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:1.11.1.7 (peroxidase)
65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In an investigation of the role of peroxidase enzymes in the differentiation of the tissues of the crease region of barley, plants of winter barley cv. Halcyon were grown from anthesis onwards in controlled conditions at a constant temperature of 16 degrees C. Four ears were harvested at 2-d intervals from 6 d after anthesis (daa) until 50 daa. Grains from mid-ear were used for (i) fresh and dry weight determinations, (ii) extraction of crease tissue for the determination of peroxidase activity and for the separation of isozymes of peroxidase by isoelectric focusing (IEF) and (iii) detection of lignin and suberin in the tissues of the crease using autofluorescence and cytochemistry. Peroxidase activity was located histochemically in the crease tissue of cv. Chariot. Scanning electron microscopy studies were carried out on developing grains of cv. Blenheim. Maximum grain water content was achieved at 14 daa. Lignin and suberin were detected in the walls of the chalazal cells from 18 daa onwards. No changes in the staining of chalazal cell walls were detected at the end of grain filling (32 daa), but loss of autofluorescence and staining were observed at 42 daa, just prior to the final, rapid phase of grain dehydration. Peroxidase activity per fresh weight of crease tissue was high at 6 daa and low at 22 daa. It was also low between 32 and 40 daa, but it rose again from 42 daa onwards. IEF demonstrated that both anionic and cationic isozymes of peroxidase were present in crease tissue, the pattern of bands showing some marked changes during the course of grain development.
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PMID:Changes in chalazal cell walls and in the peroxidase enzymes of the crease region during grain development in barley. 1093 7

Lignin-degrading manganese (II) peroxidase (MnP) purified from the culture of a wood-rotting basidiomycete, Bjerkandera adusta, was used in the polymerization of guaiacol. MnP was found to catalyze polymerization of guaiacol in 50% aqueous acetone, dimethyl formamide, methanol, ethanol, dioxane, acetonitrile, ethylene glycol and methylcellosolve. Maximum yield of polyguaiacol was achieved in 50% aqueous acetone. The weight average molecular weight (Mw) of the polymer was estimated to be 30,300 by gel permeation chromatography. However, matrix-assisted laser desorption ionization time of flight mass spectroscopy (MALDI-TOF-MS) analysis gave a more reliable Mw of 1,690. IR, 13C-NMR, MALDI-TOF-MS and pyrolysis GC-MS analyses showed the presence of C-C and C-O linkages and quinone structure in polyguaiacol. It was also indicated that polyguaiacol has a methoxy-phenyl group as the terminal moiety. This suggests that polyguaiacol is a branched polymer in which guaiacol units are cross-linked at the phenolic group. Thermal gravimetric and differential scanning calorimetric analyses were also carried out. MnP also catalyzed the polymerization of o-cresol, 2,6-dimethoxyphenol and other phenolic compounds and aromatic amines. Mw of these polymers ranged from around 1,000 to 1,500.
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PMID:Polymerization of guaiacol by lignin-degrading manganese peroxidase from Bjerkandera adusta in aqueous organic solvents. 1095 12

White rot fungi were collected from Chirinda and Chimanimani hardwood forests in Zimbabwe and studied with respect to growth temperature optima and dye decolorization. Temperature optima were found to vary (between 25-37 degrees C) amongst the isolates. The isolates were screened for their ability to degrade the polymeric dyes; blue dextran and Poly R478 and the triphenylmethane dyes; cresol red, crystal violet and bromophenol blue. Semi-quantitative determination of the hydrolytic enzyme activities possessed by the white rot fungi was determined using the API ZYM system. Lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase activities in the fungi were also determined. No LiP was detected in any of the isolates but all isolates showed manganese peroxidase and laccase activities. Time related decolorization studies and optimum pH determinations for Poly R478 degradation by the isolates were carried out in liquid cultures. The most significant rates of Poly R478 decolorization in liquid cultures were found with the following isolates: Trametes cingulata, Trametes versicolor, Trametes pocas, DSPM95 (a species to be identified), Datronia concentrica and Pycnoporus sanguineus.
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PMID:Growth, dye degradation and ligninolytic activity studies on Zimbabwean white rot fungi. 1124 Feb 1

Extracellular manganese peroxidase (MnP) was purified from the compost extract of Agaricus bisporus using anion exchange chromatography, gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Two forms (MnP1 and MnP2) were separated by isoelectric focusing and their isoelectric points were determined to be 3.25 (MnP1) and 3.3 (MnP2). Both forms had a molecular mass of 40 kDa. The first 25 amino acids of the N-terminal end of MnP1 sequence was found to share 68% identity with a Pleurotus ostreatus and a P. eryngii MnP. Lignin peroxidase was not detected during any of the steps in the purification process. In liquid cultures with both soluble and insoluble carbon sources in defined medium (D-glucose, glycerol, Whatman CC-41 microcrystalline cellulose or Solka-floc cellulose) MnP protein was detected in culture fluid by Western blot, but no MnP activity could be detected. A. bisporus appears to be in the group of ligninolytic fungi which do not produce lignin peroxidase.
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PMID:Characteristics and N-terminal amino acid sequence of manganese peroxidase from solid substrate cultures of Agaricus bisporus. 1133 Jul 10

