Photochemical techniques for studying the flexibility of polypeptides

Knowledge of peptide dynamics and flexibility is of importance for understanding and predicting the folding mechanisms of proteins and their functions. The present work gives an overview and applies a fluorescence-based technique to investigate the dynamics and flexibility of peptides with different lengths and varying sequences. This new technique takes full advantage of fluorescence for detection as compared to the previously employed transient absorption. The length dependence of end-to-end collision rates suggests that the behavior of peptides is far from that of an ideal chain, and the strong sequence dependence of peptide flexibility allows one to extract a flexibility scale for amino acids in peptides. The rigidifying character of a polyproline backbone, the effect of charges on the end-to-end collision frequency and the flexibility of β-peptides in comparison to their α homologues are also studied.