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)

(sup14)C-synthetic lignin mineralization by the basidiomycete Ceriporiopsis subvermispora occurs at the highest rate (about 30% after 29 days) in liquid cultures containing 1% glucose and a growth-limiting amount (1 mM) of ammonium tartrate. The titers of manganese peroxidase (MnP) and laccase are lower in these cultures than in cultures containing 1% glucose and 10 mM ammonium tartrate, where the extent of lignin mineralization in the same period is only about 15%. The inverse correlation between enzyme activity and lignin mineralization is also observed when ammonium tartrate is replaced by ammonium chloride or Casamino Acids as the source of nitrogen. This phenomenon can be explained by a gradual increase in the pH of the medium that takes place only in the cultures with high nitrogen concentrations. Supporting this finding, when cultures with 1 mM ammonium tartrate were grown at different pHs, (sup14)CO(inf2) evolved more rapidly from those with pH values near the optimum for MnP activity. On the other hand, (sup14)CO(inf2) evolution from cultures containing 1% glucose supplemented with 1 mM ammonium tartrate plus 9 mM sodium tartrate was as low as that from cultures with a high ammonium tartrate concentration. Since the changes in the pH of these cultures were not as pronounced as those in cultures containing high nitrogen concentrations, tartrate itself may also be contributing to limit the extent of lignin mineralization. Considering that pH instability seems to constitute a common feature of fungal cultures, precautions must be taken to avoid underestimation of their ligninolytic efficiencies.
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PMID:Synthetic Lignin Mineralization by Ceriporiopsis subvermispora Is Inhibited by an Increase in the pH of the Cultures Resulting from Fungal Growth. 1653 66

A novel marine melanogenic bacterium, strain MMB-1, was isolated from the Mediterranean Sea. The taxonomic characterization of this strain indicated that it belongs to the genus Alteromonas. Under in vivo conditions, L-tyrosine was the specific monophenolic precursor for melanin synthesis. This bacterium contained all types of activities associated with polyphenol oxidases (PPOs), cresolase (EC 1.18.14.1), catecholase (EC 1.10.3.1), and laccase (EC 1.10.3.2). These activities were due to the presence of two different PPOs. The first one showed all the enzymatic activities, but it was not involved in melanogenesis in vivo, since amelanogenic mutant strains obtained by nitrosoguanidine treatment contained levels of this PPO similar to that of the wild-type MMB-1 strain. The second PPO showed cresolase and catecholase activities but no laccase, and it was involved in melanogenesis, since this enzyme was lost in amelanogenic mutant strains. This PPO was strongly activated by sodium dodecyl sulfate below the critical micelle concentration, and it is a tyrosinase-like enzyme showing a lag period in its tyrosine hydroxylase activity that could be avoided by small amounts of L-dopa. This is the first report of a bacterium that contains two PPOs and also the first report of a pluripotent PPO showing all types of oxidase activities. The bacterium and the pluripotent PPO may be useful models for exploring the roles of PPOs in cellular physiology, aside from melanin formation. On the other hand, the high oxidizing capacity of the PPO for a wide range of substrates could make possible its application in phenolic biotransformations, food processing, or the cosmetic industry, where fungal and plant PPOs are being used.
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PMID:Isolation and Characterization of Strain MMB-1 (CECT 4803), a Novel Melanogenic Marine Bacterium. 1653 88

Continuous gradient elution chromatography (CGEC) was employed to purify and separate enzymes and polysaccharides from the sap of Rhus vernicifera Chinese lacquer tree. There are three different molecules with laccase enzyme activity. Two are enzymes of each other (L1, and L2), whereas the third (RL) is an entirely separate entity. Two polysaccharides (GP1 and GP2) were also found. The Rhus laccase (RL), and isoenzymes L1 and L2, have peak molecular masses of 109,100, 120,000, 103,000 respectively; each has four copper atoms per molecule, and the pI values were 8.2, 8.6, and 9.1, respectively. The structure of the laccases was studied by Fourier-transform infrared (FT-IR) and Matrix-assisted laser desorption/ionization time-of flight (MALDI-TOF) mass spectrometry. The typical amide I (1646cm(-1)) and amide II (1545cm(-1)) bands were observed. The results from MALDI-TOF were similar to those from CGEC, but the molecular mass from the MALDI-TOF was significantly different from that obtained from sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).
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PMID:Purification and characterization of hydrosoluble components from the sap of Chinese lacquer tree Rhus vernicifera. 1658 Jul 25

