In contrast, the promotion of antithrombin-mediated inactivation of thrombin appears to occur solely by the ability of large heparin molecules to physically bind both heparin and thrombin, bringing them into close proximity to one another. In the case of Factor X, binding of heparins to Antithrombin III appears to directly activate antithrombin's enzymatic activity against Factor X. The mechanisms by which heparins promote antithrombin-mediated inactivation of Factor X and Thrombin are distinct.This level of knowledge is sufficient for most medical students however, for the sake of interest we delve slightly deeper below. As mentioned, heparins potently enhance the enzymatic activity of Antithrombin III which serves to inhibit activated Thrombin and Factor X (See: Coagulation for a review of the actions of antithrombins).UFH and LMWH display slightly distinct pharmacological properties that yield different pharmacokinetics and anticoagulation profiles. Newer classes, known as Low Molecular Weight Heparin (LMWH), are derived by purification of the smaller molecules within UFH. The original class, Unfractionated Heparin (UFH), is a crude mixture of variable length polysaccharides derived from porcine intestinal mucosa.
Two basic classes of heparins have been generated.
As a consequence, heparins serve as powerful anticoagulants.
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