The Thioredoxin Assay is a solid-phase sandwich ELISA that uses two highly specific antibodies to human thioredoxin protein; one antibody is precoated onto the thioredoxin ELISA plate and the other antibody is HRP-conjugated. The thioredoxin assay can be used to measure soluble human thioredoxin protein in serum, EDTA-plasma, urine or cell culture supernatant.
Thioredoxins are a class of redox proteins found in all organisms. In humans, two isoforms of thioredoxin are encoded by the TXN gene. Thioredoxin is also known as surface-associated sulphydryl protein (SASP), ATL-derived factor (ADF), TRX, TRDX and TRX1. Thioredoxins are characterized by the presence of two neighboring cysteines arranged in a CXXC motif at the active site. Thioredoxins are maintained in the reduced state by the flavoenzyme thioredoxin reductase through an NADPH-dependent reaction. Thioredoxins act as electron donors to peroxidases and ribonucleotide reductase. Several transcription factors, such as NF-kappa B and AP1, also require thioredoxin-mediated reduction to exert DNA-binding activity. Thioredoxin knockout mammal embryos die in utero. Numerous other functions for thioredoxin have been described, including oxidative stress protection and control of growth and apoptosis.