title: Crotavirin, a potent platelet aggregation inhibitor purified from the venom of the snake Crotalus viridis.
abstract: A potent platelet aggregation inhibitor in the venom of Crotalus viridis snake was purified to homogeneity by gel filtration chromatography and reverse phase high-performance liquid chromatography. This purified principle, named crotavirin, is a single-chain polypeptide with a mol. wt of 9200 as estimated by SDS-polyacrylamide gel electrophoresis. It inhibited the aggregation of human washed platelets induced by collagen, thrombin and thomboxane analogue (U46619) with a similar IC50 (approximately 1.0 micrograms/ml, 0.11 microM). The binding of fluorescein isothiocyanate-conjugated crotavirin to platelets was abolished in the presence of divalent cation chelator, EDTA, indicating that divalent cation is essential for crotavirin's binding. A monoclonal antibody, 7E3, raised against platelet glycoprotein IIb-IIIa complex blocked the binding of fluorescein isothiocyanate-conjugated crotavirin to platelets, whereas the other monoclonal antibody against glycoprotein IIb-IIIa, 10E5, had no inhibitory effect. In addition, crotavirin inhibited in a concentration-dependent manner the binding of fluorescein isothiocyanate-conjugated rhodostomin, a member of the disintegrin family, to platelets. Its binding to platelets was blocked by disintegrins, e.g. trigramin and rhodostomin. It is concluded that crotavirin is a potent platelet aggregation inhibitor, which acts specifically on an epitope of glycoprotein IIb-IIIa, leading to the blockade of fibrinogen binding to glycoprotein IIb-IIIa and eventually the blockade of platelet aggregation.
authors.affiliation: Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: C Z
authors.initials: CZ
authors.lastname: Liu
authors.forename: H C
authors.initials: HC
authors.lastname: Peng
authors.forename: T F
authors.initials: TF
authors.lastname: Huang
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002413:Cations, Divalent / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D017839:Crotalus; D004492:Edetic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D006801:Humans; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D002413:Cations, Divalent; D002614:Chelating Agents; D003435:Crotalid Venoms; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C098620:crotavirin; C072026:rhodostomin; D004492:Edetic Acid; D016650:Fluorescein-5-isothiocyanate