Question

Vitamin-K is required for

• A. Regulation of calcium and potassium metabolism
• B. Respiration
• C. Carbohydrate metabolism
• D. Synthesis of prothrombin in liver required for blood clotting

Answer 1

The correct option is D Synthesis of prothrombin in liver required for blood clotting

Six proteins involved in blood coagulation require vitamin K for their complete synthesis: factor IX, factor X, prothrombin, factor VII, protein C, and protein S. In the rough endoplasmic reticulum, specific glutamic acid residues in the protein are changed by an enzyme-mediated reaction to form a modified glutamic acid known as -carboxyglutamic acid. This enzyme reaction, known as -carboxylation, requires vitamin K as a cofactor.