Terahertz Protein Vibrations: The Usefulness of Coarse-Grained Numerical Models

Understanding the way in which proteins vibrate in their folded state is pivotal for a broad comprehension of their biological activity. In particular, vibrations in the terahertz range are indicated in the current literature as being involved in protein conformational changes. Nowadays, frequencies around or below 1 THz can be detected for example by Raman spectroscopy using proper ultra-low frequency filters. In previous studies, some of the authors performed modal analysis of all-atom lattice models to investigate the expansion-contraction mode shapes associated to low-frequency Raman peaks detected experimentally on lysozyme and Na+/K+-ATPase powder samples. In this contribution, all-atom calculations are compared to new ones derived from a simplified coarse-grained mechanical model; the latter was built-up considering only Cα atoms, i.e., the protein backbone. The efficacy of the coarse-grained model in describing delocalized and global expansion-contraction protein vibrations as well as its limitations are discussed.