title: Hypersulfated low molecular weight heparin with reduced affinity for antithrombin acts as an anticoagulant by inhibiting intrinsic tenase and prothrombinase.
abstract: In buffer systems, heparin and low molecular weight heparin (LMWH) directly inhibit the intrinsic factor X-activating complex (intrinsic tenase) but have no effect on the prothrombin-activating complex (prothrombinase). Although chemical modification of LMWH, to lower its affinity for antithrombin (LA-LMWH) has no effect on its ability to inhibit intrinsic tenase, N-desulfation of LMWH reduces its activity 12-fold. To further explore the role of sulfation, hypersulfated LA-LMWH was synthesized (sLA-LMWH). sLA-LMWH is not only a 32-fold more potent inhibitor of intrinsic tenase than LA-LMWH; it also acquires prothrombinase inhibitory activity. A direct correlation between the extent of sulfation of LA-LMWH and its inhibitory activity against intrinsic tenase and prothrombinase is observed. In plasma-based assays of tenase and prothrombinase, sLA-LMWH produces similar prolongation of clotting times in plasma depleted of antithrombin and/or heparin cofactor II as it does in control plasma. In contrast, heparin has no effect in antithrombin-depleted plasma. When the effect of sLA-LMWH on various components of tenase and prothrombinase was examined, its inhibitory activity was found to be cofactor-dependent (factors Va and VIIIa) and phospholipid-independent. These studies reveal that sLA-LMWH acts as a potent antithrombin-independent inhibitor of coagulation by attenuating intrinsic tenase and prothrombinase.
authors.affiliation: Hamilton Civic Hospitals Research Centre and Department of Medicine, McMaster University, Hamilton, Ontario L8V 1C3, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Anderson
authors.forename: J C
authors.initials: JC
authors.lastname: Fredenburgh
authors.forename: A R
authors.initials: AR
authors.lastname: Stafford
authors.forename: Y S
authors.initials: YS
authors.lastname: Guo
authors.forename: J
authors.initials: J
authors.lastname: Hirsh
authors.forename: V
authors.initials: V
authors.lastname: Ghazarossian
authors.forename: J I
authors.initials: JI
authors.lastname: Weitz
mesh_terms: D000925:Anticoagulants / Q000493:pharmacokinetics*; D000991:Antithrombins / Q000378:metabolism*; D001665:Binding Sites; D001777:Blood Coagulation / Q000187:drug effects; D002021:Buffers; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D015853:Cysteine Proteinase Inhibitors; D004305:Dose-Response Relationship, Drug; D015951:Factor Xa / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism; D006493:Heparin / Q000737:chemistry* / Q000378:metabolism* / Q000493:pharmacokinetics; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D009363:Neoplasm Proteins; D010314:Partial Thromboplastin Time; D010504:Periodic Acid / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding; D013455:Sulfur / Q000378:metabolism*; D013925:Thromboplastin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013997:Time Factors
chemical_list: D000925:Anticoagulants; D000991:Antithrombins; D002021:Buffers; D015853:Cysteine Proteinase Inhibitors; D006025:Glycosaminoglycans; D009363:Neoplasm Proteins; D010743:Phospholipids; D010504:Periodic Acid; D013455:Sulfur; D006493:Heparin; D013925:Thromboplastin; C009288:metaperiodate; D015951:Factor Xa; D003546:Cysteine Endopeptidases; C030910:cancer procoagulant