• Ascorbate-dependent peroxidase activity was first reported in 1979,, more than 150 years after the first observation of peroxidase activity in horseradish plants and almost 40 years after the discovery of the closely related cytochrome c peroxidase enzyme. (wikipedia.org)
  • This structure provides new rationalization of the unusual functional features of the related cytochrome c peroxidase enzyme, and a mechanism for electron transfer from the substrate to the heme has been prepared (Chapter 3). (le.ac.uk)
  • APX enzymes show high specificity for ascorbate as an electron donor, but most APXs will also oxidise other organic substrates that are more characteristic of the class III peroxidases (such as horseradish peroxidase), in some cases at rates comparable to that of ascorbate itself. (wikipedia.org)
  • Although the activities of most antioxidant and sulfur metabolism-related enzymes and glyoxalase I and the level of reduced glutathione in the Mg-deficient leaves and roots and the level of ascorbate in the leaves were kept in higher levels, the levels of malonaldehyde and MG and/or electrolyte leakage were increased in the Mg-deficient lower and upper leaves and roots, especially in the Mg-deficient lower leaves and roots. (biomedcentral.com)
  • APXs catalyse the H2O2-dependent oxidation of ascorbate in plants, algae and certain cyanobacteria. (wikipedia.org)
  • X-ray crystallography, kinetics, spectroscopy and directed evolution have been used to define substrate binding in recombinant soybean cystolic ascorbate peroxidase (rsAPX), which catalyses the hydrogen peroxide-dependent oxidation of ascorbate in plants. (le.ac.uk)
  • Light-controlled expression of a gene encoding L-galactono-γ-lactone dehydrogenase which affects ascorbate pool size in Arabidopsis thaliana. (researchmap.jp)
  • Ascorbate peroxidase (or L-ascorbate peroxidase, APX) (EC 1.11.1.11) is an enzyme that catalyzes the chemical reaction L-ascorbate + H2O2 ⇌ {\displaystyle \rightleftharpoons } dehydroascorbate + 2 H2O It is a member of the family of heme-containing peroxidases. (wikipedia.org)
  • Isolation and characterisation of a cDNA encoding a novel cytosolic ascorbate peroxidase from potato plants (Solanum tuberosum L.) . Acta Physiologiae Plantarum, 28 (1), 41 - 47. (up.pt)
  • Under physiological conditions, the immediate product of the reaction, the monodehydroascorbate radical, is reduced back to ascorbate by a monodehydroascorbate reductase (monodehydroascorbate reductase (NADH)) enzyme. (wikipedia.org)
  • In the absence of a reductase, two monodehydroascorbate radicals disproportionate rapidly to dehydroascorbic acid and ascorbate. (wikipedia.org)
  • In addition, levels of ascorbate peroxidase activity increased slightly and levels of monodehydroascorbate reductase were elevated by about three-fold in GST/GPX-expressing plants. (usda.gov)
  • Most of parameters involved in ROS and MG metabolisms had similar variation trends and degrees between the Mg-deficient lower leaves and roots, but several parameters (namely glutathione S-transferase, sulfite reductase, ascorbate and dehydroascorbate) displayed the opposite variation trends. (biomedcentral.com)
  • Some proteins from the APX family lack the ascorbate-binding amino acid residues suggesting that they might oxidize other molecules than ascorbate. (wikipedia.org)
  • In water solutions, this substance is present as a monovalent anion, ascorbate- (Asc-), which easily donates electrons to oxidized molecules and scavenges reactive oxygen species (ROS). (deepdyve.com)
  • Moreover, combined treatment with Se and Mo increased the lignin content and cell wall thickness by upregulating the expression levels of genes encoding cinnamyl alcohol dehydrogenase (CAD), peroxidase (POX) and phenylalanine amino-lyase (PAL), involved in lignin biosynthesis. (bvsalud.org)
  • This enzyme participates in ascorbate and aldarate metabolism. (wikipedia.org)
  • These results indicate that overexpression of GST/GPX in transgenic tobacco seedlings provides increased glutathione-dependent peroxide scavenging and alterations in ascorbate metabolism which lead to reduced oxidative stress. (usda.gov)
  • Only ascorbate was found to protect the lungs against lipid peroxidation. (cdc.gov)
  • The apparent protection of metabolic activity in GST/GPX-expressing seedlings corresponded with decreased lipid peroxidation and maintenance of the ascorbate pool in a more reduced state. (usda.gov)
  • The binding interaction of soybean cytosolic APX with its physiological substrate, ascorbate, and with a number of other substrates are also known. (wikipedia.org)
  • Understanding functional diversity and substrate specificity in haem peroxidases: what can we learn from ascorbate peroxidase? (wikipedia.org)
  • The redox-sensitive transcription factor RAP2.4a mediates chloroplast-to-nucleus redox signaling and controls induction of the three most prominent chloroplast peroxidases, namely 2-Cys peroxiredoxin A (2CPA) and thylakoid- and stromal ascorbate peroxidase (tAPx and sAPx). (fu-berlin.de)
  • The systematic name of this enzyme class is L-ascorbate:hydrogen-peroxide oxidoreductase. (wikipedia.org)
  • This mechanism may underlie ascorbate release, signalling phenomena, apoplastic redox reactions, iron acquisition, and control the ionic and electrical equilibrium (together with K+ efflux via GORK channels). (deepdyve.com)
  • Collectively, the data show that all three members of the class I heme peroxidases can support radical formation on the distal tryptophan and that the reactivity of this radical can be controlled either by the protein structure or by the nature of the compound I intermediate. (bris.ac.uk)
  • This means that defining an enzyme as an APX is not straightforward, but is usually applied when the specific activity for ascorbate is higher than that for other substrates. (wikipedia.org)
  • Within the transcription factor family, RAP2.4a has a unique function as a general transcriptional activator of chloroplast peroxidase activity. (fu-berlin.de)
  • 2,3,7,8-Tetrachlorodibenzo- p -dioxin as an antiestrogen: Effect on rat uterine peroxidase activity. (cdc.gov)
  • EPR spectroscopy measurements demonstrate that salinity (NaCl) triggers the accumulation of root apoplastic ascorbyl radicals in an A9C-dependent manner, confirming that l-ascorbate leaks through anion channels under depolarization. (deepdyve.com)
  • This ensures the availability of ascorbate for its protective function. (cdc.gov)
  • In basil, the increased levels of low molecular weight antioxidants such as phenols and flavonoids were observed, while in oregano, ascorbate, glutathione, and phenols were enhanced. (tubitak.gov.tr)
  • APX is an integral component of the glutathione-ascorbate cycle. (wikipedia.org)
  • Peroxidases have been classified into three types (class I, class II and class III): ascorbate peroxidases is a class I peroxidase enzyme. (wikipedia.org)
  • The authors note that an active transport system for ascorbate exists in lung cells. (cdc.gov)
  • Ascorbate peroxidase has vital defensive role against ROS [ 17 ] and can catalyze the breakdown of H 2 O 2 that is produced by SOD. (hindawi.com)
  • Exogenous ascorbate also induces a moderate increase in programmed cell death symptoms in intact roots, but it does not activate Ca2+ influx currents in patch-clamped root protoplasts. (deepdyve.com)
  • These data show that apoplastic redox-active transition metals are involved in the ascorbate-induced [Ca2+]cyt. (deepdyve.com)