Biomolecule large-amplitude motion and solvation dynamics: Modelling and probes from THz to X-rays

Biomolecules are innately flexible, and undergo large-amplitude motions that affect the surrounding solvation shell. Dynamical X-ray scattering provides direct insight into global shape changes that the biomolecule undergoes during folding (1 nm and up length scale). THz spectroscopy directly probes solvation and collective motions on a somewhat smaller length scale (0.3-1 nm). Infrared spectroscopy looks at the influence of such motions on localized vibrational modes (up to 0.5 nm length scale). Molecular dynamics simulations and models of vibrational energy flow within biomolecules complement such experimental studies by providing a molecular-level explanation for the experimental observations. In this review, we consider the interplay between simulation and experiment across length scales for biomolecules such as carbohydrates and globular proteins.