Synthesis and Structure−Activity Relationships of Linear and Conformationally Constrained Peptide Analogues of CIYKYY as Src Tyrosine Kinase Inhibitors
A series of peptideanalogues of Ac-CIYKYY (1) were synthesized by functional group modifications in peptide side chains or by introducing conformational constraints, to improve the inhibitory potency against active Src kinase. Ac-CIYKF(4-NO2)Y (2, IC50 = 0.53 microM) and conformationallyconstrainedpeptide 31 (IC50 = 0.28 microM) exhibited 750- and 1400-fold higher inhibitory activities, respectively