Production of the superoxide radical by horseradish peroxidase.
نویسندگان
چکیده
The reaction mixture contained, in a total volume of 1.00m1, enzyme, p-coumaric acid (2.5pmol), dihydroxyfumaric acid (30pmol), KH2P04 (8.3pmol) and sufficient KOH to adjust the pH to 6. Incubations were carried out for 0.5h at 25°C and caffeic acid production was assayed as described by Halliwell(l975). 100% corresponded to a rate of 60nmol of caffeic acid formed in 0.5h. Oxidation of dihydroxyfumarate was followed by the decrease in E300 (althoughp-coumaric acid also absorbs light at 300nm, very little is used up during a 30min incubation). Samples (10~1) were removed from the reaction mixture at intervals, added to lOml of water and the absorbance recorded at once. Units of superoxide dismutase were as described by McCord & Fridovich (1969).
منابع مشابه
Enzymatic and nonenzymatic superoxide-generating reactions of isoniazid.
During the course of horseradish peroxidase-mediated oxidation of either o-dianisidine or 2-2'-azino-di(3-ethyl-benzthiazoline-6-sulfonic acid) (ABTS), no O2 consumption took place. When isonicotinic acid hydrazide (isoniazid) (INH) was included in the reaction mixture, O2 was consumed in amounts linearly related to the INH concentration. Nicotinic acid hydrazide at equimolar concentrations ind...
متن کاملIndole-3-acetic Acid oxidation and crocin bleaching by horseradish peroxidase.
During indoleacetic acid (IAA) oxidation by horseradish peroxidase the water soluble model polyene, crocin, is bleached. IAA-oxidation and crocin bleaching are stimulated at acidic pH as well as by the monophenol p-hydroxyacetophenone. IAA oxidation and crocin bleaching are neither influenced by catalase or superoxide dismutase nor by different OH-radical scavengers, whereas both ascorbate and ...
متن کاملHydroxyl-radical production in physiological reactions. A novel function of peroxidase.
Peroxidases catalyze the dehydrogenation by hydrogen peroxide (H2O2) of various phenolic and endiolic substrates in a peroxidatic reaction cycle. In addition, these enzymes exhibit an oxidase activity mediating the reduction of O2 to superoxide (O2.-) and H2O2 by substrates such as NADH or dihydroxyfumarate. Here we show that horseradish peroxidase can also catalyze a third type of reaction tha...
متن کاملEnzymatic Activation of Hydrazine Derivatives
The oxidative metabolism of hydralazine, isoniazid, iproniazid, and phenylhydrazine has been studied using spin-trapping techniques. The oxidation of these hydrazine derivatives, catalyzed by horseradish peroxidase and prostaglandin synthetase, produces reactive free radical intermediates. Enzymatic activation of hydralazine produce the nitrogen-centered hydralazyl radical (RNHNH.); phenylhydra...
متن کاملOxygen radicals in cerebral ischemia.
Superoxide production was measured as the superoxide dismutase (SOD)-inhibitable portion of nitro blue tetrazolium (NBT) reduction after cerebral ischemia-reperfusion in anesthetized cats equipped with cranial windows. Significant superoxide production was found in the early reperfusion period and continued for more than 1 h after ischemia. Superoxide was not detected in control animals not sub...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Biochemical Society transactions
دوره 4 1 شماره
صفحات -
تاریخ انتشار 1976