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)

Reliable screening methods are being demanded by biocatalysts' engineers, especially when some features such as activity or stability are targets to improve under non-natural conditions (i.e., in the presence of organic solvents). The current work describes a protocol for the design of a fungal laccase-expressed in Saccharomyces cerevisiae-highly active in organic cosolvents. A high-throughput screening assay based on ABTS (2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)) oxidation was validated. The stability of the ABTS radical cation was not significantly altered in the presence of acetonitrile, ethanol, or DMSO. With a coefficient of variance below 10% and a sensitivity limit of 15 pg laccase/microL, the assay was reproducible and sensitive. The expression system of Myceliophthora thermophila laccase variant T2 in S. cerevisiae was highly dependent on the presence of Cu2+. Copper concentration was limited up to 10 microM CuSO4 where expression levels (approximately 14-18 mg/L) were acceptable without compromising the reliability of the assay. A mutant library was created by error-prone PCR with 1.1 to 3.5 mutations per kb. After only 1 generation of directed evolution, mutant 6C9 displayed about 3.5-fold higher activities than parent type in the presence of 20% acetonitrile or 30% ethanol. The method provided here should be generally useful to improve the activity of other redox enzymes in mixtures of water/cosolvents.
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PMID:Screening mutant libraries of fungal laccases in the presence of organic solvents. 1610 14

Laccase is one of the ligninolytic enzymes of white rot fungus Trametes versicolor 951022, a strain first isolated in Korea. This laccase was purified 209-fold from culture fluid with a yield of 6.2% using ethanol precipitation, DEAE-Sepharose, Phenyl-Sepharose, and Sephadex G-100 chromatography. T. versicolor 951022 excretes a single monomeric laccase showing a high specific activity of 91,443 U/mg for 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) as a substrate. The enzyme has a molecular mass of approximately 97 kDa as determined by SDS-PAGE, which is larger than those of other laccases reported. It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 3.0 and a temperature of 50 degrees C. The Km value of the enzyme for substrate ABTS is 12.8 micrometer and its corresponding Vmax value is 8125.4 U/mg. The specific activity and substrate affinity of this laccase are higher than those of other white rot fungi, therefore, it may be potentially useful for industrial purposes.
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PMID:Purification and characterization of laccase from the white rot fungus Trametes versicolor. 1641 Jul 73

We propose a new process using a vapor phase bioreactor (VPB) to simultaneously (i) delignify sugar-cane bagasse, a residue of sugar production that can be recycled in paper industry, and (ii) produce laccase, an enzyme usable to bleach paper pulp. Ethanol vapor, used as laccase inducer, was blown up through a VPB packed with bagasse and inoculated with Pycnoporus cinnabarinusss3, a laccase-hyperproducing fungal strain. After 28 days, the laccase activity in the ethanol-treated bagasse was 80-fold higher (80 U g(ds)(-)(1)) and the bagasse delignification percentage was 12-fold (12%) higher than in the reference samples produced in the absence of ethanol, corresponding to a high overall pulp yield of 96.1%. In the presence of ethanol, the total soluble phenols amount was 2.5-fold (3 mg FA g(ds)(-)(1)) higher than that without ethanol. Six monomeric phenols were detected: p-coumaric (4-hydroxyphenyl-2-propenoic), ferulic (4-hydroxy-3-methoxyphenyl-2-propenoic), syringic (4-hydroxy-3,5-dimethoxybenzoic), vanillic (4-hydroxy-3-methoxybenzoic) and 4-hydroxybenzoic acids, and 2-methoxyhydroquinone. Higher concentrations of phenolic compounds were observed when ethanol vapor was added, confirming a more efficient bagasse delignification. After 28 days, the fungal-treated bagasse (with ethanol addition) was pulped and refined. For a freeness of 81 mL CSF, this processing required 50% less energy than with untreated bagasse (without inoculation and ethanol addition), which indicated a significant potential economy for the pulp and paper industry. Handsheets were made from pulp obtained after fungal-treated and untreated bagasse. Comparison of bagasse-pulp characteristics for freeness of 35 and 181 mL CSF showed an average increment by 35% for tensile index and breaking strength and length. VPB allowed a simultaneous production of laccase (90 U g(ds)(-)(1), after pressing of the bagasse) that improved the overall profitability of the process.
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PMID:New process for fungal delignification of sugar-cane bagasse and simultaneous production of laccase in a vapor phase bioreactor. 1671 6

