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T7915 Sigma

Thioredoxin Reductase from Escherichia coli

ammonium sulfate suspension, >25 units/mg protein (Bradford)

Synonym: NADPH:oxidized thioredoxin oxidoreductase



Biochem/physiol Actions

Thioredoxin reductase (TrxR) is an NADPH-dependent oxidoreductase containing one FAD per subunit that reduces the active site disulfide in oxidised thioredoxin (Trx). The molecular weight of the isozymes from mammalian sources vary between 55-67 kDa as compared with 35 kDa in prokaryotes, plants or yeast. The substrate specificity of the mammalian enzyme is much broader than the prokaryotic enzyme reducing both mammalian and E. coli thioredoxins as well as well as non-disulfide substrates such selenite, lipoic acids, lipid hydroperoxides and hydrogen peroxide.

An FAD-containing enzyme involved in the transfer of hydrogen from E. coli thioredoxin to other proteins thus providing a powerful disulfide reductase system.

Thioredoxin reductase is a FAD containing enzyme, which transfers the reducing equivalent from NADPH to the disulphide bond of the enzyme by using FAD moiety within the Cys-Ala-Thr-Cys sequence. It can also reduce Trx-S2 to Trx-(SH)2 by using NADPH.


250 μg in poly bottle

Unit Definition

One unit will cause an increase in absorbance of 1.0 at 412 nm (when measured in a coupled assay with E. coli thioredoxin and DTNB) per min per mL at pH 7.0 at 25 °C.

Physical form

Suspension in 3.6 M (NH4)2SO4 containing 30 mM potassium phosphate buffer, pH 7.5, and 2 mM EDTA.


Thioredoxin Reductase from Escherichia coli can be used in peroxidase-coupled thioredoxin system assay for assessing the peroxidase activitiy of Cys-based thiol peroxidases. The product was used for determining the enzymatic activity of His6-Ahp1p.

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Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 
Protocols & Articles


Ammonium Sulfate Suspensions - Technical Note

Note that for an ammonium sulfate suspension, most of the enzyme will be in solid form. It is likely that only negligible amounts of enzyme will be in the ammonium sulfate solution.
Keywords: Enzyme activity

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