Sulfite Oxidase (SUOX)

Sulfite oxidase (EC 1.8.3.1) is an enzyme in the mitochondria of all eukaryotes. It oxidizes sulfite to sulfate and, via cytochrome c, transfers the electrons produced to the electron transport chain, allowing generation of ATP in oxidative phosphorylation. This is the last step in the metabolism of sulfur-containing compounds and the sulfate is excreted.

Sulfite oxidase is a metallo-enzyme that utilizes a molybdopterin cofactor and a heme group. It is one of the cytochromes b₅ and belongs to the enzyme super-family of oxotransferases that also includes DMSO reductase, xanthine oxidase, and nitrite reductase.In mammals, the expression levels of sulfite oxidase is high in the liver, kidney, and heart, and very low in spleen, brain, skeletal muscle, and blood.