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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 laccase (EC 1.10.3.2) was isolated from the fully browned gills of Lentinula edodes fruit bodies. The enzyme was purified to a homogeneous preparation using hydrophobic, cation-exchange and size-exclusion chromatography. SDS-PAGE analysis showed the purified laccase, Lcc 2, to be a monomeric protein of 58.0 kDa. The enzyme had an isoelectric point of around pH 6.9. The optimum pH for enzyme activity was around 3.0 against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS), and it was most active at 40 degrees C and stable up to 50 degrees C. The enzyme contained 8.6 % carbohydrate and some copper atoms. The enzyme oxidized ABTS, p-phenylenediamine, pyrogallol, guaiacol, 2,6-dimethoxyphenol, catechol and ferulic acid, but not veratryl alcohol and tyrosine. Beta-(3,4-dihydroxyphenyl)alanine (L-DOPA), which was not oxidized by a laccase previously reported from the culture filtrate of L. edodes, was also oxidized by Lcc 2, and the oxidative product of L-dopa was identified as L-DOPA quinone by HPLC analysis. Lcc 2 was able to oxidize phenolic compounds extracted from fresh gills to brown-coloured products, suggesting a role for laccase in melanin synthesis in this strain.
Microbiology (Reading) 2003 Sep
PMID:Important role of fungal intracellular laccase for melanin synthesis: purification and characterization of an intracellular laccase from Lentinula edodes fruit bodies. 1294 71

The 1H NMR spectra of the fully oxidized Rhus vernicifera laccase and of its 1:1 and 2:1 azide adducts are reported for the first time. These spectra, which are the first so far reported for a multi copper oxidase, contain a number of broad hyperfine-shifted resonances in the high frequency region of the spectrum, which are attributed to the metal binding residues of the mononuclear T1 center. The differences between the patterns of the hyperfine resonances of the free enzyme and its azide derivatives suggest that the alterations in the structural properties of the T3 site induced by the binding of the first azide molecule induce a limited alteration of the spin density distribution over the T1 copper ligands. Overall, these data demonstrate that 1H NMR can be fruitfully applied to characterize the electronic properties of the metal sites of blue oxidases at room temperature.
J Inorg Biochem 2003 Sep 01
PMID:1H NMR of native and azide-inhibited laccase from Rhus vernicifera. 1367 17

Reactive Black 5 industrial dyeing effluent was decolourized by free and immobilized laccase. The stability of the enzyme (194 h free and 79 h immobilized) depended on the dyeing liquor composition and the chemical structure of the dye. In the decolourization experiments with immobilized laccase, two phenomenons were observed--decolourization due to adsorption on the support (79%) and dye degradation due to the enzyme action (4%). Dyeing in the enzymatically recycled effluent provided consistency of the colour with both bright and dark dyes.
Biotechnol Lett 2003 Sep
PMID:Immobilized laccase for decolourization of Reactive Black 5 dyeing effluent. 1451 53

Increased manganese concentration during submerged cultivation of the ligninolytic white rot fungus Panus tigrinus 8/18 on N-limited mineral medium resulted in the induction of Mn-peroxidase and laccase. The Mn-peroxidase was purified with the purity factor RZ (A(406)/A(280)) = 4.3. The purified enzyme catalyzed H2O2-dependent oxidation of phenol oxidase substrates (aromatic amines, 2,2;-azinobis-(3-ethylbenzthiazolinesulfonic acid), hydroquinone, 2,6-dimethoxyphenol) without Mn2+, which is not typical for the usual Mn-peroxidases. Guaiacol and 2,4,6-trichlorophenol were not oxidized in the absence of Mn2+. Study of absorption spectra of the intermediates of the catalytic cycle revealed that this peroxidase is able to complete the redox cycle, reducing one-electron oxidized intermediate (Compound II) by Mn2+, as well as by an organic substrate (hydroquinone). This means that the enzyme is a "hybrid" Mn-peroxidase, different from the common Mn-peroxidases from ligninolytic fungi.
Biochemistry (Mosc) 2003 Sep
PMID:Hybrid Mn-peroxidase from the ligninolytic fungus Panus tigrinus 8/18. Isolation, substrate specificity, and catalytic cycle. 1460 47

The ability of the white-rot fungus Lentinula (Lentinus) edodes to decolorize several synthetic dyes was investigated using solid state cultures with corn cob as substrate. Cultures, containing amido black, congo red, trypan blue, methyl green, remazol brilliant blue R, methyl violet, ethyl violet and Poly R478 at 200 ppm, were completely decolorized after 18 days of incubation. Partial decolorization was observed in the cultures containing 200 ppm of brilliant cresyl blue and methylene blue. High manganese peroxidase activity (2600 U/g substrate), but very low lignin peroxidase (<10 U/g substrate) and laccase (<16 U/g substrate) activities were detected in the cultures. In vitro, the dye decolorization was markedly decreased by the absence of manganic ions and H2O2. These data suggest that manganese peroxidase appear to be the main responsible for the capability of L. edodes to decolorize synthetic dyes.
Bioresour Technol 2004 Sep
PMID:Decolorization of synthetic dyes by solid state cultures of Lentinula (Lentinus) edodes producing manganese peroxidase as the main ligninolytic enzyme. 1515 1

