Inhibition of Factor Xa in Prothrombinase Is Enhanced by Covalent Linkage of Antithrombin to Heparin.

Abstract Prothrombinase is the surface-bound complex in which factor Xa (Xa) converts prothrombin to thrombin in vivo. Studies have shown that Xa within prothrombinase is resistant to inhibition by antithrombin + heparin (AT+H). Previously we found that, unlike AT+H, a covalent conjugate of AT and H (ATH) was able to neutralize fibrin-bound thrombin. In this study, AT+H and ATH were compared in their reaction with Xa in …