Rimmerman, Dolev; Leshchev, Denis; Hsu, Darren; Hong, Jiyun; Abraham, Baxter; Henning, Robert; Kosheleva, Irina; Chen, Lin
Many biomaterials can adapt to changes in local biological environment (such as pH, temperature or ionic composition) in order to regulate function or deliver a payload. Such adaptation to environmental perturbation is typically a hierarchical process that begins with a response on a local structural level and then propagates to supramolecular and macromolecular scales. Understanding fast structural dynamics that occur upon the perturbation is important for rational design of functional biomaterials. However, few nanosecond time-resolved methods can probe both intra- and inter-molecular scales simultaneously with a high structural resolution. Here we utilize time-resolved x-ray scattering to probe nanosecond to microsecond structural dynamics of polypeptides undergoing protonation via a pH jump initiated by photoexcitation of a photoacid. Our results provide insight into the protonation-induced hierarchical changes in packing of peptide chains, formation of helical structure and associated collapse of the peptide chain.