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Chemical Speciation of Selenium and Mercury as Determinant of Their Neurotoxicity. ADVANCES IN NEUROBIOLOGY 2017; 18:53-83. [PMID: 28889263 DOI: 10.1007/978-3-319-60189-2_4] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The antagonism of mercury toxicity by selenium has been well documented. Mercury is a toxic metal, widespread in the environment. The main target organs (kidneys, lungs, or brain) of mercury vary depending on its chemical forms (inorganic or organic). Selenium is a semimetal essential to mammalian life as part of the amino acid selenocysteine, which is required to the synthesis of the selenoproteins. This chapter has the aim of disclosing the role of selenide or hydrogen selenide (Se-2 or HSe-) as central metabolite of selenium and as an important antidote of the electrophilic mercury forms (particularly, Hg2+ and MeHg). Emphasis will be centered on the neurotoxicity of electrophile forms of mercury and selenium. The controversial participation of electrophile mercury and selenium forms in the development of some neurodegenerative disease will be briefly presented. The potential pharmacological use of organoseleno compounds (Ebselen and diphenyl diselenide) in the treatment of mercury poisoning will be considered. The central role of thiol (-SH) and selenol (-SeH) groups as the generic targets of electrophile mercury forms and the need of new in silico tools to guide the future biological researches will be commented.
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Gonzalez-Flores JN, Shetty SP, Dubey A, Copeland PR. The molecular biology of selenocysteine. Biomol Concepts 2015; 4:349-65. [PMID: 25436585 DOI: 10.1515/bmc-2013-0007] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 03/22/2013] [Indexed: 01/11/2023] Open
Abstract
Selenium is an essential trace element that is incorporated into 25 human proteins as the amino acid selenocysteine (Sec). The incorporation of this amino acid turns out to be a fascinating problem in molecular biology because Sec is encoded by a stop codon, UGA. Layered on top of the canonical translation elongation machinery is a set of factors that exist solely to incorporate this important amino acid. The mechanism by which this process occurs, put into the context of selenoprotein biology, is the focus of this review.
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Poggi V, Del Vescovo V, Di Sanza C, Negri R, Hochkoeppler A. Selenite transiently represses transcription of photosynthesis-related genes in potato leaves. PHOTOSYNTHESIS RESEARCH 2008; 95:63-71. [PMID: 17846914 DOI: 10.1007/s11120-007-9233-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Accepted: 08/07/2007] [Indexed: 05/17/2023]
Abstract
A striking response of potato leaves to aspersion with selenite was observed at the transcriptional level by means of cDNA microarrays analysis. This response is characterized by a general transient repression of genes coding for components of photosynthetic systems and of other light-regulated genes. In particular, maximal repression was observed 8 h after selenite aspersion, while 24 h after the treatment a complete recovery of normal transcriptional levels was detected. Another general feature of the transcriptional response to selenite is represented by the transcriptional induction of genes related to amino acid metabolism, and to stress defense; interestingly, two genes coding for glutathione S-transferases were found early-induced upon selenite treatment.
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Affiliation(s)
- Valeria Poggi
- Department of Industrial Chemistry, University of Bologna, Viale Risorgimento 4, Bologna (I), 40136, Italy
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Affiliation(s)
- Albrecht Wendel
- a Biochemical Pharmacology, Faculty of Biology , POB 5560, D-7750 , Konstanz , Germany
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Mukherjee B, Basu M, Chatterjee M. Effect of selenomethionine on N-methylnitronitrosoguanidine-induced colonic aberrant crypt foci in rats. Eur J Cancer Prev 2001; 10:347-55. [PMID: 11535877 DOI: 10.1097/00008469-200108000-00008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
An association between low selenium intake and the incidence or prevalence of cancers is well known. Selenium in the form of selenomethionine supplemented in drinking water has been found to be highly effective in reducing tumour incidence and preneoplastic foci during the development of hepatocarcinogenesis in rats in our previous studies. Here, an attempt has been made to investigate whether the dose and form of selenium found to be effective during hepatocarcinogenesis is equally effective in N-methylnitronitrosoguanidine-induced colorectal carcinogenesis in terms of antioxidant defence enzyme systems, DNA chain breaks and incidences of aberrant crypt foci. Treatment with selenomethionine either on initiation or on selection/promotion, or during the entire experiment showed that selenomethionine was most effective in regulating the cellular antioxidant defence systems, DNA chain break control and reducing aberrant crypt foci in the colorectal tissues of rats. Our results also confirm that selenium is particularly effective in limiting the action of the carcinogen during the initiation phase of this colorectal carcinogenesis, just as we found with hepatocarcinogenesis in our previous studies.
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Affiliation(s)
- B Mukherjee
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh 160 014, India.
