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

---

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

This study characterizes the effect of oxygen concentration on the synthesis of ligninolytic enzymes by Phanerochaete chrysosporium immobilized on polyurethane foam cubes in a nonimmersed liquid culture system and maintained under different carbon-to-nitrogen (C/N) ratios and levels. Lignin peroxidase (LIP) activity was obtained in cultures exposed to air when the C/N ratio was low (7.47), i.e., when nitrogen levels were high (C/N = 56/45 mM) or carbon levels were low (C/N = 5.6/4.5 mM). At the low C/N ratio, the fungus was carbon starved and did not produce extracellular polysaccharides. At a high C/N ratio (153), i.e., under conditions of excess carbon (nitrogen limitation) (C/N = 56/2.2 mM), cultures exposed to air produced large amounts of polysaccharide, and LIP activity was detected only in cultures exposed to pure oxygen. Under high-nitrogen conditions, LIP production was 1,800 U/liter in cultures exposed to pure oxygen and 1,300 U/liter in cultures exposed to air, with H1 and H2 being the main isoenzymes. The oxygen level did not significantly alter the isoenzyme profile, nor did low-carbon conditions. The formation of manganese peroxidase was generally less affected by the oxygen level than that of LIP but was considerably reduced by a low C/N ratio. The effects of oxygen level and C/N ratio on the synthesis of glyoxal oxidase paralleled their effects on LIP synthesis except in the case of high nitrogen, which totally suppressed glyoxal oxidase activity.
...
PMID:Ligninolytic System Formation by Phanerochaete chrysosporium in Air. 1653 24

Lignin content and enzymes involved in lignification were measured in leaf discs of reed canarygrass (Phalaris arundinacea L.) inoculated with Helminthosporium avenae and floated on water or solutions of cycloheximide (25 mug/ml). Fungal germ tubes did not penetrate localized lignified swellings, which formed beneath penetration sites, in the outer epidermal wall of discs floated on water. Within 18 hours, inoculated discs on water had higher lignin content and higher activity of the enzymes phenylalanine ammonia lyase, tyrosine ammonia lyase, hydroxycinnamate-CoA ligase and peroxidase than noninoculated discs on water. When inoculated tissues were floated on cycloheximide solutions, increases in lignin content and enzyme activities associated with lignin biosynthesis were inhibited, and the tissue was susceptible to fungal penetration. Lignin biosynthesis at the site of attempted fungal penetration may play an important role in the resistant response of reed canarygrass to leaf-infecting fungi.
...
PMID:Regulation of lignin formation in reed canarygrass in relation to disease resistance. 1665 98

Tobacco (Nicotiana tabacum) plants transformed with a chimeric tobacco anionic peroxidase gene have previously been shown to synthesize high levels of peroxidase in all tissues throughout the plant. One of several distinguishable phenotypes of transformed plants is the rapid browning of pith tissue upon wounding. Pith tissue from plants expressing high levels of peroxidase browned within 24 hours of wounding, while tissue from control plants did not brown as late as 7 days after wounding. A correlation between peroxidase activity and wound-induced browning was observed, whereas no relationship between polyphenol oxidase activity and browning was found. The purified tobacco anionic peroxidase was subjected to kinetic analysis with substrates which resemble the precursors of lignin or polyphenolic acid. The purified enzyme was found to readily polymerize phenolic acids in the presence of H(2)O(2) via a modified ping-pong mechanism. The percentage of lignin and lignin-related polymers in cell walls was nearly twofold greater in pith tissue isolated from peroxidase-overproducer plants compared to control plants. Lignin deposition in wounded pith tissue from control plants closely followed the induction of peroxidase activity. However, wound-induced lignification occurred 24 to 48 hours sooner in plants overexpressing the anionic peroxidase. This suggests that the availability of peroxidase rather than substrate may delay polyphenol deposition in wounded tissue.
...
PMID:Wound-induced deposition of polyphenols in transgenic plants overexpressing peroxidase. 1666 24

