Thioredoxin reductase peptide, corresponding to residues 53–67 in thioredoxin reductase (TrxR), is used in thioredoxin reductase research. Mammalian thioredoxin reductase (TR) catalyzes the reduction of the redox-active disulfide bond of thioredoxin (Trx) and is essential for cellular redox homeostasis.