The decolorizing capacity of 26 white rot fungi from Argentina was investigated. Extracellular production of ligninolytic enzymes by mycelium growing on solid malt extract/glucose medium supplemented with different dyes (Malachite Green, Azure B, Poly R-478, Anthraquinone Blue, Congo Red and Xylidine), dye decolorization and the relationship between these two processes were studied. Only ten strains decolorized all the dyes, all ten strains produced laccase, lignin peroxidase and manganese peroxidase on solid medium. However, six of the strains could not decolorize any of the dyes; all six strains tested negative for lignin peroxidase, and produced less than 0.05 U/g agar of manganese peroxidase. Comparing the isolates with the well-known dye-degrader Phanerochaete chrysosporium, a new fungus was identified: Coriolus versicolor f. antarcticus, potentially a candidate for use in biodecoloration processes. Eighteen day-old cultures of this fungus were able to decolorize in an hour 28%, 30%, 43%, 88% and 98% of Xylidine (24 mg/l), Poly R-478 (75 mg/l), Remazol Brilliant Blue R (9 mg/l), Malachite Green (6 mg/l) and Indigo Carmine (23 mg/l), respectively. Laccase activity was 0.13 U/ml, but neither lignin peroxidase nor manganese peroxidase were detected in the extracellular fluids for that day of incubation.
Bioresour Technol 2004 Sep
PMID:Evaluation of Argentinean white rot fungi for their ability to produce lignin-modifying enzymes and decolorize industrial dyes. 1515 9

Laccases and other four-copper oxidases are usually constructed of three domains: Domains one and three house the copper sites, and the second domain often helps form a substrate-binding cleft. In contrast to this arrangement, the genome of Streptomyces coelicolor was found to encode a small, four-copper oxidase that lacks the second domain. This protein is representative of a new family of enzymes--the two-domain laccases. Disruption of the corresponding gene abrogates laccase activity in the growth media. We have recombinantly expressed this enzyme, called SLAC, in Escherichia coli and characterized it. The enzyme binds four copper ions/monomer, and UV-visible absorption and EPR measurements confirm that the conserved type 1 copper site and trinuclear cluster are intact. We also report the first known paramagnetic NMR spectrum for the trinuclear copper cluster of a protein from the laccase family. The enzyme is highly stable, retaining activity as a dimer in denaturing gels after boiling and SDS treatment. The activity of the enzyme against 2,6-dimethoxyphenol (DMP) peaks at an unprecedentedly high pH (9.4), whereas the activity against ferrocyanide decreases with pH. SLAC binds negatively charged substrates more tightly than positively charged or uncharged molecules.
Protein Sci 2004 Sep
PMID:Characterization of SLAC: a small laccase from Streptomyces coelicolor with unprecedented activity. 1529 17

The laccase from the fungus Coprinus cinereus has been prepared and crystallized in a form suitable for X-ray diffraction analysis. Small plate-like crystals of an enzymatically deglycosylated form of the enzyme have been grown by the hanging-drop method using polyethylene glycol as precipitant. These crystals diffract to at least 2.2 A. They belong to the space group P2(1)2(1)2(1) with cell dimensions a = 45.4, b = 85.7, c = 143.1 A with a single molecule of laccase in the asymmetric unit.
Acta Crystallogr D Biol Crystallogr 1997 Sep 01
PMID:Crystallization and preliminary X-ray analysis of the laccase from Coprinus cinereus. 1529 93

Laccases from various sources were tested, and laccase from Rigidoporus lignosus was found to be the most active towards syringaldazine and ABTS, which are typical substrates of this class of enzymes, and towards the phenols found in olive oil mill wastewaters. This laccase was covalently immobilised by carbodiimide chemistry, on a self-assembled monolayer of 3-mercaptopropionic acid deposited on a gold surface. A flow biosensor, using the monolayer of laccase as bioelement and a glassy carbon electrode as amperometric transduction system, was developed. Although the amount of the immobilised enzyme (about 140 ng/cm2 effective surface area) was tiny, the biosensor showed a sensitivity of 3 nA/microM when 1,4-hydroquinone was used as substrate, and a half-life of 35 days. The proposed device permits detection of phenols in aqueous solutions at concentrations in the low micromolar range, i.e. below European Community limits. The biosensor was successfully used to detect phenols in wastewaters from an olive oil mill after minimal sample preparation (incubation of the aqueous sample with sodium borohydride for a few minutes) to suppress the current due to oxidised compounds present in the wastewaters.
Biosens Bioelectron 2004 Sep 15
PMID:A high sensitivity amperometric biosensor using a monomolecular layer of laccase as biorecognition element. 1530 36

A laccase with a novel N-terminal sequence, a molecular mass of 63kDa, and inhibitory activity toward HIV-1 reverse transcriptase (IC(50)=9.5microM) was isolated from dried fruiting bodies of the monkey head mushroom Hericium erinaceum. A chromatographic procedure involving ion exchange chromatography on DEAE-cellulose, CM-cellulose, and Q-Sepharose and fast protein liquid chromatography-gel filtration on Superdex 75 was employed. The laccase was adsorbed on DEAE-cellulose and Q-Sepharose but unadsorbed on CM-cellulose. High activity of the enzyme was observed at pH 3-5 and at 50-80 degrees C. Its activity was completely abolished at pH 8 and 9 and after boiling for 10min. A temperature of 50 degrees C and a pH of 5.0 were optimal for its activity.
Biochem Biophys Res Commun 2004 Sep 10
PMID:A new laccase from dried fruiting bodies of the monkey head mushroom Hericium erinaceum. 1531 67


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