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Mukherjee B, Anbazhagan S, Roy A, Ghosh R, Chatterjee M. Novel implications of the potential role of selenium on antioxidant status in streptozotocin-induced diabetic mice. Biomed Pharmacother 1998; 52:89-95. [PMID: 9755800 DOI: 10.1016/s0753-3322(98)80008-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Levels of blood glucose, lipid peroxidation, glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) activities and blood selenium levels were determined in streptozotocin (STZ)-induced diabetic mice. The effect of oral administration of sodium selenite was studied on the above parameters. Diabetes caused hyperglycemia (2.8-fold increase) with a significant increase in the malondialdehyde levels (89% in liver and 83% in blood) and GST activity (55%) and marked decreases in GSH levels (approximately 73% in blood and 79% in liver) in the 5th week after STZ treatment as compared to normal control animals. Treatment of STZ-induced diabetic mice with sodium selenite changed these parameters to near control values in almost all cases. These results suggest that selenium plays a role in reducing the oxidative stress associated with diabetes.
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Affiliation(s)
- B Mukherjee
- Department of Pharmaceutical Technology, Jadavpur University, Calcutta, India
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Nakane T, Asayama K, Kodera K, Hayashibe H, Uchida N, Nakazawa S. Effect of selenium deficiency on cellular and extracellular glutathione peroxidases: immunochemical detection and mRNA analysis in rat kidney and serum. Free Radic Biol Med 1998; 25:504-11. [PMID: 9741586 DOI: 10.1016/s0891-5849(98)00078-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
To determine the effect of selenium (Se) deficiency on expression of glutathione peroxidase (GSH-Px) 1 and 2, we measured GSH-Px activity in rat serum, liver and kidneys, serum immunoreactive GSH-Px 2, and the mRNAs of kidney GSH-Px 1 and 2. We purified rat GSH-Px 2 and raised polyclonal antibodies. Immunoreactive GSH-Px 2 was measured by rocket immunoelectrophoresis. GSH-Px 2 was purified 1470-fold with a specific activity of 250 units/mg. Immunoblotting detected only GSH-Px 2 in rat serum, and much less GSH-Px 2 than GSH-Px 1 in kidney. Immunoblot signal of kidney GSH-Px 1 and 2 decreased progressively in Se deficient rats. Serum GSH-Px activity in Se deficient rats at 1, 2, 3, and 4 weeks declined to 33, 20, 10, and 9% of the control, while the serum level of immunoreactive GSH-Px 2 was 58, 24, 15, and 10% of the control, suggesting the presence of an inactive protein at week 1. GSH-Px activity declined to 4 and 11% of the control in the liver and kidney at 4 weeks. The mRNAs of kidney GSH-Px 1 and 2 showed similar decreases, and were 24 and 23% of the control at 4 weeks. GSH-Px mRNA levels were better preserved than GSH-Px activity, suggesting that GSH-Px expression was regulated at both pre-translational and translational levels.
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Affiliation(s)
- T Nakane
- Department of Pediatrics, Yamanashi Medical University, Tamahocho, Japan
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Mei H, Thakur A, Schwartz J, Lo Verde PT. Expression and characterization of glutathione peroxidase activity in the human blood fluke Schistosoma mansoni. Infect Immun 1996; 64:4299-306. [PMID: 8926102 PMCID: PMC174370 DOI: 10.1128/iai.64.10.4299-4306.1996] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Antioxidants may play an important role in immune evasion by schistosome parasites. Previous studies have focused on the roles of superoxide dismutase and glutathione S-transferase. In the present study, glutathione peroxidase (GPX) activity was measured in different fractions of worm extracts from several developmental stages of Schistosoma mansoni. The enzyme activity was shown to be developmentally regulated, with higher specific activities being found in the tegument-enriched Nonidet P-40 extract of adult worms (the stage least susceptible to immune killing) than in the larval stages (which are most susceptible to immune elimination). In all extracts tested, the activity against cumene hydroperoxide, even when glutathione S-transferase activity was removed, was higher than that for hydrogen peroxide. The expression of GPX cDNA in pGEX-2T by bacteria produced a 50-kDa fusion protein and a 32-kDa truncated protein. The latter was due to termination at the internal UGA codon that codes for selenocysteine. GPX activity was detected in the recombinantly produced GPX but not with Sj26-glutathione S-transferase from the vector. Mutating the TGA codon to TGT produced a full-length product, GPXm (19 kDa), that was used to produce 19 monoclonal antibodies. Anti-GPXm monoclonal antibodies recognized a 19-kDa molecule in adult-worm extract which, upon removal by immunoprecipitation, resulted in the loss of over 90% of the GPX activity, suggesting that a single form of GPX exists in the schistosome.
