The function of vitamin K largely depends on which mineral

The function of Vit K depends on Calcium. Function of vitamin K 1. Formation of g-carboxyglutamate (GLA): Vitamin K is required in the hepatic synthesis of prothrombin and blood clotting factors II, VII, IX, and X. These proteins are synthesized as inactive precursor molecules. Formation of the clotting factors requires the vitamin K-dependent carboxylation of glutamic acid residues to Gla residues (Figure 28.26). This forms a mature clotting factor that contains GLA and is capable of subsequent activation. The reaction requires O2, CO2, and the hydroquinone form of vitamin K. The formation of Gla is sensitive to inhibition by dicumarol, an anticoagulant occurring naturally in spoiled sweet clover, and by warfarin, a synthetic analog of vitamin K. 2. Interaction of prothrombin with platelets: The Gla residues of prothrombin are good chelators of positively charged calcium ions, because of the two adjacent, negatively charged carboxylate groups. The prothrombin-calcium complex is then able to bind to phospholipids essential for blood clotting on the surface of platelets. Attachment to the platelet increases the rate at which the proteolytic conversion of prothrombin to thrombin can occur (Figure 28.27). Reference: Lippincott Textbook of Biochemistry pg no.389