Molybdenum cofactor

Molybdenum cofactor is a cofactor required for the activity of enzymes such as sulfite oxidase, xanthine oxidoreductase, and aldehyde oxidase. It is a coordination complex formed between molybdopterin (which, despite the name, does not contain molybdenum) and an oxide of molybdenum.

Molydopterins, in turn, are synthesized from guanosine triphosphate (see synthetic route at right).

Molybdenum cofactor functions directly in ethylbenzene dehydrogenase, glyceraldehyde-3-phosphate ferredoxin oxidoreductase, and respiratory arsenate reductase

In animals and plants these enzymes use molybdenum bound at the active site in a tricyclic molybdenum cofactor. All molybdenum-using enzymes so far identified in nature use this cofactor, save for the phylogenetically ancient molybdenum nitrogenases, which fix nitrogen in some bacteria and cyanobacteria. Molybdenum enzymes in plants and animals catalyze the oxidation and sometimes reduction of certain small molecules, as part of the regulation of nitrogen, sulfur and carbon cycles.