The characteristic biodegradation of monomeric styrene by Phanerochaete chrysosporium KFRI 20742, Trametes versicolor KFRI 20251 and Daldinia concentrica KFRI 40-1 was carried out to examine the resistance, its degradation efficiency and metabolites analysis. The estrogenic reduction effect of styrene by the fungi was also evaluated. The mycelium growth of fungi differentiated depending on the concentration levels of styrene. Additionally P. chrysosporium KFRI 20742 showed superior mycelium growth at less than 200 mg/l, while D. concentrica KFRI 40-1 was more than 200 mg/l. The degradation efficiency reached 99% during one day of incubation for all the fungi. Both manganese-dependent peroxidase and laccase activities in liquid medium were the highest at the initial stage of incubation, whereas the lowest was after the addition of styrene. However, both activities were gradually recovered after. The major metabolites of styrene by P. chrysosporium KFRI 20742 were 2-phenyl ethanol, benzoic acid, cyclohexadiene-1,4-dione, butanol and succinic acid. From one to seven days of incubating the fungi, the expression of pS2 mRNA widely known as an estrogen response gene was decreased down to the level of baseline after one day. Also, the estrogenic effect of styrene completely disappeared after treatment with supernatant of P. chrysosporium KFRI 20742 from one week of culture down to the levels of vehicle.
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PMID:Estrogenic reduction of styrene monomer degraded by Phanerochaete chrysosporium KFRI 20742. 1672 54

Oxidation of lignin obtained from acetosolv and ethanol/water pulping of sugarcane bagasse was performed by phenol oxidases: tyrosinase (TYR) and laccase (LAC), to increase the number of carbonyl and hydroxyl groups in lignin, and to improve its chelating capacity. The chelating properties of the original and oxidized lignins were compared by monitoring the amount of Cu2+ bound to lignin by gel permeation chromatography. The Acetosolv lignin oxidized with TYR was 16.8% and with LAC 21% higher than that of the original lignin. For ethanol/water lignin oxidized with TYR was 17.2% and with LAC 18% higher than that of the original lignin.
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PMID:Obtainment of chelating agents through the enzymatic oxidation of lignins by phenol oxidase. 1691 50

Sugarcane bagasse hydrolysis with 2.5% (v/v) HCl yielded 30.29g/L total reducing sugars along with various fermentation inhibitors such as furans, phenolics and acetic acid. The acid hydrolysate when treated with anion exchange resin brought about maximum reduction in furans (63.4%) and total phenolics (75.8%). Treatment of hydrolysate with activated charcoal caused 38.7% and 57.5% reduction in furans and total phenolics, respectively. Laccase reduced total phenolics (77.5%) without affecting furans and acetic acid content in the hydrolysate. Fermentation of these hydrolysates with Candida shehatae NCIM 3501 showed maximum ethanol yield (0.48g/g) from ion exchange treated hydrolysate, followed by activated charcoal (0.42g/g), laccase (0.37g/g), overliming (0.30g/g) and neutralized hydrolysate (0.22g/g).
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PMID:Detoxification of sugarcane bagasse hydrolysate improves ethanol production by Candida shehatae NCIM 3501. 1701 76

Wastewaters generated from the production of ethanol from sugar cane molasses may have detrimental effects on the environment due to their high chemical oxygen demand and dark brown color. The color is mainly associated with the presence of melanoidins, which are highly recalcitrant to biodegradation. We report here the induction of laccases by molasses wastewaters and molasses melanoidins in the basidiomycetous fungus Trametes sp. I-62. The time course of effluent decolorization and laccase activity in the culture supernatant of the fungus were correlated. The expression of laccase genes lcc1 and lcc2 increased as a result of the addition of complete molasses wastewater and its high molecular weight fraction to fungal cultures. This is the first time differential laccase gene expression has been reported to occur upon exposure of fungal cultures to molasses wastewaters and their melanoidins.
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PMID:Melanoidin-containing wastewaters induce selective laccase gene expression in the white-rot fungus Trametes sp. I-62. 1824 62

