The Constrained Amino Acid β‐Acc Confers Potency and Selectivity to Integrin Ligands

Complete opposites: The incorporation of the rigid building block (+)-β-Acc (Acc=aminocyclopropane carboxylic acid) into cyclic RGD peptides results in a high affinity towards the integrin αvβ3. The peptides 1 and 2 are composed of the enantiomeric building blocks (+)- (blue) and (−)-β-Acc (red). The active peptide 1 inhibits integrin αvβ3 mediated cell adhesion to vitronectin with an IC50 value of 20 nM.