β-turn formation by a six-residue linear peptide in solution

A model peptide AAGDYY-NH2 (beta1), which is found to adopt a beta-turn conformation in the TEM-1 beta-lactamase inhibitor protein (BLIP) in the TEM-1/BLIP co-crystal, was synthesized to elucidate the mechanism of its beta-turn formation and stability. Its structural preferences in solution were comprehensively characterized using CD, FT-IR and H-1 NMR spectroscopy, respectively. The set of observed diagnostic NOEs, the restrained molecular dynamics simulation, CD and FT-IR spectroscopy confirmed the formation of a beta-turn in solution by the model peptide. The dihedral angles [(phi(3), phi(3)) (phi(4), phi(4))] of [(-52degrees, -32degrees) (-38degrees, -44degrees)] of Gly-Asp fragment in the model peptide are consistent with those of a type III beta-turn. in a conclusion, the conformational preference of the linear hexapeptide beta1 in solution was determined, and it would provide a simple template to study the mechanism of beta-turn formation and stability.