Cranenburg Ellen C M, Schurgers Leon J, Vermeer Cees
Department of Biochemistry, University of Maastricht, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
Thromb Haemost. 2007 Jul;98(1):120-5.
Vitamin K, discovered in the 1930s, functions as cofactor for the posttranslational carboxylation of glutamate residues. Gammacarboxy glutamic acid (Gla)-residues were first identified in prothrombin and coagulation factors in the 1970s; subsequently, extra-hepatic Gla proteins were described, including osteocalcin and matrix Gla protein (MGP). Impairment of the function of osteocalcin and MGP due to incomplete carboxylation results in an increased risk for developing osteoporosis and vascular calcification, respectively, and is an unexpected side effect of treatment with oral anticoagulants. It is conceivable that other side effects, possible involving growth-arrest-specific gene 6 (Gas6) protein will be identified in forthcoming years. In healthy individuals, substantial fractions of osteocalcin and MGP circulate as incompletely carboxylated species, indicating that the majority of these individuals is subclinically vitamin K-deficient. Potential new application areas for vitamin K are therefore its use in dietary supplements and functional foods for healthy individuals to prevent bone and vascular disease, as well as for patients on oral anticoagulant treatment to offer them protection against coumarin-induced side effects and to reduce diet-induced fluctuations in their INR values.
维生素K于20世纪30年代被发现，作为谷氨酸残基翻译后羧化作用的辅因子发挥功能。γ-羧基谷氨酸（Gla）残基于20世纪70年代首次在凝血酶原和凝血因子中被鉴定出来；随后，肝外Gla蛋白被描述，包括骨钙素和基质Gla蛋白（MGP）。由于羧化不完全导致骨钙素和MGP功能受损，分别会增加患骨质疏松症和血管钙化的风险，这是口服抗凝剂治疗的意外副作用。可以想象，未来几年可能会发现其他副作用，可能涉及生长停滞特异性基因6（Gas6）蛋白。在健康个体中，相当一部分骨钙素和MGP以羧化不完全的形式循环，这表明这些个体中的大多数存在亚临床维生素K缺乏。因此，维生素K的潜在新应用领域包括用于健康个体的膳食补充剂和功能性食品，以预防骨骼和血管疾病，以及用于口服抗凝剂治疗的患者，为他们提供保护，防止香豆素引起的副作用，并减少饮食引起的国际标准化比值（INR）波动。