Thin-layer spectroelectrochemical methods have been employed to measure the reduction potentials of the blue copper in Polyporus versicolor laccase (EC 1.10.3.2) between 7 degrees C and 41 degrees C (0.2 M sodium phosphate, pH 5.4). Thermodynamic parameters are: DeltaS degrees = -13.9 +/- 2 cal/mol-K; DeltaH degrees = -22.1 +/- 0.5 kcal/mol; E degrees (25 degrees C) = 780 +/- 3 mV vs. the normal hydrogen electrode. Comparison of the DeltaS degrees and DeltaH degrees values with those for single-site proteins suggests that the high potential of the blue copper in fungal laccase is attributable mainly to stabilization of the copper (I) center by enhanced ligand binding interactions and that protein solvation effects play a lesser role.
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PMID:Temperature dependence of the reduction potential of blue copper in fungal laccase. 1659 93

Current understanding of the final oxidative steps leading to lignin deposition in trees and other higher plants is limited with respect to what enzymes are involved, where they are localized, how they are transported, and what factors regulate them. With the use of cell suspension cultures of sycamore maple (Acer pseudoplatanus), an in-depth study of laccase, one of the oxidative enzymes possibly responsible for catalyzing the dehydrogenative polymerization of monolignols in the extracellular matrix, was undertaken. The time course for secretion of laccase into suspension culture medium was determined with respect to age and mass of the cells. Laccase was completely separated from peroxidase activity by hydrophobic interaction column chromatography, and its purity was assessed with different types of gel electrophoresis (isoelectric focusing-, native-, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Amino acid and glycosyl analyses of the purified enzyme were compared with those reported from previous studies of plant and fungal laccases. The specific activity of laccase toward several common substrates, including monolignols, was determined. Unlike a laccase purified from the Japanese lacquer tree (Rhus vernicifera), laccase from sycamore maple oxidized sinapyl, coniferyl, and p-coumaryl alcohols to form water-insoluble polymers (dehydrogenation polymers).
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PMID:Laccase from Sycamore Maple (Acer pseudoplatanus) Polymerizes Monolignols. 1666 84

Polyphenol oxidase activity (PPO, EC 1.14.18.1, monophenol monooxygenase, and EC 1.10.3.2, o-diphenoloxidase) has been extensively studied in banana fruit for its role in enzymatic browning. Rapid discolouration of leaf, stem and root tissue after injury and strong pigmentation of tissue extracts indicate that PPO and phenolic compounds are ubiquitous in vegetative tissue of banana as well. They hamper biochemical and molecular studies in banana, as cumbersome adaptations of extraction protocols are required. On the other hand, PPO and phenolic compounds could be an important part of the plant's defence system against pests and diseases, including root parasitic nematodes. To facilitate future studies in this area, extraction and assay conditions for PPO from roots of banana (Musa acuminata AAA, Grande naine) were optimized. Highest enzyme activities were obtained in a 0.2 M phosphate buffer at pH 7.0 with 5% insoluble polyvinylpyrrolidone and 0.25% Triton X-100. The lowest K(m) values were obtained for dopamine and D-catechin. Monophenolase activity was shown with p-cresol. Banana root PPO was strongly inhibited by dithiothreitol and sodium metabisulfite. In root sections, oxidation of dopamine strongly co-localized with aerenchyma in the cortex. The experiments revealed indications for the involvement of root PPO and dopamine in resistance of banana against the parasitic nematode Radopholus similis.
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PMID:Extraction and partial characterization of polyphenol oxidase from banana (Musa acuminata Grande naine) roots. 1681 56

