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)

Two different bands with laccase activity were obtained after nondenaturing PAGE of the culture filtrate of Pleurotus ostreatus. Immunoblot analysis revealed that antisera raised against laccase I were not reactive to laccase II. Laccase I, which exhibited faster mobility on nondenaturing polyacrylamide gel, was purified 42.9-fold with an overall yield of 10.8%. Gel filtration and SDS-PAGE revealed that laccase I is a single polypeptide with a molecular mass of approximately 64 kDa. Laccase I contained 12.5% carbohydrate by weight and 3.9 mol copper (mol protein)-1. The absorption spectrum of laccase I showed a type 1 signal at 605 nm and EPR spectra showed that the parameters of the type 1 and type 2 Cu signals were g parallel = 2.197 and A parallel = 0.009 cm-1, and g parallel = 2.263 and A parallel = 0.0176 cm-1, respectively. The data obtained from the pH profiles suggested that two ionization groups, whose pKa values were 5.60-5.70 and 6.70-6.85, may play an important role in the active site of laccase I as the ligand of copper metal. The optimal pH and temperature for the activity of laccase I were 6.0-6.5 and 30-35 degrees C, respectively. The enzyme had affinity for various lignin-related phenolic compounds: the Km values for ferulic acid and syringic acid were 48 and 89 microM, respectively. EPR spectroscopic study of the action of laccase I on 3,5-dimethoxy-5-hydroxyacetophenone indicated that this enzyme catalyses single electron transfer with the formation of the phenoxy radical as an intermediate.
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PMID:Single electron transfer by an extracellular laccase from the white-rot fungus Pleurotus ostreatus. 770 70

The gene lac-1, encoding the enzyme laccase, is the best characterized of a number of genes in the chestnut blight fungus, Cryphonectria parasitica, that are repressed by hypoviruses, a group of virulence-attenuating mycoviruses. lac-1 has also been shown to be transcriptionally activated by low concentrations of the translational inhibitor cycloheximide (CHX) and by the immunosuppressant cyclosporin A. We now report the identification of a CHX responsive element within the lac-1 promoter region. Gel-mobility shift analysis revealed a 111-bp fragment located 1.8kb upstream of the lac-1 transcriptional start point that exhibited protein binding activity. Insertion of this element within a basal lac-1 promoter sequence conferred CHX responsive transcriptional activation. Moreover, this activation was prevented by hypovirus infection. A 22-bp sequence with an imperfect dyad symmetry located within the 111-bp element was found to be essential for sequence-specific protein binding and, thus, represents a putative target for interactions between the lac-1 promoter and proteins that are involved in mediating CHX inducible activation of lac-1 transcription.
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PMID:Identification of a Cryphonectria parasitica laccase gene promoter element involved in cycloheximide-inducible, hypovirus-repressible transcriptional activation. 952 29

Phenolic and nonphenolic (permethylated) synthetic [14C]lignins were depolymerized by Trametes villosa laccase in the presence of a radical mediator, 1-hydroxybenzotriazole (HOBT). Gel permeation chromatography of the treated lignins showed that approximately 10% of their substructures were cleaved. The system also cleaved a beta-O-4-linked model compound, 1-(4-ethoxy-3-methoxy-ring-[14C]phenyl)-2-(2-methoxyphenoxy)-propane- 1,3-diol, and a beta-1-linked model, 1, 2-bis-(3-methoxy-4-[14C]methoxyphenyl)-propane-1,3-diol, that represent nonphenolic substructures in lignin. High performance liquid chromatography of products from the oxidized models showed that they were produced in sufficient yields to account for the ability of laccase/HOBT to depolymerize nonphenolic lignin.
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PMID:Degradation of nonphenolic lignin by the laccase/1-hydroxybenzotriazole system. 1098 77

The feasibility of laccase production by immobilization of Pleurotus ostreatus 1804 on polyurethane foam (PUF) cubes with respect to media composition was studied in both batch and reactor systems. Enhanced laccase yield was evidenced due to immobilization. A relatively high maximum laccase activity of 312.6 U was observed with immobilized mycelia in shake flasks compared to the maximum laccase activity of free mycelia (272.2 U). It is evident from this study that the culture conditions studied, i.e. biomass level, pH, substrate concentration, yeast extract concentration, Cu2+ concentration, and alcohol nature, showed significant influence on the laccase yield. Gel electrophoretic analysis showed the molecular weight of the laccase produced by immobilized P. ostreatus to be 66 kDa. The laccase yield was significantly higher and more rapid in the packed bed reactor than in the shake flask experiments. A maximum laccase yield of 392.9 U was observed within 144 h of the fermentation period with complete glucose depletion.
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PMID:Laccase production using Pleurotus ostreatus 1804 immobilized on PUF cubes in batch and packed bed reactors: influence of culture conditions. 1599 50

