Vitamin K is a fat-soluble vitamin whose essential biochemical function is serving as a cofactor for glutamate carboxylase, an enzyme that adds a carboxyl group to glutamate side chains (producing gamma-carboxyglutamate) on target proteins, enabling those proteins to bind calcium. This carboxylation reaction underlies vitamin K's dual physiological role in blood clotting (activating clotting factors II, VII, IX, X, and anticoagulant proteins C and S) and bone mineralization (activating osteocalcin, matrix Gla protein, and periostin). During catalysis vitamin K is oxidized to vitamin K epoxide and must be regenerated by vitamin K epoxide reductase, the enzyme pharmacologically inhibited by the anticoagulant warfarin — placing this concept within biochemistry's vitamin/cofactor metabolism and its intersection with clinical hemostasis.
Vitamin K is a fat-soluble vitamin whose essential biochemical function is serving as a cofactor for glutamate carboxylase, an enzyme that adds a carboxyl group to glutamate side chains (producing ga…