The rhg1 gene or genes lie at a recessive or co-dominant locus, necessary for resistance to all Hg types of the soybean (Glycine max (L.) Merr.) cyst nematode (Heterodera glycines I.). The aim here was to identify nucleotide changes within a candidate gene found at the rhg1 locus that were capable of altering resistance to Hg types 0 (race 3). A 1.5 +/- 0.25 cM region of chromosome 18 (linkage group G) was shown to encompass rhg1 using recombination events from four near isogenic line populations and nine DNA markers. The DNA markers anchored two bacterial artificial chromosome (BAC) clones 21d9 and 73p6. A single receptor like kinase (RLK; leucine rich repeat-transmembrane-protein kinase) candidate resistance gene was amplified from both BACs using redundant primers. The DNA sequence showed nine alleles of the RLK at Rhg1 in the soybean germplasm. Markers designed to detect alleles showed perfect association between allele 1 and resistance to soybean cyst nematode Hg types 0 in three segregating populations, fifteen additional selected recombination events and twenty-two Plant Introductions. A quantitative trait nucleotide (QTN) [corrected] in the RLK at rhg1 was inferred that alters A87 to V87 in the context of H274 rather than N274. [corrected] Contiguous DNA sequence of 315 kbp of chromosome 18 (about 2 cM) contained additional gene candidates that may modulate resistance to other Hg-types including a variant laccase, a hydrogen-sodium ion antiport and two proteins of unknown function. A molecular basis for recessive and co-dominant resistance that involves interactions among paralagous disease-resistance genes was inferred that would improve methods for developing new nematode-resistant soybean cultivars.
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PMID:Genomic analysis of the rhg1 locus: candidate genes that underlie soybean resistance to the cyst nematode. 1702 28

The white rot fungus Pycnoporus sanguineus produced high amount of laccase in the basal liquid medium without induction. Laccase was purified using ultrafiltration, anion-exchange chromatography, and gel filtration. The molecular weight of the purified laccase was estimated as 61.4 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme oxidized typical substrates of laccases including 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate), 2,6-dimethoxyphenol, and syringaldazine. The optimum pH and temperature for the purified laccase were 3.0 and 65 degrees C, respectively. The enzyme was stable up to 40 degrees C, and high laccase activity was maintained at pH 2.0-5.0. Sodium azide, L-cysteine, and dithiothreitol strongly inhibited the laccase activity. The purified enzyme efficiently decolorized Remazol Brilliant Blue R in the absence of added redox mediators. The high production of P. sanguineus laccase as well as its decolorization ability demonstrated its potential applications in dye decolorization.
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PMID:Purification and characterization of laccase from Pycnoporus sanguineus and decolorization of an anthraquinone dye by the enzyme. 1718 37

'Large' and 'small' fractions of laccase were found in the thalli of lichens Solorina crocea and Peltigera aphthosa. In both lichens, 'large', possibly dimeric, laccases were determined as 175 and 165 kDa (based on the gel filtration data), and 'small' ones were 76 and 97 kDa (according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis data), respectively. By their substrate specificity, pH optima, and thermostability, they were typical laccases. The fractions of 'small' laccases of 45 kDa from S. crocea and 55 kDa from P. aphthosa consisted of two enzymes.
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PMID:Laccases produced by lichens of the order Peltigerales. 1768 Oct 9

Response surface methodology (RSM) was successfully applied to enzymatic bio-transformation of 1-naphthol. The experiments were conducted in a closed system containing acetone and sodium acetate buffer, with laccase enzyme. Laccase enzyme used as catalyst was derived from Trametes versicolor (ATCC 200801). The enzymatic bio-transformation rate of 1-naphthol, based on measurements of initial dissolved oxygen (DO) consumption rate in the closed system, was optimized by the application of RSM. The independent variables, which had been found as the most effective variables on the initial DO consumption rate by screening experiments, were determined as medium temperature, pH and acetone content. A quadratic model was developed through RSM in terms of related independent variables to describe the DO consumption rate as the response. Based on contour plots and variance analysis, optimum operational conditions for maximizing initial DO consumption rate, while keeping acetone content at its minimum value, were 301 K of temperature, pH 6 and acetone content of 7% to obtain 9.17 x 10(-3) mM DO/min for initial oxidation rate.
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PMID:An approach for prediction of optimum reaction conditions for laccase-catalyzed bio-transformation of 1-naphthol by response surface methodology (RSM). 1805 8


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