Definition: An anticoagulant principle that is a component of various tissues (especially liver and lung) and mast cells in humans and several mammalian species; its principal and active constituent is a glycosaminoglycan composed of d-glucuronic acid and d-glucosamine, both sulfated, in 1,4-a linkage, of molecular weight between 6,000 and 20,000. In conjunction with a serum protein cofactor (the so-called heparin cofactor), heparin acts as an antithrombin and an antiprothrombin. Synthetic preparations are commonly used in therapeutic anticoagulation. It also enhances activity of “clearing factors” (lipoprotein lipases).
Synonym(s): heparinic acid
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