Biomaterial Database

Studies on the mechanism of the rate-enhancing effect of heparin on the thrombin-antithrombin III reaction. 1979

E Holmer, and G Söderström, and L O Andersson

The rate of the reaction between thrombin and antithrombin III is greatly increased in the presence of heparin. Several mechanisms for this effect are possible. To study the problems commercial heparin was fractionated into one fraction of high anticogulant activity and one of low anticoagulant activity by affinity chromatography on matrix-bound antithrombin III. The strength of the binding of the two heparin fractions to antithrombin III and thrombin, respectively, was determined by a crossed immunoelectrophoresis technique. As was to be expected, the high activity fraction was strongly bound to antithrombin III while the low activity fraction was weakly bound. In contrast, thrombin showed equal binding affinity for both heparin fractions. The ability of the two heparin fractions to catalyse the inhibition of thrombin by antithrombin III was determined and was found to be much greater for the high activity heparin fraction. A mechanism for the reaction between thrombin and antithrombin III in the presence of small amounts of heparin is suggested, whereby antithrombin III first binds heparin and this complex then inhibits thrombin by interaction with both the bound heparin and the antithrombin III.

UI	MeSH Term	Description	Entries
D007123	Immunoelectrophoresis, Two-Dimensional	Immunoelectrophoresis in which a second electrophoretic transport is performed on the initially separated antigen fragments into an antibody-containing medium in a direction perpendicular to the first electrophoresis.	Immunoelectrophoresis, Crossed,Immunoelectrophoresis, 2-D,Immunoelectrophoresis, 2D,2-D Immunoelectrophoresis,2D Immunoelectrophoresis,Crossed Immunoelectrophoresis,Immunoelectrophoresis, 2 D,Immunoelectrophoresis, Two Dimensional,Two-Dimensional Immunoelectrophoresis
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D006493	Heparin	A highly acidic mucopolysaccharide formed of equal parts of sulfated D-glucosamine and D-glucuronic acid with sulfaminic bridges. The molecular weight ranges from six to twenty thousand. Heparin occurs in and is obtained from liver, lung, mast cells, etc., of vertebrates. Its function is unknown, but it is used to prevent blood clotting in vivo and vitro, in the form of many different salts.	Heparinic Acid,alpha-Heparin,Heparin Sodium,Liquaemin,Sodium Heparin,Unfractionated Heparin,Heparin, Sodium,Heparin, Unfractionated,alpha Heparin
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000990	Antithrombin III	A plasma alpha 2 glycoprotein that accounts for the major antithrombin activity of normal plasma and also inhibits several other enzymes. It is a member of the serpin superfamily.	Heparin Cofactor I,Antithrombin III-Alpha,Atenativ,Heparin Co-Factor I,Kybernin,Serpin C1,Thrombate III,Antithrombin III Alpha,Antithrombin IIIAlpha,Cofactor I, Heparin,Heparin Co Factor I
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013917	Thrombin	An enzyme formed from PROTHROMBIN that converts FIBRINOGEN to FIBRIN.	Thrombase,Thrombin JMI,Thrombin-JMI,Thrombinar,Thrombostat,alpha-Thrombin,beta,gamma-Thrombin,beta-Thrombin,gamma-Thrombin,JMI, Thrombin