FIG. 4.
Activities of IsTRP and Grx5. (A) Insulin reduction by dithiothreitol. Twenty micromolars of IsTRP and Grx5; and 2 μM of a Trx from E. granulosus. The absorbance at 650 nm is plotted against time. (B) HED activity assay. The capacity of IsTRP, Grx5, and a Grx from E. granulosus to deglutathionylate was evaluated. NADPH oxidation was followed by measuring absorbance at 340 nm. The full time courses obtained are shown. (C) Reduction of 20 μM wild-type IsTRP (black) and mutants Cys to Ser by the TGRC31S (a TGR mutant that conserves full TR activity, but lacks gutathione reductase activity). One hundred twenty-five nanomolars of TGRC31S was used for the assay. Representative full time courses of NADPH oxidation are shown. TGR, thioredoxin glutathione reductase; TR, Thioredoxin reductase.