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)

Dibenzo-p-dioxin (I) was rapidly degraded in ligninolytic cultures of the basidiomycete Phanerochaete chrysosporium. Lignin peroxidase (LiP) oxidized I to generate the following products: catechol (V), dibenzo-p-dioxin-2,3-quinone (VIII), 2-hydroxy-5-(2-hydroxyphenoxy)-1,4-benzoquinone (IX), 4,5-dihydroxy-1,2-benzoquinone (X), 2-(2-hydroxyphenoxy)-1,4-benzoquinone (XI), 4-hydroxy-1,2-benzoquinone (XII), and 1,2-benzoquinone (XIII). Identical products were formed when the reaction was conducted under argon. No incorporation of 18O into products was observed when the reaction was conducted under 18O2. Oxidation of I in H(2)18O resulted in incorporation of two atoms of 18O into the quinone VIII. Nonenzymatic hydrolysis of the quinone (VIII) yielded catechol (V), IX and X. Hydrolysis of VIII in H(2)18O resulted in incorporation of 18O atoms into IX and X, whereas no incorporation of 18O atoms into V was observed. These results are explained by mechanisms involving the one-electron oxidation of I by LiP to produce the corresponding cation radical. Nucleophilic attack of water on the cation radical generates a 2-hydroxydibenzo-p-dioxin radical, which is oxidized to a delocalized cation. The attack of water at position C-4a of the 2-hydroxydibenzo-p-dioxin cation, followed by oxidation and C-O-C bond cleavage, lead to formation of the quinone (XI), which undergoes 1,4-addition of water and cleavage of the second C-O-C bond to generate V and XII.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Oxidation of dibenzo-p-dioxin by lignin peroxidase from the basidiomycete Phanerochaete chrysosporium. 808 14

The ligninolytic enzymes produced by the white rot fungus Phanerochaete sordida in liquid culture were studied. Only manganese peroxidase (MnP) activity could be detected in the supernatant liquid of the cultures. Lignin peroxidase (LiP) and laccase activities were not detected under a variety of different culture conditions. The highest MnP activity levels were obtained in nitrogen-limited cultures grown under an oxygen atmosphere. The enzyme was induced by Mn(II). The initial pH of the culture medium did not significantly affect the MnP production. Three MnP isozymes were identified (MnPI, MnPII, and MnPIII) and purified to homogeneity by anion-exchange chromatography followed by hydrophobic chromatography. The isozymes are glycoproteins with approximately the same molecular mass (around 45 kDa) but have different pIs. The pIs are 5.3, 4.2, and 3.3 for MnPI, MnPII, and MnPIII, respectively. The three isozymes are active in the same range of pHs (pHs 3.0 to 6.0) and have optimal pHs between 4.5 and 5.0. Their amino-terminal sequences, although highly similar, were distinct, suggesting that each is the product of a separate gene.
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PMID:Manganese peroxidases of the white rot fungus Phanerochaete sordida. 813 19

Manganese peroxidase from the white rot basidiomycete Phanerochaete chrysosporium has been crystallized in a form suitable for high-resolution X-ray structure determination. Crystals were grown from solutions containing 30% polyethylene glycol 8000, ammonium sulfate and cacodylate buffer at pH 6.5, using macroseeding techniques. A complete data set has been obtained to 2.06 A resolution. The data can be indexed in space group P1 with a = 45.96 A, b = 53.77 A, c = 84.87 A, alpha = 97.01 degrees, beta = 105.72 degrees and gamma = 90.1 degrees, with two peroxidase molecules per asymmetric unit, or in space group C2 with a = 163.23 A, b = 45.97 A, c = 53.72 A and beta = 97.16 degrees, with only one molecule in the assymetric unit. Lignin peroxidase, which shares about 57% sequence identity with manganese peroxidase, was used as a probe for molecular replacement. Unique rotation and translation solutions have been obtained in space groups P1 and C2. The structure has been partially refined in space group C2 to R = 0.22 for data between 10 and 2.06 A.
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PMID:Preliminary crystallographic analysis of manganese peroxidase from Phanerochaete chrysosporium. 818 52

