Français
Albanian
Arabic
Armenian
Azerbaijani
Belarusian
Bengali
Bosnian
Catalan
Czech
Danish
Deutsch
Dutch
English
Estonian
Finnish
Français
Greek
Haitian Creole
Hebrew
Hindi
Hungarian
Icelandic
Indonesian
Irish
Italian
Japanese
Korean
Latvian
Lithuanian
Macedonian
Mongolian
Norwegian
Persian
Polish
Portuguese
Romanian
Russian
Serbian
Slovak
Slovenian
Spanish
Swahili
Swedish
Turkish
Ukrainian
Vietnamese
Български
中文(简体)
中文(繁體)
Proceedings of the National Academy of Sciences of the United States of America 1997-Apr

The mechanism of thioredoxin reductase from human placenta is similar to the mechanisms of lipoamide dehydrogenase and glutathione reductase and is distinct from the mechanism of thioredoxin reductase from Escherichia coli.

Seuls les utilisateurs enregistrés peuvent traduire des articles
Se connecter S'inscrire
Le lien est enregistré dans le presse-papiers
L D Arscott
S Gromer
R H Schirmer
K Becker
C H Williams

Mots clés

Abstrait

Thioredoxin reductase, lipoamide dehydrogenase, and glutathione reductase are members of the pyridine nucleotide-disulfide oxidoreductase family of dimeric flavoenzymes. The mechanisms and structures of lipoamide dehydrogenase and glutathione reductase are alike irrespective of the source (subunit M(r) approximately 55,000). Although the mechanism and structure of thioredoxin reductase from Escherichia coli are distinct (M(r) approximately 35,000), this enzyme must be placed in the same family because there are significant amino acid sequence similarities with the other two enzymes, the presence of a redox-active disulfide, and the substrate specificities. Thioredoxin reductase from higher eukaryotes on the other hand has a M(r) of approximately 55,000 [Luthman, M. & Holmgren, A. (1982) Biochemistry 21, 6628-6633; Gasdaska, P. Y., Gasdaska, J. R., Cochran, S. & Powis, G. (1995) FEBS Lett 373, 5-9; Gladyshev, V. N., Jeang, K. T. & Stadtman, T.C. (1996) Proc. Natl. Acad. Sci. USA 93, 6146-6151]. Thus, the evolution of this family is highly unusual. The mechanism of thioredoxin reductase from higher eukaryotes is not known. As reported here, thioredoxin reductase from human placenta reacts with only a single molecule of NADPH, which leads to a stable intermediate similar to that observed in titrations of lipoamide dehydrogenase or glutathione reductase. Titration of thioredoxin reductase from human placenta with dithionite takes place in two spectral phases: formation of a thiolate-flavin charge transfer complex followed by reduction of the flavin, just as with lipoamide dehydrogenase or glutathione reductase. The first phase requires more than one equivalent of dithionite. This suggests that the penultimate selenocysteine [Tamura, T. & Stadtman, T.C. (1996) Proc. Natl. Acad. Sci. USA 93, 1006-1011] is in redox communication with the active site disulfide/dithiol. Nitrosoureas of the carmustine type inhibit only the NADPH reduced form of human thioredoxin reductase. These compounds are widely used as cytostatic agents, so this enzyme should be studied as a target in cancer chemotherapy. In conclusion, three lines of evidence indicate that the mechanism of human thioredoxin reductase is like the mechanisms of lipoamide dehydrogenase and glutathione reductase and differs fundamentally from the mechanism of E. coli thioredoxin reductase.

Rejoignez notre
page facebook

La base de données d'herbes médicinales la plus complète soutenue par la science

  • Fonctionne en 55 langues
  • Cures à base de plantes soutenues par la science
  • Reconnaissance des herbes par image
  • Carte GPS interactive - étiquetez les herbes sur place (à venir)
  • Lisez les publications scientifiques liées à votre recherche
  • Rechercher les herbes médicinales par leurs effets
  • Organisez vos intérêts et restez à jour avec les nouvelles recherches, essais cliniques et brevets

Tapez un symptôme ou une maladie et lisez des informations sur les herbes qui pourraient aider, tapez une herbe et voyez les maladies et symptômes contre lesquels elle est utilisée.
* Toutes les informations sont basées sur des recherches scientifiques publiées

Google Play badgeApp Store badge