Human GLRX2 Recombinant Protein. Glutaredoxin (Grx), also known as thiol transferase, is a small heat-stable oxidoreductase. Grxs form part of the glutaredoxin system, comprising NADPH, GSH and glutathione reductase, which transfers electrons from NADPH to glutaredoxins via GSH. First discovered in E. coli as GSH-dependent hydrogen donors for ribonucleotide reductase, Grx catalyzes GSH-disulfide oxidoreductase via two redox-active cysteine residues. The active sequence (Cys-Pro-Tyr-Cys) is conserved in a variety of species. The 12-kD dithiol protein has a role in reduction of mixed disulfides in cells exposed to oxidative stress.