Cysteine Dioxygenase I (CDO1)

Cysteine dioxygenase (CDO) is a mammalian non-heme iron enzyme that catalyzes the conversion of L-cysteine to cysteine sulfinic acid (cysteine sulfinate) by incorporation of dioxygen.The first step in the oxidation of cysteine to inorganic sulfate is its conversion to cysteine sulphinate by cysteine dioxygenase (CDO).

In rat, at least 2 enzymes catalyze this reaction, one cytosolic (CDO-I) and the other membrane-bound. Rat liver CDO contains 1 atom of iron per molecule of protein, and the enzyme is activated by anaerobic incubation with either L-cysteine or its analogs. The predicted 200-amino acid human and rat proteins are 94% identical. Northern blot analysis revealed that CDO-I is expressed as an approximately 1.5-kb mRNA in liver.