Discovery of subnanomolar arginine-glycine-aspartate-based alphaVbeta3/alphaVbeta5 integrin binders embedding 4-aminoproline residues.
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.
Zanardi
Franca
F
Dipartimento Farmaceutica, Università di Parma, Viale G.P. Usberti 27A, Parma, Italy. franca.zanardi@unipr.it
Burreddu
Paola
P
Rassu
Gloria
G
Auzzas
Luciana
L
Battistini
Lucia
L
Curti
Claudio
C
Sartori
Andrea
A
Nicastro
Giuseppe
G
Menchi
Gloria
G
Cini
Nicoletta
N
Bottoncetti
Anna
A
Bottonocetti
Anna
A
Raspanti
Silvia
S
Casiraghi
Giovanni
G
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
D039302:Integrin alphaVbeta3; D016023:Integrins; D009842:Oligopeptides; D019030:Receptors, Vitronectin; C064660:integrin alphaVbeta5; C047981:arginyl-glycyl-aspartic acid; D011392:Proline