Manganese Peroxidase or Laccase. 1634 21

Transformation of veratric (3,4-dimethoxybenzoic) acid by the white rot fungus Phlebia radiata was studied to elucidate the role of ligninolytic, reductive, and demeth(ox)ylating enzymes. Under both air and a 100% O(2) atmosphere, with nitrogen limitation and glucose as a carbon source, reducing activity resulted in the accumulation of veratryl alcohol in the medium. When the fungus was cultivated under air, veratric acid caused a rapid increase in laccase (benzenediol:oxygen oxidoreductase; EC 1.10.3.2) production, which indicated that veratric acid was first demethylated, thus providing phenolic compounds for laccase. After a rapid decline in laccase activity, elevated lignin peroxidase (ligninase) activity and manganese-dependent peroxidase production were detected simultaneously with extracellular release of methanol. This indicated apparent demethoxylation. When the fungus was cultivated under a continuous 100% O(2) flow and in the presence of veratric acid, laccase production was markedly repressed, whereas production of lignin peroxidase and degradation of veratryl compounds were clearly enhanced. In all cultures, the increases in lignin peroxidase titers were directly related to veratryl alcohol accumulation. Evolution of CO(2) from 3-OCH(3)-and 4-OCH(3)-labeled veratric acids showed that the position of the methoxyl substituent in the aromatic ring only slightly affected demeth(ox)ylation activity. In both cases, more than 60% of the total C was converted to CO(2) under air in 4 weeks, and oxygen flux increased the degradation rate of the C-labeled veratric acids just as it did with unlabeled cultures.
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PMID:Formation and Action of Lignin-Modifying Enzymes in Cultures of Phlebia radiata Supplemented with Veratric Acid. 1634 72

The white rot fungi Lentinula edodes, Phanerochaete chrysosporium, Pleurotus sajor-caju, Flammulina velutipes, and Schizophyllum commune were grown in liquid media containing C-lignin-labelled wood, and the formation of water-soluble C-labelled products and CO(2), the growth of the fungi, and the activities of extracellular lignin peroxidase, manganese peroxidase, and laccase were measured. Conditions that affect the rate of lignin degradation were imposed, and both long-term (0- to 16-day) and short-term (0- to 72-h) effects on the production of the two types of product and on the activities of the enzymes were monitored. The production of CO(2)-labelled products from the aqueous ones was also investigated. The short-term studies showed that the different conditions had different effects on the production of the two products and on the activities of the enzymes. Nitrogen sources inhibited the production of both products by all species when differences in growth could be discounted. Medium pH and manganese affected lignin degradation by the different species differently. With P. chrysosporium, the results were consistent, with lignin peroxidase playing a role in lignin solubilization and manganese peroxidase being important in subsequent CO(2) production.
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PMID:Solubilization and mineralization of lignin by white rot fungi. 1634 81


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