CHEMBL3705973

In vitro Assay: The method of determining thioredoxin activity is based on the reduction of insulin by thioredoxin. Thioredoxin is reconstituted is by thioredoxin reductase, with NADPH. The resulting free thiol -SH groups react with 5,5′-dithiobis-2-nitrobenzoic acid (DTNB). The termination of the reaction results in the formation of a red colour. The intensity of colouration is determined spectrophotometrically at 412 nm and this corresponds to the number of reduced sulfahydryl groups. The reaction was performed at 37° C. over 30 min. in a buffer containing 50 mM Tris-HCl and 20 mM EDTA at a pH of 7.6. The substrate concentrations used were: 0.25 μM human recombinant thioredoxin and 0.325 μM rat recombinant thioredoxin reductase (IMCO Corporation Ltd AB, Sweden) and 316 μM of insulin, 0.8 μM NADPH, 8 mM DTNB (Sigma Aldrich).