Claim: The sulfiredoxin enzyme (which does not have any substrates) belongs to the family of oxidoreductases which acts on a sulfur group of donors, and is involved in antioxidant metabolism by re-activating peroxiredoxins when they are inhibited by over-oxidation.
Evidence: The 3 substrates of this enzyme are peroxiredoxin-(S-hydroxy-S-oxocysteine), ATP, and a thiol, whereas its 4 products are peroxiredoxin-(S-hydroxycysteine), ADP, phosphate, and a disulfide.