Inactivation Mechanism of Ascorbate Peroxidase at Low Concentrations of Ascorbate; Hydrogen Peroxide Decomposes Compound I of Ascorbate Peroxidase
نویسندگان
چکیده
منابع مشابه
Kinetic study of the inactivation of ascorbate peroxidase by hydrogen peroxide.
The activity of ascorbate peroxidase (APX) has been studied with H(2)O(2) and various reducing substrates. The activity decreased in the order pyrogallol>ascorbate>guaiacol>2, 2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS). The inactivation of APX with H(2)O(2) as the sole substrate was studied. The number of H(2)O(2) molecules required for maximal inactivation of the enzyme was d...
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Even under optimal conditions, many metabolic processes, including the chloroplastic, mitochondrial, and plasma membrane-linked electron transport systems of higher plants, produce active oxygen species (AOS). Furthermore, the imposition of biotic and abiotic stress conditions can give rise to excess concentrations of AOS, resulting in oxidative damage at the cellular level. Therefore, antioxid...
متن کاملZonal changes in ascorbate and hydrogen peroxide contents, peroxidase, and ascorbate-related enzyme activities in onion roots.
Onion (Allium cepa) roots growing hydroponically show differential zonal values for intra- (symplastic) and extra- (apoplastic) cellular ascorbate (ASC) and dehydroascorbate (DHA) contents and for related enzyme activities. In whole roots, ASC and DHA concentrations were higher in root apex and meristem and gradually decreased toward the root base. Guaiacol peroxidase, ASC peroxidase, monodehyd...
متن کاملEngineering the active site of ascorbate peroxidase.
The oxidation of a number of thioethers, namely methyl phenyl sulphide (1), ethyl phenyl sulphide (2), isopropyl phenyl sulphide (3), n-propyl phenyl sulphide (4), p-chlorophenyl methyl sulphide (5), p-nitrophenyl methyl sulphide (6) and methyl naphthalene sulphide (7), by recombinant pea cytosolic ascorbate peroxidase (rAPX) and a site-directed variant of rAPX in which the distal tryptophan 41...
متن کاملAscorbate in pharmacologic concentrations selectively generates ascorbate radical and hydrogen peroxide in extracellular fluid in vivo.
Ascorbate (ascorbic acid, vitamin C), in pharmacologic concentrations easily achieved in humans by i.v. administration, selectively kills some cancer cells but not normal cells. We proposed that pharmacologic ascorbate is a prodrug for preferential steady-state formation of ascorbate radical (Asc(*-)) and H(2)O(2) in the extracellular space compared with blood. Here we test this hypothesis in v...
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ژورنال
عنوان ژورنال: Plant and Cell Physiology
سال: 1996
ISSN: 0032-0781,1471-9053
DOI: 10.1093/oxfordjournals.pcp.a028963