The potential commercial application of Phanerochaete chrysosporium requires methods for quantitatively predicting growth and substrate utilization. The growth kinetics of P. chrysosporium INA-12 (CNCM I-398) were investigated and modelled under nonlimiting nitrogen and carbon conditions in submerged static culture. This strain, unlike other strains, does not require nutrient limitation for induction of lignin peroxidase. Maximum levels of lignin peroxidase activity were reached 7 days after culture initiation, when almost 80% of the initial glycerol and 70% of the initial nitrogen were still present. Lignin peroxidase levels then decreased, while biomass levels increased until about day 14. The ratio of cell dry weight to wet weight was constant until the maximum biomass concentration was achieved, after which there was a decrease in the water content. The change in this ratio reflects cell lysis as it correlated with increased concentrations of nitrogen in the media, arising from cell leakage. The suitability of four growth models to predict growth, and in some cases glycerol consumption, was evaluated. A simple linear model and the Emerson model performed poorly for the early stages of growth, while a modified Williams model and the Monod model predicted substrate and biomass concentrations equally well. All models will predict biomass concentrations during the active growth phase, but they should not be used to predict biomass concentrations after the stationary growth phase, when cell lysis becomes significant.
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PMID:Modelling the growth kinetics of Phanerochaete chrysosporium in submerged static culture. 832 5

The ligninolytic enzymes synthesized by Phanerochaete chrysosporium BKM-F-1767 immobilized on polyurethane foam were characterized under limiting, sufficient, and excess nutrient conditions. The fungus was grown in a nonimmersed liquid culture system under conditions close to those occurring in nature, with nitrogen concentrations ranging from 2.4 to 60 mM. This nonimmersed liquid culture system consisted of fungal mycelium immobilized on porous pieces of polyurethane foam saturated with liquid medium and highly exposed to gaseous oxygen. Lignin peroxidase (LIP) activity decreased to almost undetectable levels as the initial NH4+ levels were increased over the range from 2.4 to 14 mM and then increased with additional increases in initial NH4+ concentration. At 45 mM NH4+, LIP was overproduced, reaching levels of 800 U/liter. In addition, almost simultaneous secretion of LIP and secretion of manganese-dependent lignin peroxidase were observed on the third day of incubation. Manganese-dependent lignin peroxidase activity was maximal under nitrogen limitation conditions (2.4 mM NH4+) and then decreased to 40 to 50% of the maximal level in the presence of sufficient or excess initial NH4+ concentrations. Overproduction of LIP in the presence of a sufficient nitrogen level (24 mM NH4+) and excess nitrogen levels (45 to 60 mM NH4+) seemed to occur as a response to carbon starvation after rapid glucose depletion. The NH4+ in the extracellular fluid reappeared as soon as glucose was depleted, and an almost complete loss of CO2 was observed, suggesting that an alternative energy source was generated by self-proteolysis of cell proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Overproduction of lignin peroxidase by Phanerochaete chrysosporium (BKM-F-1767) under nonlimiting nutrient conditions. 832 7

Lignin peroxidase immobilization was achieved by covalent coupling on CNBr-Sepharose 4B. Protein immobilization yield was around 80%. For veratryl alcohol oxidation, in the presence of hydrogen peroxide, both soluble and bound enzymes exhibited the same pH profile with an optimum near 2.5. Catalytic parameters (kc and Km) were seriously affected by immobilization. On the other hand, immobilization provided a noticeable stabilization of the enzyme against acidic pH and high temperatures. A 15-20 increase in the half-inactivation times at pH 2.2 and 2.7, respectively, could be observed. Bound enzyme was also much more thermostable than soluble.
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PMID:Immobilization as a tool for the stabilization of lignin peroxidase produced by Phanerochaete chrysosporium INA-12. 834 5

Electrophoretic karyotyping of the two most widely studied strains of Phanerochaete chrysosporium, BKMF-1767 and ME-446, has been determined using transverse alternating field electrophoresis. The genomic DNA of BKMF-1767 was resolved into 10 chromosomes ranging in size from 1.8-5.0 Mb, amounting to a total genome size of about 29 Mb. The genomic DNA of strain ME-446, on the other hand, was resolved into 11 chromosomes, amounting to a total genome size of about 32 Mb. Lignin peroxidase genes have been localized to five chromosomes in strain BKMF-1767 and to four chromosomes in strain ME-446.
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PMID:Electrophoretic karyotyping of the lignin-degrading basidiomycete Phanerochaete chrysosporium. 835 7

