The Carboxylation of Preprothrombin

Vitamin K is a cofactor for the carboxylation of specific glutamic acid residues present in seven plasma proteins and in proteins in other tissues such as osteocalcin in bone. These glutamic acid residues are carboxylated on the y carbon and function as divalent metal binding sites, which are essential for the biological activity of these proteins. Much of the work on the mechanism of action of vitamin K has been done using prothrombin.