Time courses of enzyme assays with the purified oxidoreductase. Assays were carried out independently to measure different components. (A) NADPH oxidation in an assay containing 1 mM U(VI), the purified oxidoreductase, thioredoxin reductase, thioredoxin, and NADPH (•). The final U(VI) concentration was 0.61 mM. Controls included only U(VI) in buffer (○) or U(VI) together with thioredoxin and thioredoxin reductase (▪). (B) U(VI) reduction in an assay containing 1 mM U(VI), the purified oxidoreductase, thioredoxin reductase, thioredoxin, and NADPH (▴), or in assays lacking the oxidoreductase (Δ) or thioredoxin (○). (C) NADPH oxidation in an assay with 1 mM Cr(VI), the purified oxidoreductase, thioredoxin reductase, thioredoxin, and NADPH (•) or in an assay mixture lacking thioredoxin and thioredoxin reductase (○) or Cr(VI) (▪).