This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins, Subject name: Biochemistry
The role of vitamin K in epoxide cycle is - 
Select and explain. 
A. Carboxylation of aspartate, B. Dehydrogenation of glucatamate, C. Carboxylation of glutamate, D. Dehydrogenation of aspartate
C: Carboxylation of glutamate
Answer: C: Carboxylation of glutamate 
Explanation: Ans. is 'c' i.e., Carboxylation of glutamate o The only known biological role of vitamin K is as a cofactor for an enzyme carboxylase that catalyzes carboxylationQ of glutamic acid (glutamate )Q residues on vitamin K-dependent proteins. The important vitamin K dependent proteins are ; -i) Coagulation proteins: - Factor IIQ (prothrombinQ), factor VIIQ (proconvertin0), factor IXQ (christmas factor), and factor XQ (Stuart-Prower factor),ii) Anticoagulation proteins : - Proteins Q S and Z.iii) Gas 6