Thioredoxin

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Thioredoxins are proteins that act as antioxidants by facilitating the reduction of other proteins by cysteine thiol-disulfide exchange. Thioredoxins are found in nearly all known organisms and are essential for life in mammals.^[1]^[2]

Thioredoxins are characterized at the level of their amino acid sequence by the presence of two vicinal cysteines in a CXXC motif. These two cysteines are the key to the ability of thioredoxin to reduce other proteins. Thioredoxin proteins also have a characteristic tertiary structure termed the thioredoxin fold.

The thioredoxins are kept in the reduced state by the flavoenzyme thioredoxin reductase, in a NADPH-dependent reaction.^[3] Thioredoxins act as electron donors to peroxidases and ribonucleotide reductase.^[4] The related glutaredoxins share many of the functions of thioredoxins, but are reduced by glutathione rather than a specific reductase.

[edit] See also

RuBisCO - enzyme activity regulated by thioredoxin

[edit] References

^ Holmgren A (1989). "Thioredoxin and glutaredoxin systems". J Biol Chem 264 (24): 13963-6. PMID 2668278.
^ Nordberg J, Arnér E (2001). "Reactive oxygen species, antioxidants, and the mammalian thioredoxin system". Free Radic Biol Med 31 (11): 1287-312. PMID 11728801.
^ Mustacich D, Powis G. "Thioredoxin reductase". Biochem J 346 Pt 1: 1-8. PMID 10657232.
^ Arnér E, Holmgren A (2000). "Physiological functions of thioredoxin and thioredoxin reductase". Eur J Biochem 267 (20): 6102-9. PMID 11012661.