Lignin peroxidase H2 (LiPH2) from the white rot fungus Phanerochaete chrysosporium catalyzed the reduction of cytochrome c, nitro blue tetrazolium, ferric iron, molecular oxygen, and triiodide in a reaction mixture containing LiPH2, H2O2, EDTA, and iodide. Activity followed first order kinetics with respect to EDTA concentration. The reductive activity observed with LiPH2 using iodide as the mediator was comparable to that obtained using a variety of other free radical mediators such as veratryl alcohol, 1,4-dimethoxybenzene, and 1,2,3- and 1,2,4-trimethoxybenzene. EDTA-derived radicals were detected by ESR spin trapping upon incubation of LiPH2 with H2O2, iodide, and EDTA. Reduction activity was also observed using other peroxidases such as lactoperoxidase, horseradish peroxidase, and myeloperoxidase. For the reduction activity of LiPH2, it is proposed that the oxidation of EDTA is mediated by the iodide radical, and the reduction of various electron acceptors is mediated by EDTA radicals. The inhibition of reduction activity at higher concentrations of iodide might be due to the combination of iodide radicals to form I2 which forms a stable triiodide complex by reacting with excess iodide.
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PMID:Iodide as the mediator for the reductive reactions of peroxidases. 838 62

The basidiomycete Trametes versicolor, a white-rot fungus and potent degrader of lignin, produces multiple forms of extracellular peroxidases. Nine of these forms, six lignin peroxidases and three manganese(II) peroxidases, purified as described in the preceding paper, were characterized by amino-terminal sequencing, amino acid analyses, carbohydrate analyses, or peptide mapping. For two of the lignin peroxidase forms, tryptic peptides were isolated and sequenced to an extent corresponding to about 40 and 30%, respectively, of the primary structure. Eight of the nine peroxidases investigated were found to possess unique amino-terminal regions. A comparison of the sequences shows 57% of the residues to be identical, indicating a common ancestry for the lignin peroxidase and the manganese(II) peroxidase. The degree of identity among the five lignin peroxidases is about 80% and among the three manganese(II) peroxidases about 70%. Pairwise comparisons of the sequences disclosed that some of the lignin peroxidases are very closely related, either identical or differing only in a single amino acid residue of the thirty-five investigated. These close relationships are also supported by peptide mapping and by similarities in amino acid compositions. Tyr is absent in all isozymes. Lignin and manganese(II) peroxidases showed the presence of glucosamine and mannose in an amount corresponding to 3 to 6% of the molecular mass of the proteins. The carbohydrate compositions are compatible with the presence of 1, 2, and 3 sites of N-glycosylation. The results obtained strongly suggest that the complexity in the peroxidase pattern displayed by the fungus (T. Johansson and P.O. Nyman, Arch. Biochem. Biophys. 300, 49-56, 1993) can largely be accounted for by a heterogeneity at the gene level, probably in the form of multiple structural genes. Two recently published genes from genomic clones of T. versicolor are identical in sequence to two of the lignin peroxidases characterized here.
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PMID:Isozymes of lignin peroxidase and manganese(II) peroxidase from the white-rot basidiomycete Trametes versicolor. II. Partial sequences, peptide maps, and amino acid and carbohydrate compositions. 842 91

Lignin peroxidase H2 (LP-H2) from Phanerochaete chrysosporium oxidized 4-chloroaniline to form several oligomers. Included among the compounds identified were: 4,4'-dichloroazobenzene, 2-(4-chloroanilino)-5-hydroxybenzoquinone-di-4-chloroanil and 2-amino-5-(4-chloroanilino) benzoquinone-di-4-chloroanil. In contrast to results by others, we showed that oligomers of 4-chloroaniline were also formed by the fungus in vivo. It was also demonstrated that, although these potentially toxic intermediates are made, they are also degraded.
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PMID:Oligomers of 4-chloroaniline are intermediates formed during its biodegradation by Phanerochaete chrysosporium. 847 15


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