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An enzyme that catalyzes reactions in which hydrogen peroxide is an electron acceptor.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



any of a group of enzymes of the oxidoreduc-tase class that catalyze the hydrogen-peroxide-mediated or organic-peroxide-mediated oxidation of various polyphenols and aliphatic and aromatic amines, as well as of fatty acids, cytochromes, and glutathione. The peroxidases whose substrates are fatty acids, cytochromes, and glutathione are called fatty-acid peroxidase, cytochrome peroxidase, and glutathione peroxidase, respectively. Depending on the source from which they are isolated, peroxidases vary in molecular weight and substrate specificity. The most widely distributed and well-studied peroxidase is of plant origin, usually obtained from horseradish; its molecular weight is 44,100. The prosthetic group of plant peroxidases resembles heme, which is the prosthetic group of hemoglobin; indeed, hemoglobin does exhibit slight peroxidase activity. Plant peroxidases are important in respiration: together with polyphenol oxidase, they catalyze the oxidative conversion of respiratory chromogens into respiratory pigments.

Small amounts of peroxidase are found in animals, and only in white blood cells and milk. Horseradish peroxidase is used in the laboratory to determine the glucose level of blood and urine and to mark lysosomes in cytochemical studies.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Plants developed a complex system of protection through oxidant detoxification, where the actions of antioxidant enzymes (peroxidase, catalase) are essential to neutralize the effects of ROS on the cells (Joshi and Chinnusamy 2014; Harsh et al., 2016).
Polyphenol oxidase and peroxidases in fruits and vegetables.
Each test was conducted with three replications for each concentration and activity of peroxidase in the gills was compared with that of control fish.
Foliar spray by JA especially (0.3 uM) gave the highest peroxidase and polyphenol oxidase enzymes activity under normal or stress condition.
In an attempt to assess the peroxidase activity of PIC1 in a scenario mimicking intravascular hemolysis, the following experiment was performed.
Tg-Hb peroxidase activity decreased drastically with the addition of SDS at increasing concentrations (Figure 4(d)).
In this way, a correlation between the factor of tetragonal elongation and peroxidase activity has been already reported [14, 15].
[SCN.sup.-] and [H.sub.2][O.sub.2] are catalyzed into [OSCN.sup.-] by three peroxidases--myeloperoxidase (MPO), eosinophil peroxidase (EPX), and lactoperoxidase (LPO)--expressed in neutrophils, eosinophils, and epithelial cells, respectively, in the lung tissue.
Among deficient subjects, antithyroid peroxidase levels were significantly higher than levels measured in the sufficient group.