The present study mainly investigated the ability of solid-state cultures of the non-pathogenic Fusarium oxysporum strain BAFC 738 to transform aromatic components to reduce the phytotoxicity in olive-mill dry residue (DOR), the waste from the two-phase manufacturing process. Lignin, hemicellulose, fats and water-soluble extractives contents of DOR colonized by the fungus for 20 weeks were reduced by 16%, 25%, 71% and 13%, respectively, while the cellulose content increased by 25%. In addition, the ethyl acetate-extractable phenolic fraction of the waste was reduced by 65%. However, mass-balance ultra-filtration and size-exclusion chromatography experiments suggested that the apparent removal of that fraction, mainly including 2-(3,4-dihydroxyphenyl)ethyl alcohol and 2-(4-hydroxyphenyl)ethyl alcohol, was due to polymerization. Mn-peroxidase and Mn-independent peroxidase activities were found in F. oxysporum solid-state cultures, while laccase and aryl alcohol oxidase activities were not detected. Tests performed with seedlings of tomato (Lycopersicum esculentum L.), soybean (Glycine maximum Merr.), and alfalfa (Medicago sativa L.) grown on soils containing 6% (w/w) of bioconverted DOR (kg soil)(-1) showed that the waste's phytotoxicity was removed by 20 weeks-old fungal cultures. By contrast, the same material exhibited a high residual toxicity towards lettuce (Lactuca sativa L.).
...
PMID:Solid-state cultures of Fusarium oxysporum transform aromatic components of olive-mill dry residue and reduce its phytotoxicity. 1720 20

Lentinula edodes, commonly called shiitake, is considered a choice edible mushroom with exotic taste and medicinal quality. L. edodes grows very well and produces a range of enzymes when cultivated on eucalyptus residues. Development of appropriate experimental procedures for recovery and determination of enzymes became a widely important cash crop. In this work, enzymes produced by L. edodes were extracted using different pH buffer and determined regarding peroxidases and proteases. Lignin peroxidase (LiP) was not detected in the extracts based on veratryl alcohol or azure B oxidation. Proteases were very low while Mn-peroxidases (MnP) predominated. The optimal pH for MnP recovery was 5.0, under agitation at 25 degrees C. The oxidation of phenol red decreased after dark-colored small compounds or ions were eliminated by dialysis. The extract of L. edodes contained components of high molecular weight, such as proteases or high polyphenol, that could be involved in the LiP inactivation. L. edodes sample previously submitted to dialysis was also joined to LiP of Phanerochaete chrysosporium and a total inhibition of LiP was observed.
...
PMID:Extraction of manganese peroxidase produced by Lentinula edodes. 1758 98

Lignin biosynthesis is a major carbon sink in gymnosperms and woody angiosperms. Many of the enzymes involved are encoded for by several genes, some of which are also related to the biosynthesis of other phenylpropanoids. In this study, we aimed at the identification of those gene family members that are responsible for developmental lignification in Norway spruce (Picea abies (L.) Karst.). Gene expression across the whole lignin biosynthetic pathway was profiled using EST sequencing and quantitative real-time RT-PCR. Stress-induced lignification during bending stress and Heterobasidion annosum infection was also studied. Altogether 7,189 ESTs were sequenced from a lignin forming tissue culture and developing xylem of spruce, and clustered into 3,831 unigenes. Several paralogous genes were found for both monolignol biosynthetic and polymerisation-related enzymes. Real-time RT-PCR results highlighted the set of monolignol biosynthetic genes that are likely to be responsible for developmental lignification in Norway spruce. Potential genes for monolignol polymerisation were also identified. In compression wood, mostly the same monolignol biosynthetic gene set was expressed, but peroxidase expression differed from the vertically grown control. Pathogen infection in phloem resulted in a general up-regulation of the monolignol biosynthetic pathway, and in an induction of a few new gene family members. Based on the up-regulation under both pathogen attack and in compression wood, PaPAL2, PaPX2 and PaPX3 appeared to have a general stress-induced function.
...
PMID:Expression profiling of the lignin biosynthetic pathway in Norway spruce using EST sequencing and real-time RT-PCR. 1776 1

