Purified Radiolabeled Antithrombin III Metabolism in Three Families With Hereditary AT Ill Deficiency: Application of a Three-Compartment Model

was used to study its metabolism in six members from three different families with a known hereditary AT Ill deficiency. Six healthy volunteers served as a control group. Sodium dodecyl sulfate-polyacrylamide gel electro-phoresis (SDS-PAGE) and crossed immunoelectrophoresis (CIE) showed the purified AT Ill to be homogenous. Amino acid analysis of the protein revealed a composition identi-cal to a highly purified internal standard. The specific activity was 5.6 U/mg. Analysis of plasma radioactivity data was performed, using a three-compartment model. Neither plasma disappearance half-times nor fractional A NTITHROMBIN III (AT III) has been shown to be a major inhibitor of activated senine proteases.”2 A high incidence of thromboembolic disease has been recognized in individuals with a hereditary deficiency of this inhibitor