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Affiliation(s)
- H Mei
- Department of Microbiology, State University of New York, Buffalo 14214, USA
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Leonard JL, Leonard DM, Shen Q, Farwell AP, Newburger PE. Selenium-regulated translation control of heterologous gene expression: normal function of selenocysteine-substituted gene products. J Cell Biochem 1996; 61:410-9. [PMID: 8761945 DOI: 10.1002/(sici)1097-4644(19960601)61:3<410::aid-jcb8>3.0.co;2-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In eukaryotes, the synthesis of selenoproteins depends on an exogenous supply of selenium, required for synthesis of the novel amino acid, selenocysteine, and on the presence of a "selenium translation element" in the 3' untranslated region of mRNA. The selenium translation element is required to re-interpret the stop codon, UGA, as coding for selenocysteine incorporation and chain elongation. Messenger RNA lacking the selenium translation element and/or an inadequate selenium supply lead to chain termination at the UGA codon. We exploited these properties to provide direct translational control of protein(s) encoded by transfected cDNAs. Selenium-dependent translation of mRNA transcribed from target cDNA was conferred by mutation of an in-frame UGU, coding for cysteine, to UGA, coding for either selenocysteine or termination, then fusing the mutated coding region to a 3' untranslated region containing the selenium translation element of the human cellular glutathione peroxidase gene. In this study, the biological consequences of placing this novel amino acid in the polypeptide chain was examined with two proteins of known function: the rat growth hormone receptor and human thyroid hormone receptor beta 1. UGA (opal) mutant-STE fusion constructs of the cDNAs encoding these two polypeptides showed selenium-dependent expression and their selenoprotein products maintained normal ligand binding and signal transduction. Thus, integration of selenocysteine had little or no consequence on the functional activity of the opal mutants; however, opal mutants were expressed at lower levels than their wild-type counterparts in transient expression assays. The ability to integrate this novel amino acid at predetermined positions in a polypeptide chain provides selenium-dependent translational control to the expression of a wide variety of target genes, allows facile 75Se radioisotopic labeling of the heterologous proteins, and permits site-specific heavy atom substitution.
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Affiliation(s)
- J L Leonard
- Department of Physiology, University of Massachusetts Medical School, Worcester 01655, USA
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Abstract
Competitive binding assays were performed to determine the amount of binding of 75Se-labeled plasma selenoprotein P (PSP) to membranes from different rat tissues at physiologic pH. 75Se PSP for use as a ligand in the binding assays was labeled in vivo by injecting rats with 75Se selenious acid. PSP was obtained from plasma by salt precipitation and affinity and ion-exchange chromatography. Membranes for receptor assays were prepared from liver, kidney, testes, and brain of rats fed diets with either 0.01, 0.1, or 2 ppm selenium. At pH 7.4 PSP was bound differentially to tissues in the following order: brain > kidney > testes > liver. Specific binding of PSP to tissue membranes from rats fed the different levels of selenium increased with increasing amounts of dietary selenium. Saturation assays indicated apparent saturation of membrane receptors by the 75Se-labeled PSP. Another significant new finding was a 134-kDa complex of PSP and membrane receptor, identified by gel-filtration chromatography of cross-linked samples from binding assays. This provides evidence for a membrane receptor for PSP in rat tissues.
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Affiliation(s)
- D S Wilson
- Department of Food Science and Technology, University of California, Davis 95616
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Hawkes WC, Kutnink MA. High-performance liquid chromatographic determination of selenocysteine with the fluorescent reagent, N-(iodoacetylaminoethyl)-5-naphthylamine-1-sulfonic acid. JOURNAL OF CHROMATOGRAPHY 1992; 576:263-70. [PMID: 1400714 DOI: 10.1016/0378-4347(92)80200-a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The method described is based on derivatization of selenocysteine with N-(iodoacetylaminoethyl)-5-naphthylamine-1-sulfonic acid and responds linearly to selenocysteine spiked into plasma. Recovery is insensitive to inter-individual variation or use of serum versus plasma, but is decreased by hemolysis. The derivative is stable for at least three days. The total imprecision of determinations in plasma was 0.8-2.1% (coefficient of variation) over the range of 6-30 microM selenocysteine, with a detection limit of 0.4 microM (3 x S.D.). There was no significant interference from plasma thiols. This appears to be the first report of the selective reaction of free selenocysteine with a fluorescent reagent. This simple method works well in plasma and serum and may be adaptable to other types of samples.
