title: Effect of low molecular weight heparin preparations on the inhibition of thrombin by heparin cofactor II.
abstract: 1. Heparin molecules approximately 24 to 30 residues in length are required to catalyze the thrombin-HC II reaction. The requirement for heparin molecules of this length is consistent with a model for catalysis in which heparin binds HC II and thrombin simultaneously to form a ternary complex in a manner similar to that proposed for the thrombin-AT III reaction. Smaller molecules (18 or more monosaccharide units in length) are required to catalyze the thrombin-AT III reaction. 2. The specific AT III-binding pentasaccharide containing 3-O-sulfated glucosamine is not required for activity with HC II. 3. Some low molecular weight heparin preparations have significant activity with HC II (approximately 10 to 20% that of standard heparin). This is probably related to the presence of species with molecular weights greater than 6000 to 7500 (24 to 30 monosaccharide units) in these preparations.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.
authors.forename: D M
authors.initials: DM
authors.lastname: Tollefsen
authors.forename: T
authors.initials: T
authors.lastname: Sugimori
authors.forename: M M
authors.initials: MM
authors.lastname: Maimone
mesh_terms: D000990:Antithrombin III / Q000502:physiology; D015844:Heparin Cofactor II / Q000502:physiology*; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology*; D006801:Humans; D009844:Oligosaccharides / Q000494:pharmacology; D013917:Thrombin / Q000037:antagonists & inhibitors*
chemical_list: D006495:Heparin, Low-Molecular-Weight; D009844:Oligosaccharides; D015844:Heparin Cofactor II; D000990:Antithrombin III; D013917:Thrombin