Lignin degradation by fungal peroxidases is initiated by one-electron transfer to an exposed tryptophan radical, a reaction mediated by veratryl alcohol (VA) in lignin peroxidase (LiP). Versatile peroxidase (VP) differs not only in its oxidation of Mn2+ at a second catalytic site but also in its ability to directly oxidize different aromatic compounds. The catalytic tryptophan environment was compared in LiP and VP crystal structures, and six residues near VP Trp164 were modified by site-directed mutagenesis. Oxidation of Mn2+ was practically unaffected. However, several mutations modified the oxidation kinetics of the high-redox-potential substrates VA and Reactive Black 5 (RB5), demonstrating that other residues contribute to substrate oxidation by the Trp164 radical. Introducing acidic residues at the tryptophan environment did not increase the efficiency of VP oxidizing VA. On the contrary, all variants harboring the R257D mutation lost their activity on RB5. Interestingly, this activity was restored when VA was added as a mediator, revealing the LiP-type behavior of this variant. Moreover, combination of the A260F and R257A mutations strongly increased (20-50-fold) the apparent second-order rate constants for reduction of VP compounds I and II by VA to values similar to those found in LiP. Dissociation of the enzyme-product complex seemed to be the limiting step in the turnover of this improved variant. Nonexposed residues in the vicinity of Trp164 can also affect VP activity, as found with the M247F mutation. This was a direct effect since no modification of the surrounding residues was found in the crystal structure of this variant.
...
PMID:Site-directed mutagenesis of the catalytic tryptophan environment in Pleurotus eryngii versatile peroxidase. 1820 Nov 5

The production of biomass and ligninolytic enzymes by Pleurotus ostreatus was analysed in synthetic medium with yeast extract and different glucose concentrations (0.5 - 20 g/l), at different pH (3.5-6.5) and incubation temperatures (23-32 degrees C). The best culture condition were: initial glucose concentration of 5 g/l, initial pH between 5.5-6.5 and incubation temperature between 26-29 degrees C. The saturation constant for glucose (Ks) was 1.75 g/l. The biomass concentration reached 8.6 g/l with a glucose addition of 20.0 g/l to the culture medium. The control of pH allowed an increment of 0.5 g/l of biomass concentration. The birreactor produced pellets with a homogeneous distribution of diameter size of 3.4 -/+ 0.2 mm. Approximately, 307 U/l of laccase and 0.41 U/l of manganese peroxidase were obtained in extracellular liquid medium and 0.015 U/g of laccase and 0.809 U/g of manganese peroxidase were obtained in solid substrate. Lignin peroxidase activity was not detected at any condition.
...
PMID:[Production of biomass and ligninolytic enzymes by Pleurotus ostreatus in submerged culture.]. 1847 24

A strict screening strategy for microorganism selection was followed employing a number of white-rot fungi for the bioremediation of textile effluent, which was generated from one Ireland-based American textile industry. Finally, one fungus Bjerkandera adusta has been investigated in depth for its ability to simultaneously degrade and enrich the nutritional quality of highly coloured textile effluent-adsorbed barley husks through solid-state fermentation (SSF). Certain important parameters such as media requirements, moisture content, protein/biomass production and enzyme activities were examined in detail. A previously optimised method of dye desorption was employed to measure the extent of dye remediation through effluent decolorisation achieved as a result of fungal activity in SSF. B. adusta was capable of decolourising a considerable concentration of the synthetic dye effluent (up to 53%) with a moisture content of 80-85%. Protein enrichment of the fermented mass was achieved to the extent of 229 g/kg dry weight initial substrate used. Lignin peroxidase and laccase were found to be the two main enzymes produced during SSF of the dye-adsorbed lignocellulosic waste residue.
...
PMID:Remediation of textile dye waste water using a white-rot fungus Bjerkandera adusta through solid-state fermentation (SSF). 1849 71

Lignin peroxidase was purified (72-fold) from Acinetobacter calcoaceticus NCIM 2890. The purified lignin peroxidase (55-65 kDa) showed dimeric nature. The maximum enzyme activity was observed at pH 1.0, between a broad temperature range of 50 and 70 degrees C, at H2O2 concentration (40 mM) and the substrate concentration (n-propanol, 100 mM). Purified lignin peroxidase was able to oxidize a variety of substrates including Mn2+, tryptophan, mimosine, L-Dopa, hydroquinone, xylidine, n-propanol, veratryl alcohol, and ten textile dyes of various groups indicating as a versatile peroxidase. Most of the dyes decolorized up to 90%. Tryptophan stabilizes the lignin peroxidase activity during decolorization of dyes.
...
PMID:Purification and partial characterization of lignin peroxidase from Acinetobacter calcoaceticus NCIM 2890 and its application in decolorization of textile dyes. 1850 30


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---