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Affiliation(s)
- W C Hawkes
- USDA/ARS, Western Human Nutrition Research Center, Presidio of San Francisco, CA 94129
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Rocher C, Lalanne JL, Chaudière J. Purification and properties of a recombinant sulfur analog of murine selenium-glutathione peroxidase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 205:955-60. [PMID: 1577013 DOI: 10.1111/j.1432-1033.1992.tb16862.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We previously constructed plasmids for synthesis of glutathione-peroxidase (GPx) mutants in an Escherichia coli expression system. In these recombinant proteins either cysteine ([Cys]GPx mutant) or serine ([Ser]GPx mutant) were present in place of the active-site selenocysteine (SeCys) of the natural enzyme. We have now investigated GPx activity of [Cys]GPx and [Ser]GPx mutants. Enzyme assays performed on preparations of these partially purified proteins demonstrated that the [Cys]GPx mutant exhibited a significant GPx activity, unlike the [Ser]GPx mutant. Purification of [Cys]GPx was performed in two steps of ion-exchange chromatography giving a 98% homogenous protein in 50% yield. The purified [Cys]GPx protein was shown to be a symmetrical tetramer by the means of gel-filtration HPLC and SDS/PAGE. Two isoelectric points were found (6.8 and 7.2) which may reflect two different oxidation states of the mutant protein. The GPx activity of the [Cys]GPx mutant was optimal at pH 8.5. The [Cys]GPx mutant had a specific activity approximately 1000-fold smaller than that of the natural enzyme, and was very easily inactivated by hydroperoxides. Inhibition of the activity with iodoacetate determined a pKa of 8.3, presumably that of the active-site cysteine. Unlike that of SeGPx, the GPx activity of [Cys]GPx was only slightly inhibited by mercaptosuccinate. We discuss hypothetical mechanistic constraints of either catalytic cycle, which may explain such results.
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Affiliation(s)
- C Rocher
- Centre de Recherches Roussel-UCLAF, Romainville, France
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13
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Abstract
The increased activity of glutathione peroxidase (GSHPx) in rat lungs is associated with the development of tolerance of the animals to hyperoxia. To understand further the regulation of expression of this enzyme, the molecular structure of the corresponding rat gene was characterized. The rat GSHPx gene consists of two exons interrupted by a single intron of 217 base pairs. The same initiation sites for transcription were found to be utilized in both lung and liver. The promoter of the GSHPx gene contains neither a 'TATA' box nor a 'CAAT' box. Instead, it comprises two copies of Sp1 binding motif and one copy of AP-2 binding motif. These features of the promoter may offer a clue to the mechanisms by which the expression of this gene is controlled.
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Affiliation(s)
- Y S Ho
- Department of Medicine, Duke University Medical Center, Durham, NC 27710
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Vanha-Perttula T, Remes E. Incorporation of selenium-75 into seminal plasma and spermatozoa of the bull. Andrologia 1990; 22:34-41. [PMID: 2281876 DOI: 10.1111/j.1439-0272.1990.tb01937.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
75Se was given intravenously into 5 bulls. Multiple blood and semen samples were taken and during slaughter 5, 10, 15, 20 and 80 days later samples of various reproductive and other organs were collected. After injection, 75Se in blood reached a peak at 6 h followed by a rapid decline. The label was mainly found in serum with very low levels in erythrocytes. Initially the serum 75Se was bound to a macromolecule with a mw of 80 kDa, but later a larger molecule (100 kDa) was observed. In semen 75Se was first mainly found in seminal plasma, where a plateau level was reached at 5 d followed by a gradual decline after 12 d. The total semen level, however, increased after 14 d and this increase was due to a rapid appearance of the label in spermatozoa. The sperm 75Se level reached a plateau at 20 d and remained high until 40 days, after which a gradual decline ensued. The seminal plasma 75Se eluted in gel filtration coincident with glutathione peroxidase. The highest levels of 75Se were found in the kidney followed by seminal vesicles and testicles. The seminal vesicle secretion was particularly rich in 75Se and its fractionation resembled that of the seminal plasma. 75Se appeared in the epididymal caput within 5 days and passed through the epididymis in 20 days. It is concluded that 75Se is actively incorporated in the bull seminal vesicles into GSH-Px, while in the testis it is incorporated into a structural sperm protein during spermatogenesis.
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Affiliation(s)
- T Vanha-Perttula
- Department of Anatomy, Veterinary Research Station, University of Kuopio, Finland
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Viljoen AJ, Motchnik PA, Tappel AL. Selenium-containing proteins of rat kidney and liver microsomes. J Inorg Biochem 1989; 37:295-308. [PMID: 2628547 DOI: 10.1016/0162-0134(89)85004-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Selenium (Se)-containing proteins in microsomal fractions of rat kidney and liver were investigated after isotopic labeling of rats with [75Se]selenite. More than 85% of the 75Se in the solubilized microsomal extracts precipitated with protein after trichloroacetic acid treatment. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), used to separate the labeled protein subunits in the solubilized microsomal extracts, revealed several 75Se-containing proteins in addition to glutathione peroxidase. 75Se-labeled subunits with molecular weights of 55, 30, 26, 22, 19, and 17 kDa were present in microsomal fractions of kidney and liver. The 75Se-labeled tryptic peptide of the 55 kDa subunit had the same Rf value on a 17% SDS-PAGE gel as the peptide from plasma selenoprotein P. A time-course study of the labeling of individual protein subunits in kidney and liver microsomes from Se-supplemented and Se-deficient rats showed that most of the 75Se was associated with the 55 kDa subunit 3 hr after injection. The amount of 75Se associated with this protein subunit decreased by 12 hr, with a concurrent increase in the labeling of lower molecular-weight subunits. The results support the hypothesis that there is a mechanism for transfer of Se from the 55 kDa subunit to other Se-containing proteins.
