@article{3062276, title = "Structure-activity relationships of αIIb 313-320 derived peptide inhibitors of human platelet aggregation", author = "Stanica, R.M. and Benaki, D. and Rodis, F.I. and Mikros, E. and Tsoukatos, D. and Tselepis, A. and Tsikaris, V.", journal = "Journal of Peptide Science", year = "2008", volume = "14", number = "11", pages = "1195-1202", issn = "1075-2617, 1099-1387", doi = "10.1002/psc.1060", keywords = "alanine; alanylmethionylglutamylserylarginylalanylaspartylarginine; fibrinogen; fibrinogen receptor; fibrinogen receptor antagonist; glutamic acid; methionine; octapeptide; peptide derivative; serine; synthetic peptide; tyrosine; tyrosylalanylglutamylserylarginylalanylaspartylarginine; tyrosylmethionylalanylserylarginylalanylaspartylarginine; tyrosylmethionylglutamylalanylarginylalanylaspartylarginine; tyrosylmethionylglutamylserylalanylalanylaspartylarginine; tyrosylmethionylglutamylserylarginylalanylalanylarginine; tyrosylmethionylglutamylserylarginylalanylaspartylalanine; tyrosylmethionylglutamylserylarginylalanylaspartylarginine; tyrosylmethionylglutamylserylarginylalanylaspartylarginyllysylleucylalanylglutamylvalylglycylarginylvalyltyrosylleucylphenylalanylleucine; unclassified drug, amino acid sequence; amino acid substitution; article; biological activity; controlled study; drug protein binding; human; nuclear magnetic resonance spectroscopy; peptide synthesis; priority journal; protein conformation; protein function; protein structure; sequence analysis; signal transduction; structure activity relation; thrombocyte aggregation inhibition, Arginine; Aspartic Acid; Humans; Integrin beta3; Magnetic Resonance Spectroscopy; Molecular Conformation; Oligopeptides; Peptides; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Membrane Glycoprotein IIb; Protein Conformation; Spectrometry, Mass, Electrospray Ionization; Structure-Activity Relationship; von Willebrand Factor", abstract = "The αIIbβ3 receptor, which is the most abundant receptor on the surface of platelets, can interact with a variety of adhesive proteins including fibrinogen, fibronectin and the von Willebrand factor. Fibrinogen binding on α IIbβ3 is an event essential for platelet aggregation and thrombus formation. Mapping of the fibrinogen-binding domains on αIIb subunit suggested the sequence 313-332 as a possible binding site. This region was restricted to sequence αIIb 313-320 (Y313MESRADR320) using synthetic octapeptides overlapping by six residues. The YMESRADR octapeptide inhibits ADP-stimulated human platelets aggregation and binds to immobilized fibrinogen. In this study, we used the Ala scanning methodology within the sequence 313-320 aiming to evaluate the contribution of each amino acid in inhibiting platelet aggregation. It was found that the substitution of Y313, M314, E315 or S316 by A does not affect the activity of the parent octapeptide. The-RADR-motif seems to be the most essential for the biological activity of the αIIb 313-320 site. The conformational analysis of the YAESRADR, YMESAADR and YMESRAAR analogs by using NMR spectroscopy and distance geometry calculations revealed significant differences in their conformational states in DMSO-d6. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd." }