Menaquinone 9 (MK-9) is a vitamin K2 analog that has been found in various bacteria, including E. coli. MK-9 is UV-sensitive and binds to soluble nitrate reductase, a component of the bacterial electron transport chain. In vivo, MK-9 increases plasma prothrombin concentration in vitamin K-deficient rats.
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Vitamin (prothrombogenic).
Menaquinones are isoprenoid quinones of the naphthalene series and belongs to the K2 Vitamin homologs. Menaquinones were originally discovered as the anti-hemorrhagic factor and now encompasses a variety of physiological processes. Menaquinone 9 is a form of vitamin K2 which acts as a prothrombogenic agent and is also a functional electron transfer component in nitrate reductase.
ChEBI: Menaquinone-9 is a menaquinone whose side-chain contains 9 isoprene units in an all-trans-configuration. It has a role as an Escherichia coli metabolite.
[1] A.M CRāCIUN . Induction of prothrombin synthesis by K-vitamins compared in vitamin K-deficient and in brodifacoum-treated rats[J]. Biochimica et biophysica acta. General subjects, 1998, 1380 1: Pages 75-81. DOI:
10.1016/s0304-4165(97)00134-7[2] F BRITO M D J A DeMoss. Isolation and identification of menaquinone-9 from purified nitrate reductase of Escherichia coli.[J]. Journal of Bacteriology, 1995, 177 13: 3728-3735. DOI:
10.1128/jb.177.13.3728-3735.1995