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Affiliation(s)
- A J Viljoen
- Department of Food Science and Technology, University of California, Davis 95616
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Borglund M, Sjöblad S, Akesson B. Effect of selenium supplementation on the distribution of selenium among plasma proteins of a patient with maple syrup urine disease. Eur J Pediatr 1989; 148:767-9. [PMID: 2792131 DOI: 10.1007/bf00443107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Selenium (Se) status was studied in a patient with classical maple syrup urine disease (MSUD) receiving Se supplement. The basal plasma Se concentration was 0.06 mumol/l increasing to 2.1 mumol/l after 40 days of supplementation. When the plasma Se distribution was analysed by gel filtration, a major peak was seen close to the high molecular weight proteins with a second peak in the albumin region. When the Se dose was decreased in a stepwise manner from 50 micrograms/day to 25 micrograms/day and then to 17 micrograms/day plasma Se decreased, but the proportion of plasma Se in the two protein peaks did not change. In a healthy girl not supplemented with Se, the proportion of plasma Se in the albumin region was somewhat lower. In the MSUD patient glutathione peroxidase activity was initially low, and increased ten-fold during Se supplementation. The study indicates that the Se requirement for plasma glutathione peroxidase activity was fulfilled at the lowest dose of Se used and that Se is incorporated into several plasma proteins after supplementation.
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Affiliation(s)
- M Borglund
- Department of Clinical Chemistry, University of Lund, Sweden
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Fauque G, Peck HD, Moura JJ, Huynh BH, Berlier Y, DerVartanian DV, Teixeira M, Przybyla AE, Lespinat PA, Moura I. The three classes of hydrogenases from sulfate-reducing bacteria of the genus Desulfovibrio. FEMS Microbiol Rev 1988; 4:299-344. [PMID: 3078655 DOI: 10.1111/j.1574-6968.1988.tb02748.x] [Citation(s) in RCA: 163] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Three types of hydrogenases have been isolated from the sulfate-reducing bacteria of the genus Desulfovibrio. They differ in their subunit and metal compositions, physico-chemical characteristics, amino acid sequences, immunological reactivities, gene structures and their catalytic properties. Broadly, the hydrogenases can be considered as 'iron only' hydrogenases and nickel-containing hydrogenases. The iron-sulfur-containing hydrogenase ([Fe] hydrogenase) contains two ferredoxin-type (4Fe-4S) clusters and an atypical iron-sulfur center believed to be involved in the activation of H2. The [Fe] hydrogenase has the highest specific activity in the evolution and consumption of hydrogen and in the proton-deuterium exchange reaction and this enzyme is the most sensitive to CO and NO2-. It is not present in all species of Desulfovibrio. The nickel-(iron-sulfur)-containing hydrogenases [( NiFe] hydrogenases) possess two (4Fe-4S) centers and one (3Fe-xS) cluster in addition to nickel and have been found in all species of Desulfovibrio so far investigated. The redox active nickel is ligated by at least two cysteinyl thiolate residues and the [NiFe] hydrogenases are particularly resistant to inhibitors such as CO and NO2-. The genes encoding the large and small subunits of a periplasmic and a membrane-bound species of the [NiFe] hydrogenase have been cloned in Escherichia (E.) coli and sequenced. Their derived amino acid sequences exhibit a high degree of homology (70%); however, they show no obvious metal-binding sites or homology with the derived amino acid sequence of the [Fe] hydrogenase. The third class is represented by the nickel-(iron-sulfur)-selenium-containing hydrogenases [( NiFe-Se] hydrogenases) which contain nickel and selenium in equimolecular amounts plus (4Fe-4S) centers and are only found in some species of Desulfovibrio. The genes encoding the large and small subunits of the periplasmic hydrogenase from Desulfovibrio (D.) baculatus (DSM 1743) have been cloned in E. coli and sequenced. The derived amino acid sequence exhibits homology (40%) with the sequence of the [NiFe] hydrogenase and the carboxy-terminus of the gene for the large subunit contains a codon (TGA) for selenocysteine in a position homologous to a codon (TGC) for cysteine in the large subunit of the [NiFe] hydrogenase. EXAFS and EPR studies with the 77Se-enriched D. baculatus hydrogenase indicate that selenium is a ligand to nickel and suggest that the redox active nickel is ligated by at least two cysteinyl thiolate and one selenocysteine selenolate residues.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- G Fauque
- Section Enzymologie et Biochimie Bactérienne, ARBS, CEN Cadarache, Saint-Paul-Lez-Durance, France
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19
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Valle RP, Morch MD. Stop making sense: or Regulation at the level of termination in eukaryotic protein synthesis. FEBS Lett 1988; 235:1-15. [PMID: 3042454 PMCID: PMC7130263 DOI: 10.1016/0014-5793(88)81225-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/1988] [Indexed: 01/03/2023]
Abstract
An increasing number of examples of translational regulation at the level of termination has been recently reported in eukaryotes. This paper reviews our present knowledge on this topic and proposes an understanding of these regulations by relating the study of viral gene expression to a comprehensive view of the mechanisms and components of the translational process.
