INHIBITION OF ANTI-THROMBIN ACTIVITY OF ALPHA-2-MACROGLOBULIN

  • 1 January 1979
    • journal article
    • research article
    • Vol. 288  (10) , 887-889
Abstract
The interaction between thrombin and .alpha.-2-macroglobulin was studied on human purified materials, in the presence or absence of heparin, by kinetic analysis of thrombin inhibition and polyacrylamide gel electrophoresis. In the absence of heparin, binding of thrombin to .alpha.-2-macroglobulin, shown by electrophoresis, leads to the loss of the coagulant property of the enzyme. In the presence of heparin the rate of inhibition of thrombin clotting activity by .alpha.-2-macroglobulin is decreased. Heparin binds to thrombin, impairing the formation of thrombin-.alpha.-2-macroglobulin complex. Heparin paradoxically protects thrombin from inhibition by .alpha.-2-macroglobulin but it increases the enzyme inhibition by antithrombin III. Such a phenomenon could be of practical interest for treatment of thrombosis in patients with high plasma level of .alpha.-2-macroglobulin and low level of antithrombin III, such as occurs in the nephrotic syndrome.

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