Photocontrol of cell adhesion processes: model studies with cyclic azobenzene-RGD peptides

A photoresponsive integrin ligand was synthesized by backbone-cyclization of a heptapeptide containing the integrin binding motif Arg-Gly-Asp (RGD) with 4-(aminomethyl)phenylazobenzoic acid (AMPB). Surface plasmon enhanced fluorescence spectroscopy showed that binding of the azobenzene peptide to alpha(v)beta(3) integrin depends on the photoisomeric state of the peptide chromophore. The higher affinity of the trans isomer could be rationalized by comparing the NMR conformations of the cis and trans isomers with the recently solved X-ray structure of a cyclic RGD-pentapeptide bound to integrin.