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Key Words
- viral gene expression
- nonsense suppression
- frameshift
- suppressor trna
- protein synthesis termination
- translational accuracy
- aids, acquired immunodeficiency syndrome
- almv, alfalfa mosaic virus
- blv, bovine leukemia virus
- bnyvv, beet necrotic yellow vein virus
- bp, base pair
- camv, cauliflower mosaic virus
- carmv, carnation mottle virus
- felv, feline leukemia virus
- hiv-1, human immunodeficiency virus type 1
- htlv i, human t-cell leukemia virus type i
- htlv ii, human t-cell leukemia virus type ii
- ibv, infectious bronchitis virus
- nt, nucleotide
- ltsv, lucerne transient streak virus
- mo-mulv, moloney murine leukemia virus
- mmtv, mouse mammary tumor virus
- mpmv, mason pfizer monkey virus
- orf, open reading frame
- p-ser, phosphoserine
- ramulv, rauscher murine leukemia virus
- rf, release factor
- rsv, rous sarcoma virus
- se-cys, selenocysteine
- tmv, tobacco mosaic virus
- trv, tobacco rattle virus
- tymv, turnip yellow mosaic virus
- sbwmv, soil-borne wheat mosaic virus
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Affiliation(s)
- R P Valle
- Institut Jacques Monod, Paris, France
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Reddy AP, Hsu BL, Reddy PS, Li NQ, Thyagaraju K, Reddy CC, Tam MF, Tu CP. Expression of glutathione peroxidase I gene in selenium-deficient rats. Nucleic Acids Res 1988; 16:5557-68. [PMID: 2838821 PMCID: PMC336784 DOI: 10.1093/nar/16.12.5557] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have characterized a cDNA pGPX1211 encoding rat glutathione peroxidase I. The selenocysteine in the protein corresponded to a TGA codon in the coding region of the cDNA, similar to earlier findings in mouse and human genes, and a gene encoding the formate dehydrogenase from E. coli, another selenoenzyme. The rat GSH peroxidase I has a calculated subunit molecular weight of 22,155 daltons and shares 95% and 86% sequence homology with the mouse and human subunits, respectively. The 3'-noncoding sequence (greater than 930 bp) in pGPX1211 is much longer than that of the human sequences. We found that glutathione peroxidase I mRNA, but not the polypeptide, was expressed under nutritional stress of selenium deficiency where no glutathione peroxidase I activity can be detected. The failure of detecting any apoprotein for the glutathione peroxidase I under selenium deficiency and results published from other laboratories supports the proposal that selenium may be incorporated into the glutathione peroxidase I co-translationally.
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Affiliation(s)
- A P Reddy
- Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802
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21
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Mizutani T, Hitaka T. The conversion of phosphoserine residues to selenocysteine residues on an opal suppressor tRNA and casein. FEBS Lett 1988; 232:243-8. [PMID: 2966747 DOI: 10.1016/0014-5793(88)80425-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This study has been undertaken in order to elucidate the mechanisms of incorporation of Se into glutathione peroxidase (GSHPx), in which selenocysteine corresponds to the opal termination codon UGA on the mRNA. We studied the above mechanisms using an opal suppressor tRNA, prepared from bovine liver, and casein as a model protein for the GSHPx apo-enzyme which might contain phosphoserine. The results showed that opal suppressor tRNA did not accept selenocysteine (lower than 0.1 mmol/mol) under the standard conditions. A trace amount of phosphoseryl-tRNA was converted to selenocysteyl-tRNA by incubation with H2Se and some enzymes. Meanwhile, a number of phosphoserine residues in casein were converted to selenocysteine residues by incubation with H2Se and enzymes. These results suggest that opal suppressor tRNA plays a role in synthesizing GSHPx via co- and/or post-translational mechanisms.
