Sulfiredoxin

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Sulfiredoxin is an enzyme that helps cells fight oxidative stress by reactivating peroxiredoxins, a family of antioxidant enzymes that neutralize peroxides. When peroxiredoxins become over-oxidized, they stop working. Sulfiredoxin uses ATP and a thiol to repair them, restoring peroxiredoxin activity. The reaction produces ADP, phosphate, and a disulfide as byproducts.

Sulfiredoxin belongs to the oxidoreductase family and acts on sulfur-containing donors. It was first discovered in yeast and is conserved in all eukaryotes, including humans. It is also known as Srxn1 or sulphiredoxin; in some mouse studies the gene was labeled Neoplastic progression 3 (Npn3), which has caused naming confusion.

In addition to reactivating peroxiredoxins, sulfiredoxin may help resolve mixed disulfide bonds in proteins. The full function is still being studied, but it clearly contributes to antioxidant defense.

In mice lacking sulfiredoxin, animals appear normal under baseline conditions, but after exposure to carcinogens they are less prone to certain cancers, suggesting sulfiredoxin can influence cancer development.