title: Fibrin(ogen) peptide B beta 15-42 inhibits platelet aggregation and fibrinogen binding to activated platelets.
abstract: The binding of fibrinogen to activated platelets leads to platelet aggregation. Fibrinogen has multiple binding sites to platelet membrane glycoprotein IIb-IIIa complex. At least two well-defined sequences in fibrinogen, Arg-Gly-Asp sequence of A alpha 95-97 and A alpha 572-574 and gamma 400-411, have been shown to interact with glycoprotein IIb-IIIa. A possible binding site on the amino-terminal end of fibrinogen to platelet glycoprotein IIb-IIIa has also been reported. In this paper the effect of synthetic peptides derived from the amino-terminal end of the B beta chain on platelet aggregation and fibrinogen binding has been examined. B beta 15-42 peptide inhibits platelet aggregation and 125I-fibrinogen binding to activated platelets in a dose-dependent manner. Since B beta 15-42 contains a previously identified fibrinogen binding site, B beta 15-18, exposed by thrombin cleavage of native fibrinogen, we also examined the effect of B beta 15-18, B beta 19-42, and B beta 1-14 (fibrinopeptide B) on platelet aggregation and fibrinogen binding. Synthetic fibrinopeptide B and B beta 15-18 had no effect on platelet aggregation and fibrinogen binding while B beta 19-42 retained the inhibitory effect. When fibrinogen is chromatographed on a column of agarose-bound B beta 15-42, a cation-dependent retention of fibrinogen on the peptide column was observed, and fibrinogen was eluted from the column by B beta 15-42 but not by B beta 1-14. Under the same conditions, platelet glycoprotein IIb-IIIa was not retained in the column. Thus, the observed inhibitory effect is due to its interaction with fibrinogen rather than to platelet glycoprotein IIb-IIIa.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Washington, Seattle 98195.
authors.forename: C S
authors.initials: CS
authors.lastname: Chen
authors.forename: S H
authors.initials: SH
authors.lastname: Chou
authors.forename: P
authors.initials: P
authors.lastname: Thiagarajan
mesh_terms: D001665:Binding Sites; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D005338:Fibrin Fibrinogen Degradation Products; D005340:Fibrinogen / Q000378:metabolism / Q000494:pharmacology*; D005345:Fibrinopeptide B / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; D010446:Peptide Fragments; D010980:Platelet Membrane Glycoproteins; C033786:fibrinogen Bbeta (15-42); D005345:Fibrinopeptide B; D005340:Fibrinogen