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Affiliation(s)
- T Mizutani
- Faculty of Pharmaceutical Sciences, Nagoya City University, Japan
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22
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A termination codon specifies selenocysteine in glutathione peroxidase. Nutr Rev 1988; 46:202-5. [PMID: 2967929 DOI: 10.1111/j.1753-4887.1988.tb05427.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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23
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Hu ML, Viljoen AJ, Tappel AL. Interactions of gold with cytosolic selenium-containing proteins in rat kidney and liver. J Inorg Biochem 1988; 32:281-90. [PMID: 3132529 DOI: 10.1016/0162-0134(88)85008-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Rats injected with aurothioglucose (ATG) for 5 days were subsequently injected with [75Se]selenious acid and killed after 3 days. Kidney and liver cytosols were chromatographed on Sephadex G-150. 75Se in kidney was associated with high molecular weight (HMW), 85,000 Mr, 26,000 Mr, and 10,000 Mr proteins and with a nonprotein fraction. The elution profile of liver cytosol was similar to that of kidney, but without a 26,000 Mr protein. ATG injection increased the association of 75Se with all fractions of kidney cytosol except the 85,000 Mr fractions, which contained Se-glutathione peroxidase (SeGSHPx) activity; 75Se in liver was increased only in HMW fractions. Unfractionated kidney cytosolic SeGSHPx activity was decreased 14% by ATG injection, but liver enzyme activity was not changed. However, Sephadex G-150 chromatography showed that total and specific activities, respectively, were decreased 28 and 23% in kidney and 25 and 16% in liver. Au coeluted with HMW and 10,000 Mr 73Se-containing kidney proteins; the latter contained 50% of the Au eluted from the column. DEAE Sephacel chromatography of the 10,000 Mr kidney protein showed that both Au and 75Se were tightly associated with metallothionein-like proteins. This study demonstrates the interaction of Au with rat liver and kidney 75Se-containing proteins.
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Affiliation(s)
- M L Hu
- Department of Food Science and Technology, University of California, Davis 95616
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24
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Incorporation of selenium into glutathione peroxidase. Nutr Rev 1987; 45:344-5. [PMID: 3141850 DOI: 10.1111/j.1753-4887.1987.tb00988.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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25
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Mullenbach GT, Tabrizi A, Irvine BD, Bell GI, Hallewell RA. Sequence of a cDNA coding for human glutathione peroxidase confirms TGA encodes active site selenocysteine. Nucleic Acids Res 1987; 15:5484. [PMID: 2955287 PMCID: PMC305979 DOI: 10.1093/nar/15.13.5484] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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26
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Chambers I, Harrison PR. A new puzzle in selenoprotein biosynthesis: selenocysteine seems to be encoded by the ‘stop’ codon, UGA. Trends Biochem Sci 1987. [DOI: 10.1016/0968-0004(87)90125-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Karle JA, Shrift A. Use of selenite, selenide, and selenocysteine for the synthesis of formate dehydrogenase by a cysteine-requiring mutant ofEscherichia coli K-12. Biol Trace Elem Res 1986; 11:27-35. [PMID: 24254500 DOI: 10.1007/bf02795520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/1986] [Accepted: 06/14/1986] [Indexed: 11/28/2022]
Abstract
The forms of Se in the Se-dependent enzyme formate dehydrogenase is known to be selenocysteine, but the way this amino acid enters the polypeptide chain has not been established. Through the use of a cysteine-requiring mutant ofEscherichia coli K-12 that could also grow in the presence of glutathione, we were able to study the effect of selenite, selenide, andL-selenocysteine, each at a concentration of 0.1 μM, on the synthesis of formate dehydrogenase. The three forms of Se served equally well for inducing formate dehydrogenase activity, measured by dichlorophenol-indophenol reduction mediated by phenazine methosulfate. It is known that selenite can be reduced to selenide by the action of glutathione reductase, present inE. coli, and that selenocysteine is converted to elemental Se by the action of selenocysteine lyase, also present in the mutant. Elemental Se is then reduced nonenzymatically to hydrogen selenide. The conversion of both selenite and selenocysteine to selenide and the ability of each form of Se to induce the synthesis of equal levels of formate dehydrogenase suggest that the incorporation of Se into formate dehydrogenase is accomplished by a posttranslational mechanism.
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Affiliation(s)
- J A Karle
- Department of Biological Sciences, State University of New York at Binghamton, 13901, Binghamton, NY
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28
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Takahashi K, Newburger PE, Cohen HJ. Glutathione peroxidase protein. Absence in selenium deficiency states and correlation with enzymatic activity. J Clin Invest 1986; 77:1402-4. [PMID: 3457020 PMCID: PMC424509 DOI: 10.1172/jci112449] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Glutathione peroxidase (GSHPx) activity is an indicator of selenium status in selenium-deficient individuals. Utilizing polyclonal monospecific antibodies to purified erythrocyte GSHPx, we were able to determine the relationship between enzymatic activity and protein content. In erythrocytes from a selenium-deficient individual who was treated with selenium, and in HL-60 cells grown in the absence of selenium and then returned to selenium-containing medium, there was a direct relationship between enzymatic activity and protein content. Thus, selenium deficiency results not only in a decrease of GSHPx activity, but also in a decrease of GSHPx protein.
