What is the mechanism of heparin's anticoagulant action?
Heparin binds to positively charged residues on AT, producing a conformational change at the AT arginine reactive center that converts AT from a slow to a rapid inhibitor of serine proteases. The arginine reactive center on AT binds covalently to the active center serine of thrombin and other coagulation enzymes, thereby irreversibly inhibiting their procoagulant activity. Heparin then dissociates from AT and is reused.