A new short chain RGD-containing disintegrin, accutin, inhibits the common pathway of human platelet aggregation.
A new short-chain disintegrin, accutin, was purified from the Formosan Agkistrodon acutus venom by using of gel filtration, ion exchanger and reverse phase HPLC. The homogeneous protein is a 47-residue polypeptide with a molecular mass of 5241 Da containing an Arg-Gly-Asp sequence and seven cysteinyl residues at positions highly homologous to other disintegrins. Accutin dose-dependently inhibited human platelet aggregation stimulated by ADP, collagen, thrombin or the thromboxane analogue U46619 in platelet suspension with IC50 values of 66-267 nM. It was also active in inhibiting platelet aggregation of platelet-rich plasma. However, accutin apparently did not affect the shape change caused by these agonists. Accutin also inhibited fibrinogen-induced aggregation of human elastase-treated platelets in a dose-dependent manner. Furthermore, accutin dose-dependently inhibited the binding reaction of fluorescein isothiocyanate (FITC)-conjugated arietin, a member of the disintegrin family, to human platelets. In addition, the binding of FITC-conjugated accutin to platelets was almost completely blocked by a monoclonal antibody, 7E3, raised against the platelet glycoprotein IIb/IIIa complex. On the other hand, accutin as well as other disintegrins, rhodostomin and arietin, exhibited an inhibitory effect on 7E3 binding toward platelets and endothelial cells in a dose-dependent manner. It is concluded that accutin, a new platelet aggregation inhibitor belonging to the short-chain disintegrin family, acts specifically on a binding epitope of GPIIb/IIIa overlapping with that of 7E3, leading to the blockade of fibrinogen binding to its receptor.
Yeh
C H
CH
Pharmacological Institute, College of Medicine, National Taiwan University, No. 1, Sec. 1, Jen-Ai Rd, Taipei, Taiwan.
Peng
H C
HC
Yih
J B
JB
Huang
T F
TF
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism; D002850:Chromatography, Gel; D003435:Crotalid Venoms / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D019483:Disintegrins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000032:analysis; D010455:Peptides / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors / Q000302:isolation & purification*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors; D019030:Receptors, Vitronectin / Q000037:antagonists & inhibitors
D000596:Amino Acids; D003435:Crotalid Venoms; D019483:Disintegrins; D036341:Intercellular Signaling Peptides and Proteins; D009842:Oligopeptides; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019030:Receptors, Vitronectin; C115498:accutin; C069270:arietin; C047981:arginyl-glycyl-aspartic acid; D016650:Fluorescein-5-isothiocyanate