Molybdopterin

Molybdopterins are a class of biochemical cofactors that are used in many different enzymes. The simplest structure of molybdopterin contains a pyranopterin coordinated to molybdenum. The pyranopterin structure is a fused ring system containing a pyran fused to pterin. In addition, the pyran ring is substituted with two thiols and an alkyl phosphate. In molybdopterin, the thiols coordinate to molybdenum. In some cases, the alkyl phosphate group is replaced by an alkyl diphosphate nucleotide.

There are several enzymes whose function depends on the molybdopterin cofactor. Some of these include xanthine oxidase, DMSO reductase, sulfite oxidase, and nitrate reductase.

Some effort has been placed into modeling the active sites of enzymes like Molybdopterin using a class of ligands known as Dithiolenes.