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Wilhelmsen EC, Hawkes WC, Tappel AL. Substitution of selenocysteine for cysteine in a reticulocyte lysate protein synthesis system. Biol Trace Elem Res 1985; 7:141-51. [PMID: 24259116 DOI: 10.1007/bf02916536] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/1984] [Accepted: 11/20/1984] [Indexed: 12/01/2022]
Abstract
Selenocysteine occurs in the peptide backbone of several selenoenzymes. The mechanism, of selenocysteine incorporation has not been well characterized. The incorporation of selenocysteine into protein in a rabbit reticulocyte lysate (RRL) was studied at high levels of selenocysteine. [(75)Se]Selenocysteine incorporation was inhibited by cycloheximide and by nuclease treatment. Random RNA copolymers were tested for protein synthesis activity in the messenger RNA-dependent RRL system. Of the active polymers, poly CIU and GU most strongly stimulated the incorporation of selenocysteine. In a series of four polymers with different ratios of U to G, incorporation of selenocysteine and cysteine increased with increasing percentages of U, suggesting that selenocysteine and cysteine responded to the same codon, presumably UGU. Of the 20 protein amino acids, only cysteine and cystine competed with selenocysteine incorporation. Selenocysteine was charged to cysteine-accepting tRNA in RRL. These results show that at supraphysiological concentrations selenocysteine can substitute for cysteine in RRL protein synthesis. Misincorporation of selenocysteine could be important when animal tissues contain high levels of selenium.
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Affiliation(s)
- E C Wilhelmsen
- Department of Food Science and Technology, University of California, 95616, Davis, California
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30
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Hawkes WC, Wilhelmsen EC, Tappel AL. Abundance and tissue distribution of selenocysteine-containing proteins in the rat. J Inorg Biochem 1985; 23:77-92. [PMID: 3156209 DOI: 10.1016/0162-0134(85)83011-7] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The form and distribution of selenium (Se) in proteins from selected tissues of the rat were studied by measuring 75Se radioactivity in animals provided for 5 months with [75Se]selenite as the main dietary source of Se. Equilibration of the animals to a constant specific activity of 75Se allowed the measurement of 75Se to be used as a specific elemental assay for Se. Skeletal muscle, liver and blood accounted for 73% of the whole-body Se and 95% of the total Se-dependent glutathione peroxidase activity. Over 80% of the whole-body Se was in protein in the form of the selenoamino acid, selenocysteine. All other forms of Se that were measured accounted for less than 3% of the whole-body Se. The Se in protein was distributed in seven subunit sizes and nine chromatographic forms. The Se in glutathione peroxidase accounted for one-third of the whole-body Se. These results show that the main use of dietary Se, as selenite, in rats is for the synthesis of selenocysteine-containing proteins. Furthermore, the presence of two-thirds of the whole-body Se in nonglutathione peroxidase, selenocysteine-containing proteins suggests that there may be other important mammalian selenoenzymes besides glutathione peroxidase.
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Wilson MJ, Hatfield DL. Incorporation of modified amino acids into proteins in vivo. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 781:205-15. [PMID: 6367826 DOI: 10.1016/0167-4781(84)90085-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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33
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TAPPEL ALL. Selenium–Glutathione Peroxidase: Properties and Synthesis. CURRENT TOPICS IN CELLULAR REGULATION 1984. [DOI: 10.1016/b978-0-12-152824-9.50015-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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34
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Tappel AL, Hawkes WC, Wilhelmsen EC, Motsenbocker MA. Selenocysteine-containing proteins and glutathione peroxidase. Methods Enzymol 1984; 107:602-19. [PMID: 6239081 DOI: 10.1016/0076-6879(84)07044-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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36
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Hawkes WC, Tappel AL. In vitro synthesis of glutathione peroxidase from selenite. Translational incorporation of selenocysteine. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 739:225-34. [PMID: 6218828 DOI: 10.1016/0167-4781(83)90033-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The synthesis of glutathione peroxidase from [75Se]selenite was studied in slices and cell-free extracts from rat liver. The incorporation of [75Se]selenocysteine at the active site was detected by carboxymethylation and hydrolysis of partially purified glutathione peroxidase (glutathione:hydrogen peroxide oxidoreductase, EC 1.11.1.9) in the presence of [3H]selenocysteine and subsequent amino acid analysis. The synthesis of glutathione peroxidase in slices was inhibited by cycloheximide or puromycin and 75Se was incorporated from [75Se]selenite into free selenocysteine and selenocysteyl tRNA. Increasing concentrations of selenocystine caused a progressive dilution of the 75Se and a corresponding decrease in glutathione peroxidase labeling. In cell-free systems, [75Se]selenocysteyl tRNA was the best substrate for glutathione peroxidase synthesis. These results indicate the existence in rat liver of the de novo synthesis of free selenocysteine and a translational pathway of selenocysteine incorporation into glutathione peroxidase.
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