What are the mechanisms involved in heparin/AT complex inactivation of thrombin?
The heparin/AT complex inactivates thrombin (factor IIa) and factors Xa, IXa, XIa, and XIIa.5 Heparin catalyzes AT-mediated thrombin inhibition in a nonspecific charge-dependent fashion to form a ternary heparin/AT/thrombin complex. In contrast, to catalyze factor Xa inhibition by AT, heparin needs only to bind to AT.14 In both cases binding occurs at the unique pentasaccharide sequence found within some heparin molecules.