The assay measures the ability of the selenoprotein thioredoxin reductase to reduce substrates, including ribonucleotide reductase and peroxiredoxins, using NADPH and thioredoxin. It also tests for potential inhibitors and substrates of thioredoxin reductase using a fluorescence-based method. The assay is focused on validating the use of the assay for finding potential inhibitors and substrates of thioredoxin reductase. Is the molecule effective to this assay?