INTERACTION OF HEPARIN WITH PLASMA-PROTEINS - DEMONSTRATION OF DIFFERENT BINDING-SITES FOR ANTITHROMBIN-III COMPLEXES AND ANTITHROMBIN-III

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 95  (1) , 69-80
Abstract
Affinity chromatography of [human] plasma and serum with the use of heparin conjugated Sepharose confirmed the existence of 2 types of protein binding sites. A minor heparin fraction bound free AT III [antithrombin III] selectively and firmly but not its protease complexes. The complexes bound less firmly to another, much larger heparin fraction, together with a select group of the plasma proteins at physiological pH and ionic strength. These included complement [c] proteins (C1q), C2, factor B, properdin and .beta.1H [.beta.-globulin regulating alternate pathway of C]), protease inhibitors (inter-.alpha.-trypsin inhibitor and C3b [C3, fragment b] inactivator) and cell surface proteins (protein HC [human complex-forming glycoprotein, heterogeneous in charge] and fibronectin) as well as .beta.-lipoproteins. Affinity chromatography with heparin-Sepharose was extremely useful as an early preparative step in the isolation of these minor plasma components. The said proteins apparently could be linked to cell surfaces carrying heparinoids in the intercellular space.