Submitted to: Advances in Nutrition
Publication Type: Review article
Publication Acceptance Date: 8/1/2011
Publication Date: 9/1/2011
Citation: Suttie, J., Booth, S.L. 2011. Vitamin K. Advances in Nutrition. 2:440-441. Interpretive Summary:
Technical Abstract: Vitamin K was identified in the early 1930’s when it was shown to be essential for normal blood coagulation. Phylloquinone (2-methyl-3-phytyl-1,4-naphthoquinone) found in green plants is the major source of the vitamin. Large amounts of menaquinones with lengthy side chains are also synthesized in the lower bowel by anaerobic bacteria, but only small amounts are absorbed. The metabolic role of vitamin K is as a substrate for an enzyme, the vitamin K-dependent carboxylase, that converts specific glutamic acid residues of a limited number of proteins to gamma-carboxyglutamic acid (Gla) residues by the addition of a carbon dioxide. This modification was first identified in the procoagulant protein prothrombin and subsequently in other plasma procoagulants. A small number of Gla-containing proteins have also been discovered in proteins other than those involved in blood coagulation, and their role in skeletal and tissue calcification is an active area of research. Gla-containing proteins have also been found in fish, snake and snail venoms, and invertebrates.