Peptide Models for Studying Autonomous Folding of Subdomain Sections of Protein Molecules

Polypeptide segments are the elementary folding units of globular proteins. Relatively short synthetic polypeptide segments are essential models for the investigation of the mechanism of folding of globular proteins. The search for intermediate, partially folded states of proteins, or their fragments, is a central issue in the protein folding problem. In order to be able to characterize partially folded states, it is essential to be able to characterize the conformation of polypeptide segments in the presumably unfolded (statistical coil) and fully folded states. To this end, a series of model polypeptide segments, labeled by pairs of fluorescent probes, were prepared and characterized by means of time resolved dynamic non-radiative fluorescence energy transfer (FRET) measurements.