Vitamin K

Literature References: General term referring to a group of naphthoquinone derivatives required for the bioactivation of proteins involved in hemostasis. The designation "K" was derived from the German "Koagulationsvitamin." Vitamin K compds are classified into 3 groups: phylloquinone (K1), q.v., found in green plants; menaquinones (K2), q.v., primarily produced by intestinal bacteria; and menadione (K3), q.v., and derivatives which are synthetic, lipid soluble compounds. Reduced in vivo to dihydrovitamin K (KH2) which serves as a coenzyme in the conversion of glutamic acid residues to g-carboxyglutamic acid (Gla), q.v., in the post-translational modification of blood coagulation factors II, VII, IX and X, and the anticoagulant proteins C and S. Other Gla-containing proteins, such as the bone matrix protein, osteocalcin, q.v., have been identified in a wide variety of tissues. This g-carboxylation is accompanied by the oxidation of KH2 to vitamin K epoxide which is then recycled back to vitamin K. Discovery: H. Dam, Biochem. Z. 215, 475 (1929); 220, 158 (1930); Nature 135, 652 (1935). Historical survey: H. Dam, Vitam. Horm. 24, 295-306 (1966). Menadione and phylloquinone are metabolized by animals to menaquinone-4: C. Martius, H. O. Esser, Biochem. Z. 331, 1 (1958); H. H. W. Thijssen, M. J. Drittij-Reijnders, Br. J. Nutr. 72, 415 (1994). HPLC determn in plasma: M. Kamao et al., J. Chromatogr. B 816, 41 (2005). Comprehensive review: W. Friedrich in Vitamins (de Gruyter, New York, 1988) pp 285-338. Review of metabolism and role in human nutrition: M. J. Shearer, Blood Rev. 6, 92-104 (1992); J. W. Suttie, J. Am. Diet. Assoc. 92, 585-590 (1992); of mechanism of action: P. Dowd et al., Nat. Prod. Rep. 11, 251-264 (1994); of pharmacology and therapeutic use: J. A. Thorp et al., Drugs 49, 376-387 (1995). Physiological review: M. J. Shearer, Lancet 345, 229-234 (1995).