Selenium: Biochemical Role as a Component of Glutathione Peroxidase
09 Feb 1973-Science (American Association for the Advancement of Science)-Vol. 179, Iss: 4073, pp 588-590
TL;DR: When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H2O2, added glutathione failed to protect the hemoglobin from oxidative damage.
Abstract: When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H(2)O(2), added glutathione failed to protect the hemoglobin from oxidative damage. This occurred because the erythrocytes were practically devoid of glutathione-peroxidase activity. Extensively purified preparations of glutathione peroxidase contained a large part of the (75)Se of erythrocytes labeled in vivo. Many of the nutritional effects of selenium can be explained by its role in glutathione peroxidase.
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TL;DR: Two peaks of glutathione peroxidase activity were present in the Sephadex G-150 gel filtration chromatogram of rat liver supernatant when 1.5 mM cumene hydroperoxide was used as substrate, and the second peak represents a second glutathienase activity which catalyzes the destruction of organic hydroperoxides but has little activity toward H 2 O 2 and which persists in severe selenium deficiency.
Abstract: Glutathione peroxidase activity in the liver supernatant from rats fed a Se-deficient diet for 2 weeks was 8% of control when measured with H 2 O 2 but 42% of control when assayed with cumene hydroperoxide. Two peaks of glutathione peroxidase activity were present in the Sephadex G-150 gel filtration chromatogram of rat liver supernatant when 1.5 mM cumene hydroperoxide was used as substrate. Only the first peak was detected when 0.25 mM H 2 O 2 was used as substrate. The first peak was absent from chromatograms of Se-deficient rat liver supernatants; but the second peak, which eluted at a position corresponding to M.W. = 39,000, appeared unchanged. The second peak thus represents a second glutathione peroxidase activity which catalyzes the destruction of organic hydroperoxides but has little activity toward H 2 O 2 and which persists in severe selenium deficiency.
3,181 citations
TL;DR: This article serves as introduction to the FRBM Forum on glutathione and emphasizes cellular functions: What is GSH?
Abstract: Glutathione (GSH) is the major cellular thiol participating in cellular redox reactions and thioether formation. This article serves as introduction to the FRBM Forum on glutathione and emphasizes cellular functions: What is GSH? Where does it come from? Where does it go? What does it do? What is new and noteworthy? Research tools, historical remarks, and links to current trends.
1,607 citations
TL;DR: The development of new organochalcogens with higher thiol-peroxidase activity that can use other non-toxic thiol reducing agents, such as N-acetylcysteine instead of glutathione, will permit the investigation of the co-administration of organochAlcogens and thiols as a formulation for antioxidant therapy.
Abstract: The organoselenium and organotellurium compounds have been described as promising pharmacological agents in view of their unique biological properties. Glutathione peroxidase mimic, antioxidant activity and thioredoxin reductase inhibition are some of the properties reviewed here. On the other hand, little is known about the molecular toxicological effects of organoselenium and organotellurium compounds. Most of our knowledge arose from research on inorganic selenium and tellurium. However, the ability to oxidize sulfhydryl groups from biological molecules can be involved both in their pharmacological properties and in their toxicological effects. In fact, exposition to high doses of organoselenium or to low doses of organotellurium causes the depletion of endogenous reduced glutathione in a variety of tissues. Thus, the design of compounds that cause low depletion of glutathione and react with specific targeted proteins, controlling specific metabolic pathways, will represent an important progress in understanding the field of organochalcogen compounds. Furthermore, the development of new organochalcogens with higher thiol-peroxidase activity that can use other non-toxic thiol reducing agents, such as N-acetylcysteine instead of glutathione, will permit the investigation of the co-administration of organochalcogens and thiols as a formulation for antioxidant therapy.
1,572 citations
TL;DR: This review systematically introduces the classification, catalytic mechanism, activity regulation as well as recent research progress of nanozymes in the field of biosensing, environmental protection, and disease treatments, etc. in the past years.
Abstract: Because of the high catalytic activities and substrate specificity, natural enzymes have been widely used in industrial, medical, and biological fields, etc. Although promising, they often suffer from intrinsic shortcomings such as high cost, low operational stability, and difficulties of recycling. To overcome these shortcomings, researchers have been devoted to the exploration of artificial enzyme mimics for a long time. Since the discovery of ferromagnetic nanoparticles with intrinsic horseradish peroxidase-like activity in 2007, a large amount of studies on nanozymes have been constantly emerging in the next decade. Nanozymes are one kind of nanomaterials with enzymatic catalytic properties. Compared with natural enzymes, nanozymes have the advantages such as low cost, high stability and durability, which have been widely used in industrial, medical, and biological fields. A thorough understanding of the possible catalytic mechanisms will contribute to the development of novel and high-efficient nanozymes, and the rational regulations of the activities of nanozymes are of great significance. In this review, we systematically introduce the classification, catalytic mechanism, activity regulation as well as recent research progress of nanozymes in the field of biosensing, environmental protection, and disease treatments, etc. in the past years. We also propose the current challenges of nanozymes as well as their future research focus. We anticipate this review may be of significance for the field to understand the properties of nanozymes and the development of novel nanomaterials with enzyme mimicking activities.