Microorganisms were screened from the natural environment for decolorization of molasses spent wash, and the isolated strains were then employed in the treatment of actual wastewater. The primary screening was carried out on agar plates supplemented with synthesized melanoidin as the target substrate, since melanoidin is one of the most refractory pigments in wastewater. Promising microorganisms were further selected through secondary screening by decolorization of untreated actual wastewater in shaking flask cultures. Gel filtration chromatography was used to determine the molecular weight distribution of pigments in molasses spent wash before and after decolorization. A strain named A5P1 was isolated from the soil samples collected, showing a good ability of decolorizing molasses spent wash, and was later identified as Aspergillus flavus by morphology and ITS sequence analysis. Experimental study of factors affecting the decolorization performance of strain A5P1 gave the optimal conditions as follows: 4.3 x 10(4) mL(-1) of inoculum size, medium with initial pH of 4.5 and cultivation at 39 degrees C. It could decolorize 53.0% of the pigments in the untreated molasses spent wash and decreased 80% of chemical oxygen demand after four-day incubation. The result of gel filtration chromatography demonstrated that both the large and small molecular weight fractions of pigments in the molasses spent wash could be removed by strain A5P1. Based on the measurement of enzyme activities, at least three different kinds of enzymes, i. e. the enzyme with H2O2-producing activity, laccase and manganese peroxidase were involved in the decolorization process. Therefore, the decolorization mechanism of strain A5P1 was preliminarily considered to be mainly biodegradation, with bioadsorption as a minor reaction.
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PMID:[Screening and identification of microorganisms for decolorization of molasses spent wash]. 2324 85

Although melanin is known for protecting living organisms from harmful physical and chemical factors, its synthesis is rarely observed among endospore-forming Bacillus cereus sensu lato. Here, for the first time, we reported that psychrotolerant Bacillus weihenstephanensis from Northeastern Poland can produce melanin-like pigment. We assessed physicochemical properties of the pigment and the mechanism of its synthesis in relation to B. weihenstephanensis genotypic and phenotypic characteristics. Electron paramagnetic resonance (EPR) spectroscopy displayed a stable free radical signal of the pigment from environmental isolates which are consistent with the commercial melanin. Fourier transform infrared spectroscopy (FT-IR) and physicochemical tests indicated the phenolic character of the pigment. Several biochemical tests showed that melanin-like pigment synthesis by B. weihenstephanensis was associated with laccase activity. The presence of the gene encoding laccase was confirmed by the next generation whole genome sequencing of one B. weihenstephanensis strain. Biochemical (API 20E and 50CHB tests) and genetic (Multi-locus Sequence Typing, 16S rRNA sequencing, and Pulsed-Field Gel Electrophoresis) characterization of the isolates revealed their close relation to the psychrotrophic B. weihenstephanensis DSMZ 11821 reference strain. The ability to synthesize melanin-like pigment by soil B. weihenstephanensis isolates and their psychrotrophic character seemed to be a local adaptation to a specific niche. Detailed genetic and biochemical analyses of melanin-positive environmental B. weihenstephanensis strains shed some light on the evolution and ecological adaptation of these bacteria. Moreover, our study raised new biotechnological possibilities for the use of water-soluble melanin-like pigment naturally produced by B. weihenstephanensis as an alternative to commercial non-soluble pigment.
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PMID:Melanin-Like Pigment Synthesis by Soil Bacillus weihenstephanensis Isolates from Northeastern Poland. 2590 51

This paper demonstrates the presence of an active laccase-like enzyme from deepwater pink shrimp (Parapenaeus longirostris) using polyacrylamide gel electrophoresis. This enzyme was found in all anatomical parts of the deepwater pink shrimp, but particularly in the cephalothorax, and became active during the course of storage. Gel staining with laccase-specific substrates such as ADA, DMP and DAB was used to characterize a protein of around 44kDa as containing laccase activity. The enzyme was inhibited by a specific inhibitor, CTAB. 4-Hexylresorcinol, a specific inhibitor of polyphenoloxidase (PPO), did not inhibit the laccase-like enzyme. Low concentrations of antioxidants ascorbic acid or sodium metabisulphite were sufficient to inhibit the laccase-like enzyme. ABTS and DMP were subsequently used to characterize the enzyme. Given the evidence of this enzyme in deepwater pink shrimp, new melanosis-inhibiting compounds that are suitable for consumption need to be found to complement specific inhibitors of PPO activity.
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PMID:Evidence of an active laccase-like enzyme in deepwater pink shrimp (Parapenaeus longirostris). 2605 41