Elastin-like proteins (ELPs) are biologically important proteins and models for intrinsically disordered proteins (IDPs) and dynamic structural transitions associated with coacervates and liquid-liquid phase transitions. However, the conformational status below and above coacervation temperature and its role in the phase separation process is still elusive. Employing matrix least-squares global Boltzmann fitting of the circular dichroism spectra of the ELPs (VPGVG)20 , (VPGVG)40 , and (VPGVG)60 , we found that coacervation occurs sharply when a certain number of repeat units has acquired β-turn conformation (in our sequence setting a threshold of approx. 20 repeat units). The character of the differential scattering of the coacervate suspensions indicated that this fraction of β-turn structure is still retained after polypeptide assembly. Such conformational thresholds may also have a role in other protein assembly processes with implications for the design of protein-based smart materials.
Keywords: circular dichroism; elastin-like proteins; intrinsically disordered proteins; matrix least-squares global fitting; protein assembly.
© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.