Vitamin K epoxide reductase

Vitamin K epoxide reductase (VKOR) is an enzyme (EC 1.1.4.1) that reduces vitamin K after it has been oxidised in the carboxylation of glutamic acid residues in blood coagulation enzymes. VKORC is a member of a large family of predicted enzymes that are present in vertebrates, Drosophila, plants, bacteria and archaea. Its C1 subunit (VKORC1) is the target of anticoagulant warfarin. Four cysteine residues and one residue, which is either serine or threonine, are identified as likely active-site residues. In some plant and bacterial homologues, the VKORC1 homologous domain is fused with domains of the thioredoxin family of oxidoreductases.