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)

The wood-degrading fungus Trametes multicolor secretes several laccase isoforms when grown on a simple medium containing copper in the millimolar range for stimulating laccase synthesis. The main isoenzyme laccase II was purified to apparent homogeneity from the culture supernatant by using anion-exchange chromatography and gel filtration. Laccase II is a monomeric glycoprotein with a molecular mass of 63 kDa as determined by sodium dodecylsulfate polyacrylamide gel electrophoresis, contains 18% glycosylation, and has a pI of 3.0. It oxidizes a variety of phenolic substrates as well as ferrocyanide and iodide. The pH optimum depends on the substrate employed and shows a bell-shaped pH activity profile with an optimum of 4.0 to 5.0 for the phenolic substrates, while the nonphenolic substrates ferrocyanide and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) show a monotonic pH profile with a rate decreasing with increasing pH.
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PMID:Purification and characterization of a laccase from the white-rot fungus Trametes multicolor. 1201 76

The Psc lac4 gene from Pleurotus sajor-caju has been cloned and expressed in the heterologous host Pichia pastoris, under the control of the AOX1 methanol inducible promoter. The native Ple. sajor-caju laccase signal sequence was effective in directing the secretion of lac4 expressed in Pic. pastoris. The control of media pH and temperature was found to be important in obtaining sufficient quantities of the protein to allow purification and subsequent biochemical characterization. The recombinant Psc Lac4 was purified to electrophoretic homogeneity and was shown to be immunologically related to Pleurotus eryngii Lac1. The purified laccase was estimated to have a molecular mass of around 59 kDa, to have a carbohydrate content of approximately 7% and a calculated pI of 4.38. The enzyme oxidized the substrates 2,2-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), 2,6-dimethoxyphenol, syringaldazine and guaiacol, exhibiting optimal pHs of 3.3, 6, 6.5 and 7 respectively. With ABTS as substrate the enzyme displayed optimal activity at 35 degrees C and pH 3.5. The enzyme was strongly inhibited by sodium azide and thioglycolic acid but not by EDTA.
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PMID:Molecular cloning of a laccase isozyme gene from Pleurotus sajor-caju and expression in the heterologous Pichia pastoris host. 1248 Sep 4

Poly(catechol) was synthesized in batch runs with laccase from Trametes versicolor (ATCC 200801). The polymerization reaction was conducted in a closed, temperature controlled system containing acetone and sodium acetate buffer for pH control. The effects of the solvent mixture, monomer (catechol), enzyme, medium pH and temperature on the polymerization rate were investigated with respect to initial reaction conditions and depletion rate of dissolved oxygen in the medium. Maximum initial reaction rate was attained with 10% (v/v) acetone-sodium acetate buffer at pH 5.0, 25 degrees C, 0.02 U/ml enzyme and 250 mg/l initial catechol and 10 mg/l dissolved oxygen. A general saturation enzyme kinetics response was observed for catechol substrate. Temperature rise supported the rate increase up to 45 degrees C, after which the rate tended to be stable due to a drop in dissolved oxygen concentration as well as enzyme instability.
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PMID:Reaction conditions for laccase catalyzed polymerization of catechol. 1250 58

A new laccase (EC 1.10.3.2) produced by Streptomyces cyaneus CECT 3335 in liquid media containing soya flour (20 g per liter) was purified to homogeneity. The physicochemical, catalytic, and spectral characteristics of this enzyme, as well as its suitability for biobleaching of eucalyptus kraft pulps, were assessed. The purified laccase had a molecular mass of 75 kDa and an isoelectric point of 5.6, and its optimal pH and temperature were 4.5 and 70 degrees C, respectively. The activity was strongly enhanced in the presence of Cu(2+), Mn(2+), and Mg(2+) and was completely inhibited by EDTA and sodium azide. The purified laccase exhibited high levels of activity against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and 2,6-dimethoxyphenol and no activity against tyrosine. The UV-visible spectrum of the purified laccase was the typical spectrum of the blue laccases, with an absorption peak at 600 nm and a shoulder around 330 to 340 nm. The ability of the purified laccase to oxidize a nonphenolic compound, such as veratryl alcohol, in the presence of ABTS opens up new possibilities for the use of bacterial laccases in the pulp and paper industry. We demonstrated that application of the laccase from S. cyaneus in the presence of ABTS to biobleaching of eucalyptus kraft pulps resulted in a significant decrease in the kappa number (2.3 U) and an important increase in the brightness (2.2%, as determined by the International Standard Organization test) of pulps, showing the suitability of laccases produced by streptomycetes for industrial purposes.
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PMID:Kraft pulp biobleaching and mediated oxidation of a nonphenolic substrate by laccase from Streptomyces cyaneus CECT 3335. 1267 69