In company with the development of nonaqueous enzymology, the enzymatic modification of lignin has gained increasing interests, especially in the synthesis of high molecular material. In the present article, the enzymatic modification of spruce alkali lignin in cetyltrimethylammonium bromide (CTAB) reversed micelles (100 mmol x L(-1) 1, pH 6.0, W/O = 40), alcohol lignin in ethanol solution (50%), lignin sulphonate in sodium phosphate buffer (pH 5.8, 20 mmol x L(-1)) and steam-explosion wheat straw alkali lignin in alkaline solution (pH 10.0, 20 mmol x L(-1) NaOH) by mycelia sterilia YY-5 laccase was studied. Laccase was isolated from Mycelia Sterilia YY-5 (CGMCC-1462) which was an entophytic fungus of Rhus Chinensis Mill. FTIR spectrum was used to assay the structure of lignins and gel permeation chromatography (GPC) was used to determine the molecular weight and molecular weight polydispersity of lignins. Bands of lignin in FTIR spectra of all lignins changed obviously after treated with YY-5 laccase, which indicated that some bond breakage or rearrangement occurred to lignin. The shift of non-conjugated C=O and conjugated carbonyl groups (alpha-carbonyl groups) stretching vibration, the decrease of phenol hydroxyl stretching vibration and the increase of C--O--C stretching vibration of ester bond proved that phenolic hydroxyl, carbonyl group and side chain substituent all might participate in the laccase modification reactions of lignin. Meanwhile, the results of GPC indicated that the molecular of lignins all have certain increase and molecular polydispersity decreased. From the point of the molecular mass polydispersity, the modification effect of YY-5 laccase on steam-exploded wheat straw alkali lignin and spruce alkali lignin was more significantly than other two lignins. The molecular mass polydispersity for steam-exploded wheat straw alkali lignin and spruce alkali lignin was 1.211 and 1.375 respectively, which might contribute to the alkali-stable enzyme for YY-5 laccase. Correspondingly, alkali solution was chosen as the optimum medium for YY-5 laccase to modify lignins.
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PMID:[FTIR spectra analysis of the reactive activity of lignin when modified by laccase]. 1884 48

The spectrophotometric method of antioxidants determination using recombinant laccase Polyporus pinsitus (rPpL) and Myceliophthora thermophila (rMtL) was developed. The method includes simultaneous oxidation of the antioxidant and high reactive laccase substrate producing chromophoric radical cation. As laccase substrates ABTS and other high reactive phenoxazine derivatives: 2-phenoxazin-10-yl-ethanol (PET), 3-phenoxazin-10-yl-propane-1-sulfonic acid (PPSA) and 3-phenoxazin-10-yl-propionic acid (PPA) were used. The kinetic data were analysed using a scheme of simultaneous oxidation of the antioxidant and the substrate. In a range of (0.9-7.3)x10(-6)M of Trolox the measurings recovered 91 and 99% of the antioxidant if ABTS and both laccases were used. The recovery varied between 82 and 124% if phenoxazine derivatives were used. The antioxidant activity determined in rich with antioxidants food samples, i.e. date-palm, black raisin, golden raisin, skin of red grape, dice of red grape, fitted the literature data.
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PMID:Antioxidants determination with laccase. 1907 50

The influence of low doses of guaiacol and ethanol, the natural effectors of lignin and phenolics transformations, on laccase and peroxidase activities produced by two strains of Basidiomycetes, Pleurotus sajor-caju and Trametes versicolor, was evaluated. Fungal mycelia were grown for 2 weeks on liquid media containing serial dilutions of guaiacol or ethanol ranging from 100(-1) to 100(-20) mol/L. Laccase and peroxidase activities in the medium were measured at the end of 2 weeks. The effect of low doses of guaiacol and ethanol on enzyme activities was manifested in an oscillating manner. Similar response patterns were observed when pure enzymes were exposed to the same serial dilutions of guaiacol and ethanol. T. versicolor cultures enriched with 40 mmol guaiacol (simulating natural environmental conditions) also displayed oscillating enzyme activity patterns in response to serial dilutions of guaiacol, but the maximum enzyme activity values were increased compared to those observed in cultures not receiving 40 mmol guaiacol. The differences between maxima and minima varied among the experimental groups and depended on the species of fungus, type of effector, and kind of enzyme. The results suggest the possibility of subtle regulation of enzymatic activity on the molecular level.
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PMID:Effect of low doses of guaiacol and ethanol on enzymatic activity of fungal cultures. 1933 Jan 20


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