Syntheses and activities of backbone-side chain cyclic octapeptide ligands with <i>N</i>
-functionalized phosphotyrosine for the <i>N</i>
-terminal SH2-domain of the protein tyrosine phosphatase SHP-1
hydrophobicity of formed lactam bridges on stimulatory activity. All tested linear and cyclic octapeptides stimulate the phosphataseactivity of SHP‐1. Stimulatory activities of cyclic ligands increase with the chain length of the lactam bridges resulting in increased flexibility and better entropic preformation of the binding conformation. The strong activity of some cyclic octapeptides supports the modelled