A convenient access to αVβ3/αVβ5 integrin ligand conjugates: regioselective solid-phase functionalisation of an RGD based peptide

The cyclopeptide (-RGDfK-) is a potent and selective αVβ3/αVβ5 integrin ligand. A methodology for the conjugation of cyclo(-RGDfK-) through the regioselective derivatisation of lysine side chains, either in solution or directly on the solid support, is described. This provides a rapid and flexible chemical entry to conjugated integrin ligands bearing reporter groups for biological investigations or reactive chemical functions for the preparation of new vector systems.