Which molecule acts as a natural inhibitor of plasmin?

Which molecule acts as a natural inhibitor of plasmin?

• A. Tissue factor
• B. Alpha 2 Antiplasmin
• C. Thrombin
• D. Plasmin

Answer: (B)

Plasmin activity is tightly regulated to prevent accidental breakdown of clots. The main natural inhibitor in blood is alpha-2 antiplasmin, which rapidly binds active plasmin in circulation and at the clot, forming a stable complex that neutralizes plasmin’s proteolytic activity. This rapid inhibition helps maintain the balance between clot stability and dissolution. Tissue factor starts coagulation, thrombin drives clot formation, and plasmin is the enzyme that dissolves clots, not an inhibitor, so they don’t fit as the natural brake on plasmin.

Plasmin activity is tightly regulated to prevent accidental breakdown of clots. The main natural inhibitor in blood is alpha-2 antiplasmin, which rapidly binds active plasmin in circulation and at the clot, forming a stable complex that neutralizes plasmin’s proteolytic activity. This rapid inhibition helps maintain the balance between clot stability and dissolution. Tissue factor starts coagulation, thrombin drives clot formation, and plasmin is the enzyme that dissolves clots, not an inhibitor, so they don’t fit as the natural brake on plasmin.