Question

Which of the following anticoagulants acts by inhibiting the γ-carboxylation of glutamate residues in clotting factors?

• A. Heparin
• B. Rivaroxaban
• C. Dabigatran
• D. Warfarin

Hint:

Several clotting factors (II, VII, IX and X) only work after their glutamate residues are γ-carboxylated, a reaction that needs vitamin K. Blocking vitamin K therefore stops these factors from working.

Answer 1

The Correct Option is D

Concept:
Several clotting factors (II, VII, IX and X) only work after their glutamate residues are γ-carboxylated, a reaction that needs vitamin K. Blocking vitamin K therefore stops these factors from working.

Step 1: Warfarin inhibits the enzyme vitamin K epoxide reductase, so the body cannot recycle vitamin K back to its active form.

Step 2: Without active vitamin K, the γ-carboxylation of glutamate residues cannot happen, and the clotting factors are produced in a non-functional form. This is exactly the mechanism described in the question.

Why the others are wrong: Heparin works by boosting antithrombin. Rivaroxaban is a direct factor Xa inhibitor, and dabigatran is a direct thrombin (factor IIa) inhibitor. None of these touch the vitamin-K-dependent carboxylation step — only warfarin does.

Answer: Option (4) — Warfarin.