title: Discovery of subnanomolar arginine-glycine-aspartate-based alphaVbeta3/alphaVbeta5 integrin binders embedding 4-aminoproline residues.
abstract: The embodiment of 4-aminoproline residues (Amp) into the arginine-glycine-aspartate (RGD) sequence led to the discovery of a novel class of high-affinity alpha Vbeta 3/alpha Vbeta 5 integrin binders [IC 50 h (alpha Vbeta 3) 0.03-5.12 nM; IC 50 h (alpha Vbeta 5) 0.88-154 nM]. A total of eight cyclopeptides of type cyclo-[-Arg-Gly-Asp-Amp-], 5- 12, were assembled by a standard solid-phase peptide synthesis protocol that involved the C2-carboxyl and C4-amino functionalities of the proline scaffolds, leaving the N (alpha)-nuclear site untouched. Functionalization of this vacant proline site with either alkyl or acyl substituents proved feasible, with significant benefit to the integrin binding capabilities of the ligands. Notably, six out of eight cyclopeptide inhibitors, 5- 7 and 9- 11, showed moderate yet significant selectivity toward the alpha Vbeta 3 receptor. The three-dimensional structure in water was determined by NMR techniques and molecular dynamics calculations. Docking studies to the X-ray crystal structure of the extracellular segment of integrin alpha Vbeta 3 complexed with reference compound 1 were also performed on selected analogues to highlight the structural features required for potent ligand binding affinity.
authors.affiliation: Dipartimento Farmaceutica, Università di Parma, Viale G.P. Usberti 27A, Parma, Italy. franca.zanardi@unipr.it
authors.forename: Franca
authors.initials: F
authors.lastname: Zanardi
authors.forename: Paola
authors.initials: P
authors.lastname: Burreddu
authors.forename: Gloria
authors.initials: G
authors.lastname: Rassu
authors.forename: Luciana
authors.initials: L
authors.lastname: Auzzas
authors.forename: Lucia
authors.initials: L
authors.lastname: Battistini
authors.forename: Claudio
authors.initials: C
authors.lastname: Curti
authors.forename: Andrea
authors.initials: A
authors.lastname: Sartori
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Nicastro
authors.forename: Gloria
authors.initials: G
authors.lastname: Menchi
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Cini
authors.forename: Anna
authors.initials: A
authors.lastname: Bottoncetti
authors.forename: Anna
authors.initials: A
authors.lastname: Bottonocetti
authors.forename: Silvia
authors.initials: S
authors.lastname: Raspanti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Casiraghi
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000737:chemistry / Q000187:drug effects*; D016023:Integrins / Q000737:chemistry / Q000187:drug effects*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D015394:Molecular Structure; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry*; D019030:Receptors, Vitronectin / Q000737:chemistry / Q000187:drug effects*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
chemical_list: D039302:Integrin alphaVbeta3; D016023:Integrins; D009842:Oligopeptides; D019030:Receptors, Vitronectin; C064660:integrin alphaVbeta5; C047981:arginyl-glycyl-aspartic acid; D011392:Proline