menaquinone-9

Menaquinone-9 (MK-9) is a long-chain vitamer of Vitamin K2, characterized by a side chain containing nine isoprene units. It is primarily synthesized by various bacterial species, including those found in the human intestinal microbiota and fermented dairy products such as certain types of cheese. Like other menaquinones, MK-9 serves as an essential lipid-soluble cofactor for the enzyme gamma-glutamyl carboxylase (GGCX). This enzyme facilitates the post-translational carboxylation of glutamate residues in vitamin K-dependent proteins (VKDPs), a process necessary for their biological activation. Key VKDPs activated by MK-9 include coagulation factors in the liver, osteocalcin in bone tissue, and matrix Gla protein (MGP) in the vascular system. Due to its longer prenyl side chain, MK-9 exhibits a significantly longer circulatory half-life compared to the short-chain MK-4, allowing for more sustained tissue distribution and potential long-term benefits for skeletal and cardiovascular health by promoting bone mineralization and inhibiting arterial calcification.

Other names

Vitamin K2(45)2-methyl-3-[(2E,6E,10E,14E,18E,22E,26E,30E)-3,7,11,15,19,23,27,31,35-nonamethylhexatriaconta-2,6,10,14,18,22,26,30,34-nonaenyl]naphthalene-1,4-dione2-methyl-3-all-trans-farnesylgeranylgeranyl-1,4-naphthoquinone