The wood-degrading fungus Pleurotus pulmonarius produces at least two laccase isoforms, Lcc1 and Lcc2, when grown on wheat bran solid state medium. The main laccase, Lcc2, was purified to apparent electrophoretic homogeneity by using acetone precipitation, anion-exchange chromatography and gel filtration. Lcc2 had been purified 5.9-fold with a yield of 49%. A specific activity of 19750 U/mg protein was found using syringaldazine as a substrate under standard assay conditions. The enzyme is a homodimeric glycoprotein containing 44% glycosilation and an apparent molecular mass of 46 kDa. Type I and type III Cu(2+) centers were identified by spectrophotometry. The laccase showed optimal activity at pH 6.2-6.5, 4.0-5.5, and 6.0-8.0 with syringaldazine, ABTS and guaiacol as substrates, respectively. For all substrates, the highest oxidation rates were obtained at 50 degrees C. The enzyme was stable over a large range of pH (4.5-8.0) and at temperatures up to 50 degrees C. Under standard assay conditions, the apparent K(M) values were 12, 210 and 550 microM for syringaldazine, ABTS and guaiacol, respectively. Purified Lcc2 was strongly inhibited by sodium azide, 2-mercaptoethanol and Hg(2+), and slightly inhibited by Mn(+2) and the chelant agents, EDTA and EGTA. The enzyme was activated by Cu(2+) and it retained a high percentage of its activity in the presence of organic solvents, such as acetonitrile and acetone.
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PMID:Purification and characterization of the main laccase produced by the white-rot fungus Pleurotus pulmonarius on wheat bran solid state medium. 1287 9

The white-rot fungus Daedalea quercina produced the ligninolytic enzymes laccase and Mn-dependent peroxidase. Laccase was purified using anionexchange and size-exclusion chromatographies. SDS-PAGE showed the purified laccase to be a monomeric protein of 69 kDa (71 kDa using gel filtration) with an isoelectric point near 3.0. The optimum pH for activity was below 2.0 for 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (K(m)=38 microM), 4.0 for 2,6-dimethoxyphenol (K(m)=48 microM), 4.5 for guaiacol (K(m)=93 microM) and 7.0 for syringaldazine (K(m)=131 microM). The temperature optimum was between 60 and 70 degrees C depending on the pH and buffer used. The enzyme was stable up to 45 degrees C, and stability was higher at alkaline pH. Enzyme activity was increased by the addition of Cu(2+) and inhibited by Mn(2+), sodium azide, dithiothreitol, and cysteine. Laccase from Daedalea quercina was able to decolorize the synthetic dyes Chicago sky blue, poly B-411, remazol brilliant blue R, trypan blue and reactive blue 2.
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PMID:Purification and characterization of laccase from the white-rot fungus Daedalea quercina and decolorization of synthetic dyes by the enzyme. 1450 38

Lignin degradation by the white rot basidiomycete Phanerochaete chrysosporium involves various extracellular oxidative enzymes, including lignin peroxidase, manganese peroxidase, and a peroxide-generating enzyme, glyoxal oxidase. Recent studies have suggested that laccases also may be produced by this fungus, but these conclusions have been controversial. We identified four sequences related to laccases and ferroxidases (Fet3) in a search of the publicly available P. chrysosporium database. One gene, designated mco1, has a typical eukaryotic secretion signal and is transcribed in defined media and in colonized wood. Structural analysis and multiple alignments identified residues common to laccase and Fet3 sequences. A recombinant MCO1 (rMCO1) protein expressed in Aspergillus nidulans had a molecular mass of 78 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the copper I-type center was confirmed by the UV-visible spectrum. rMCO1 oxidized various compounds, including 2,2'-azino(bis-3-ethylbenzthiazoline-6-sulfonate) (ABTS) and aromatic amines, although phenolic compounds were poor substrates. The best substrate was Fe2+, with a Km close to 2 micro M. Collectively, these results suggest that the P. chrysosporium genome does not encode a typical laccase but rather encodes a unique extracellular multicopper oxidase with strong ferroxidase activity.
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PMID:A novel extracellular multicopper oxidase from Phanerochaete chrysosporium with ferroxidase activity. 1453 88

