THz spectroscopic fingerprints of the hydration upon globular protein assembly

Lysozyme is a well-known globular protein that can form self-assembled clusters. Here, we report the results of a study on the changes in solvation dynamics upon increasing protein concentration via THz spectroscopy. We find spectral solvation fingerprints in the THz frequency range, which are clearly distinguished from those for liquid–liquid phase separation or liquid–solid phase separation. Furthermore, we carried out supplementary measurements using dynamic light scattering to characterize the size distribution of the protein clusters. This study sheds light on using THz studies of solvation dynamics to characterize and differentiate protein hydration in the case of protein assembly, liquid–liquid phase separation, and liquid–solid phase separation.