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6,289 citations
1,133 citations
TL;DR: The most plausible route for the conversion of hemoglobin into biliverdin in vivo is through the oxidation and opening of the tetrapyrrole ring, after which the globin and iron are removed as discussed by the authors.
Abstract: Although the exact mechanism of the conversion of hemoglobin into biliverdin in vivo is still in doubt, the most plausible route is through the oxidation and opening of the tetrapyrrole ring, after which the globin and iron are removed. This reaction scheme is based on the extensive chemical studies of Lemberg and Legge (1) and on the more recent work of Kaziro el al. (2-4). In these studies, the oxidation of the tetrapyrrole ring was brought about under physiological conditions of pH and temperature by a coupled oxidation with ascorbic acid. Presumably, ascorbic acid reacts with the oxygen of oxyhemoglobin to produce a constant supply of hydrogen peroxide. This, in turn, oxidizes either the iron or the tetrapyrrole ring of hemoglobin. Two distinct intermediates are produced in this chemical breakdown of hemoglobin. Choleglobin, which is formed first, has a distinctive absorption band at 627 to 630 rnp after treatment with carbon monoxide and sodium hydrosulfite. As the reaction proceeds further, the appearance of an absorption band at 760 rnp is indicative of the presence of verdohemoglobin. Treatment with glacial acetic acid and ether will quantitatively convert verdohemoglobin into biliverdin. One of the problems of hemoglobin catabolism has been the explanation of the remarkable stability of hemoglobin in the intact cell to materials which would ordinarily destroy it, Ascorbic acid is a normal constituent of the red blood cell, and hydrogen peroxide presumably is generated constantly in small amounts within the cell. Even oxygen brings about a rather rapid autoxidation of hemoglobin in solutions of crystalline oxyhemoglobin (5). Foulkes and Lemberg (6) and Kaziro and coworkers (2) have previously shown the importance of catalase in protecting hemoglobin from oxidative breakdown produced by ascorbic acid. In addition, Foulkes and Lemberg (6) have shown that catalase will give some protec
722 citations
01 Jan 1957
TL;DR: Although the exact mechanism of the conversion of hemoglobin into biliverdin in vivo is still in doubt, the most plausible route is through the oxidation and opening of the tetrapyrrole ring, after which the globin and iron are removed.
Abstract: Although the exact mechanism of the conversion of hemoglobin into biliverdin in vivo is still in doubt, the most plausible route is through the oxidation and opening of the tetrapyrrole ring, after which the globin and iron are removed. This reaction scheme is based on the extensive chemical studies of Lemberg and Legge (1) and on the more recent work of Kaziro el al. (2-4). In these studies, the oxidation of the tetrapyrrole ring was brought about under physiological conditions of pH and temperature by a coupled oxidation with ascorbic acid. Presumably, ascorbic acid reacts with the oxygen of oxyhemoglobin to produce a constant supply of hydrogen peroxide. This, in turn, oxidizes either the iron or the tetrapyrrole ring of hemoglobin. Two distinct intermediates are produced in this chemical breakdown of hemoglobin. Choleglobin, which is formed first, has a distinctive absorption band at 627 to 630 rnp after treatment with carbon monoxide and sodium hydrosulfite. As the reaction proceeds further, the appearance of an absorption band at 760 rnp is indicative of the presence of verdohemoglobin. Treatment with glacial acetic acid and ether will quantitatively convert verdohemoglobin into biliverdin. One of the problems of hemoglobin catabolism has been the explanation of the remarkable stability of hemoglobin in the intact cell to materials which would ordinarily destroy it, Ascorbic acid is a normal constituent of the red blood cell, and hydrogen peroxide presumably is generated constantly in small amounts within the cell. Even oxygen brings about a rather rapid autoxidation of hemoglobin in solutions of crystalline oxyhemoglobin (5). Foulkes and Lemberg (6) and Kaziro and coworkers (2) have previously shown the importance of catalase in protecting hemoglobin from oxidative breakdown produced by ascorbic acid. In addition, Foulkes and Lemberg (6) have shown that catalase will give some protec
660 citations
658 citations