Lignin peroxidase (LiP) plays a central role in the biodegradation of the plant cell wall constituent lignin. LiP is able to oxidize aromatic compounds with redox potentials higher than 1.4 V (NHE) by single electron abstraction, but the exact redox mechanism is still poorly understood. The finding in our laboratory that the Cbeta-atom of Trp171 carries a unique modification led us to initiate experiments to investigate the role of this residue. These experiments, employing crystallography, site-directed mutagenesis, protein chemistry, spin-trapping and spectroscopy, yielded the following results: (i) Trp171 is stereospecifically hydroxylated at its Cbeta-atom as the result of an auto-catalytic process, which occurs under turnover conditions in the presence of hydrogen peroxide. (ii) Evidence for the formation of a Trp171 radical intermediate has been obtained using spin-trapping, in combination with peptide mapping and protein crystallography. (iii) Trp171 is very likely to be involved in electron transfer from natural substrates to the haem cofactor via LRET. (iv) Mutagenetic substitution of Trp171 abolishes completely the oxidation activity for veratryl alcohol, but not for artificial substrates. (v) Structural changes in response to the mutation are marginal. Therefore the lack of activity is due to the absence of the redox active indole side chain.
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PMID:Lignin peroxidase structure and function. 1135 37

Lignin peroxidase (LiP) and manganese peroxidase (MnP) have been investigated in Phanerochaete chrysosporium. A third ligninolytic peroxidase has been described in Pleurotus and Bjerkandera. Two of these versatile peroxidases (VPs) have been cloned, sequenced and characterized. They have high affinity for Mn(2+), hydroquinones and dyes, and also oxidize veratryl alcohol, dimethoxybenzene and lignin dimers. The deduced sequences show higher identity with Ph. chrysosporium LiP than MnP, but the molecular models obtained include a Mn(2+)-binding site. Concerning aromatic substrate oxidation, Pl. eryngii VP shows a putative long-range electron transfer pathway from an exposed trytophan to haem. Mutagenesis and chemical modification of this tryptophan and the acidic residues forming the Mn(2+)-binding site confirmed their role in catalysis. The existence of several substrate oxidation sites is supported further by biochemical evidence. Residue conservation in other fungal peroxidases is discussed.
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PMID:A new versatile peroxidase from Pleurotus. 1135 38

Lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase activities in selected sub-tropical white rot fungal species from Zimbabwe were determined. The enzyme activities were assayed at varying concentrations of C, N and Mn2+. Manganese peroxidase and laccase activities were the only expressed activities in the fungi under the culture conditions tested. Trametes species, T. cingulata, T. elegans and T. pocas produced the highest manganese peroxidase activities in a medium containing high carbon and low nitrogen conditions. High nitrogen conditions favoured high manganese peroxidase activity in DSPM95, L. velutinus and Irpex spp. High manganese peroxidase activity was notable for T. versicolor when both carbon and nitrogen in the medium were present at high levels. Laccase production by the isolates was highest under conditions of high nitrogen and those conditions with both nitrogen and carbon at high concentration. Mn2+ concentrations between 11-25 ppm gave the highest manganese peroxidase activity compared to a concentration of 40 ppm or when there was no Mn2+ added. Laccase activity was less influenced by Mn2+ levels. While some laccase activity was produced in the absence of Mn2+, the enzyme levels were higher when Mn2+ was added to the culture medium.
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PMID:Ligninolytic enzyme production in selected sub-tropical white rot fungi under different culture conditions. 1144 59

Lignin peroxidase shares several structural features with the well-studied horseradish peroxidase and cytochrome c peroxidase but carries a higher redox potential. Here the heme domain of lignin peroxidase and the lignin peroxidase cyanide adduct was examined by 1HNMR spectroscopy, including nuclear Overhauser effect and two-dimensional measurements, and the findings were compared with those for horseradish peroxidase and cytochrome c peroxidase. Structural information was obtained on the orientation of the heme vinyl and propionate groups and the proximal and distal histidines. The shifts of the epsilon1 proton of the proximal histidine were found to be empirically related to the Fe3+/Fe2+ redox potentials.
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PMID:Proton NMR investigation into the basis for the relatively high redox potential of lignin peroxidase. 1160 6

Three strains of the white-rot fungus Panus tigrinus (FTPT-4741, FTPT-4742, and FTPT-4745) were cultivated on sugarcane bagasse prior to kraft pulping. Pulp yields, kappa number, and viscosity of all pulps were determined and Fourier transform infrared (FTIR) spectra from the samples were recorded. The growth of P. tigrinus strains in plastic bags increased the manganese peroxide and xylanase activities. Lignin peroxidase was not detected in the three systems (shaken and nonshaken flasks and plastic bags). FTIR spectra were reduced to their principal components, and a clear separation between FTPT-4742 and the control was observed. Strain FTPT-4745 decayed lignin more selectively in the three systems utilized. Yields of kraft pulping were low, ranging from 20 to 45% for the plastic bag samples and from 12 to 38% for the flask samples. Kappa numbers were 1-18 and viscosity ranged from 2.3 to 6.8 cP.
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PMID:Panus tigrinus strains used in delignification of sugarcane bagasse prior to kraft pulping. 1201 65

Lignin is one of the most abundant biopolymers, and it has a complex racemic structure. It may be formed by a radical polymerization initiated by redox enzymes, but much remains unknown about the process, such as how molecules as large as enzymes can generate the compact structure of the lignified plant cell wall. We have synthesized lignin oligomers according to a new concept, in which peroxidase is never in direct contact with the lignin monomers coniferaldehyde and coniferyl alcohol. Instead, manganese oxalate worked as a diffusible redox shuttle, first being oxidized from Mn(II) to Mn(III) by a peroxidase and then being reduced to Mn(II) by a simultaneous oxidation of the lignin monomers to radicals that formed covalent linkages of the lignin type. Furthermore, a high molecular mass polymer was generated by oxidation of coniferyl alcohol by Mn(III) acetate in a dioxane and water mixture. This polymer was very similar to natural spruce wood lignin, according to its NMR spectrum. The possible involvement of a redox shuttle/peroxidase system in lignin biosynthesis is discussed.
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PMID:Polymerization of monolignols by redox shuttle-mediated enzymatic oxidation: a new model in lignin biosynthesis I. 1217 33


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