Antithrombin-III-Hamilton, Ala 382 to Thr: An Antithrombin-III Variant That Acts as a Substrate But Not an Inhibitor of α-Thrombin and Factor Xa

Abstract Antithrombin-III-Hamilton has been shown to be a structural variant of antithrombin-III (AT-III) with normal heparin affinity but impaired protease inhibitory activity. The molecular defect of AT-III-Hamilton is the substitution of Thr for Ala at amino acid residue 382. The plasma of affected individuals contains approximately equal quantities of normal AT-III and AT-III-Hamilton. When AT-III was isolated from the …