Cooperative metal-coordination and ion pairing in tripeptide recognition

The recognition of tripeptides by a metal-centered receptor consisting of a rigid backbone region and variable tripeptide arms is described. The studies showed that the receptor was selective for L-Xxx-L-Lys-L-Lys, with Xxx = His, Cys, and Met, giving association constants near 1.0 x 10(5) M-1. Binding enhancement through cooperative interactions of the peptidic arms is demonstrated.