title: Comparison of the kinetic behavior of human and bovine proteins in the heparin-catalyzed antithrombin III/thrombin reaction.
abstract: Significant differences between saturation kinetic properties of heparin-stimulated reactions between thrombin and antithrombin III from human and bovine species were observed. In both systems, the apparent Km for antithrombin III was higher than the KD for antithrombin III-heparin interaction, monitored by intrinsic protein fluorescence change. The Km for thrombin and kcat were much higher for proteins of the human species than the bovine species. The apparent Km for one human protein was dependent on the concentration of the other human protein, indicating interaction of the binding events. The reaction product formed from the bovine proteins was a potent inhibitor of the reaction but the product from the human proteins was a poor inhibitor. The major differences between the two species appeared to be related to interaction of thrombin or thrombin derivatives with heparin or heparin-antithrombin III complexes.
mesh_terms: D000818:Animals; D000990:Antithrombin III / Q000378:metabolism*; D001665:Binding Sites / Q000187:drug effects; D002417:Cattle; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D013045:Species Specificity; D013917:Thrombin / Q000378:metabolism*; D014107:Tosyllysine Chloromethyl Ketone / Q000494:pharmacology
chemical_list: D014107:Tosyllysine Chloromethyl Ketone; D000990:Antithrombin III; D006493:Heparin; D013917:Thrombin