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic organic pollutants widely distributed in terrestrial and aquatic environments. In the present work, 2 colorimetric assays for laccase-catalyzed degradation of PAHs were developed based on studies of the oxidation of 12 aromatic hydrocarbons by fungal laccases from Trametes versicolor and Myceliophthora thermophila. Using a sodium borohydride water-soluble solution, the authors could reduce the single product of laccase-catalyzed anthracene biooxidation into the orange-colored 9,10-anthrahydroquinone, which is quantifiable spectrophotometrically. An assay using polymeric dye (Poly R-478) as a surrogate substrate for lignin degradation by laccase in the presence of mediator is also presented. The decolorization of Poly R-478 was correlated to the oxidation of PAHs mediated by laccases. This demonstrates that a ligninolytic indicator such as Poly R-478 can be used to screen for PAH-degrading laccases; it will also be useful in screening mutant libraries in directed evolution experiments. Poly R-478 is stable and readily soluble. It has a high extinction coefficient and low toxicity toward white rot fungi, yeast, and bacteria, which allow its application in a solid-phase assay format.
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PMID:Colorimetric assays for biodegradation of polycyclic aromatic hydrocarbons by fungal laccases. 1459 53

The screening of potential redox mediators for laccase was performed using homogeneous enzyme preparations from Coriolus hirsutus and Coriolus zonatus. It was discovered that derivatives of 1-phenyl-3-methyl-pyrazolones were efficient substrates for the laccases. The characterization of two representatives of the 1-phenyl-pyrazolone class, sodium 1-phenyl-3-methyl-4- methylamino-pyrazolone-5-N(4)-methanesulfonate and 1-(3'-sulfophenyl)-3- methylpyrazolone-5, in the reaction catalyzed by laccase was carried out using spectral, electrochemical, and enzyme kinetics methods. The kinetic parameters for the oxidation of the newly discovered substrates were comparable with those for 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) oxidation by laccase. Electrochemical experiments demonstrated that oxidation of these compounds yielded two high-potential intermediates capable of oxidizing veratryl alcohol, which was used as a lignin model substrate, to the corresponding aldehyde and acid. 1-(3'-Sulfophenyl)-3- methylpyrazolone-5 was about 30-40% as effective in degrading veratryl alcohol compared to ABTS as judged from high-performance liquid chromatography kinetic studies. 1-Phenyl-3-methyl-pyrazolones may be of commercial interest for oxidoreductase-catalyzed biodegradation of organic compounds.
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PMID:Novel laccase redox mediators: spectral, electrochemical, and kinetic properties. 1466 36

An approach was developed to screening organic compounds for putative activity of redox mediators of oxidoreductases, including laccases and peroxidases, applicable for xenobiotic degradation. The study was carried out with a homogenous laccase preparation from the basidiomycete Trametes hirsuta and horse-radish root peroxidase. Compounds belonging to 1-phenyl-3-methylpyrazolones were selected. Spectroscopic and electrochemical investigation of two of the compounds, sodium 1-phenyl-2,3-dimethyl-4-aminopyrazolon 5n(4)-methanesulfonate (PPNa) and 1-(3'-sulfophenyl)-3-methylpyrazolone (SPP), was performed. Electrochemical oxidation of both PPNa and SPP gave rise to high-potential intermediates capable of oxidizing veratryl alcohol; a lignin-modeling compound. Kinetic indices of these compounds were determined in enzymatic reactions with the presence of laccase. It was shown that enzymatic oxidation of SPP by laccase produced high-potential intermediates capable of oxidizing veratryl alcohol to veratric acid. Veratryl alcohol did not oxidize during enzymatic oxidation of SPP by peroxidase. This points to a difference between the mechanisms of enzymatic oxidation of PPNa and SPP by laccase and peroxidase.
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PMID:[Phenyl pyrazolones--novel oxidoreductase redox-mediators for degradation of xenobiotics]. 1512 93


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