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Vitamin K epoxide reductase family in bacteria This family includes vitamin K epoxide reductase (VKOR) mostly present in actinobacteria. VKOR (also named VKORC1) is an integral membrane protein that catalyzes the reduction of vitamin K 2,3-epoxide and vitamin K to vitamin K hydroquinone, an essential co-factor subsequently used in the gamma-carboxylation of glutamic acid residues in blood coagulation enzymes. All homologs of VKOR contain an active site CXXC motif, which is switched between reduced and disulfide-bonded states during the reaction cycle. In some bacterial homologs, the VKOR domain is fused with domains of the thioredoxin family of oxidoreductases which may function as redox partners in initiating the reduction cascade.
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