scholarly journals Thioredoxin Reductase Activity in Rat Liver Is Not Affected by Supranutritional Levels of Monomethylated Selenium In Vivo and Is Inhibited Only by High Levels of Selenium In Vitro

2001 ◽  
Vol 131 (2) ◽  
pp. 301-304 ◽  
Author(s):  
Howard E. Ganther ◽  
Clement Ip
2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Vasco Branco ◽  
Paula Ramos ◽  
João Canário ◽  
Jun Lu ◽  
Arne Holmgren ◽  
...  

Exposure to mercury is normally assessed by measuring its accumulation in hair, blood or urine. Currently, the biomarkers of effect that have been proposed for mercurials, such as coproporphyrines or oxidative stress markers, are not sensitive enough and lack specificity. Selenium and selenoproteins are important targets for mercury and thioredoxin reductase (TrxR) in particular was shown to be very sensitive to mercury compounds bothin vitroandin vivo. In this study we looked into the relation between the inhibition of thioredoxin reductase (TrxR) activity and histopathological changes caused by exposure to mercurials. Juvenile zeabra-seabreams were exposed to Hg2+or MeHg for 28 days and histopathological changes were analyzed in the liver and kidney as well as TrxR activity. Both mercurials caused histopathological changes in liver and kidney, albeit Hg2+caused more extensive and severe lesions. Likewise, both mercurials decreased TrxR activity, being Hg2+a stronger inhibitor. Co-exposure to Hg2+and Se fully prevented TrxR inhibition in the liver and reduced the severity of lesions in the organ. These results show that upon exposure to mercurials, histopathological alterations correlate with the level of TrxR activity and point to the potential use of this enzyme as a biomarker of mercury toxicity.


Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 913
Author(s):  
Jorge Guío ◽  
María Teresa Bes ◽  
Mónica Balsera ◽  
Laura Calvo-Begueria ◽  
Emma Sevilla ◽  
...  

FurA is a multifunctional regulator in cyanobacteria that contains five cysteines, four of them arranged into two CXXC motifs. Lack of a structural zinc ion enables FurA to develop disulfide reductase activity. In vivo, FurA displays several redox isoforms, and the oxidation state of its cysteines determines its activity as regulator and its ability to bind different metabolites. Because of the relationship between FurA and the control of genes involved in oxidative stress defense and photosynthetic metabolism, we sought to investigate the role of type m thioredoxin TrxA as a potential redox partner mediating dithiol-disulfide exchange reactions necessary to facilitate the interaction of FurA with its different ligands. Both in vitro cross-linking assays and in vivo two-hybrid studies confirmed the interaction between FurA and TrxA. Light to dark transitions resulted in reversible oxidation of a fraction of the regulator present in Anabaena sp. PCC7120. Reconstitution of an electron transport chain using E. coli NADPH-thioredoxin-reductase followed by alkylation of FurA reduced cysteines evidenced the ability of TrxA to reduce FurA. Furthermore, the use of site-directed mutants allowed us to propose a plausible mechanism for FurA reduction. These results point to TrxA as one of the redox partners that modulates FurA performance.


2008 ◽  
Vol 46 (01) ◽  
Author(s):  
F Moriconi ◽  
H Christiansen ◽  
H Christiansen ◽  
N Sheikh ◽  
J Dudas ◽  
...  

1975 ◽  
Vol 24 (4) ◽  
pp. 517-521 ◽  
Author(s):  
Gerard J. Mulder ◽  
Arnold H.E. Pilon
Keyword(s):  

1972 ◽  
Vol 126 (2) ◽  
pp. 347-350 ◽  
Author(s):  
A. A.-B. Badawy

1. Salicylate, in concentrations of 0.25mm and above, enhances the basal activity of tyrosine–2-oxoglutarate aminotransferase in homogenates of rat liver incubated in the absence of added pyridoxal 5′-phosphate (endogenous activity). The effect is decreased by increasing the concentration of the cofactor. 2. The intraperitoneal administration of sodium salicylate enhances the activity of rat liver tyrosine aminotransferase; the major effect during the first hour being on the enzyme in the absence of added pyridoxal phosphate. Actinomycin D prevents the induction of the enzyme by cortisol and tryptophan. Induction by pyridoxine or salicylate is 50% inhibited by actinomycin D. The effects of the injections of various combinations of cortisol, pyridoxine and salicylate were also studied in the absence or presence of actinomycin D. 3. It is suggested that salicylate induces rat liver tyrosine aminotransferase by displacing its protein-bound cofactor and that a cofactor-type induction of the hepatic enzyme occurs in pyridoxine-treated rats.


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