A comparative evaluation of the activities of thiol group and hydroxyl group in low-frequency vibrations using terahertz spectroscopy and DFT calculations.

Low-frequency vibrations of biomolecules govern many biological processes like allostery of proteins, binding interaction and solvation. Revealing how involved are different groups of molecules in low-frequency vibrations is of significance to understand the behaviors of biomolecules. To compare the activities of hydroxyl group and thiol group in low-frequency vibrations, we conducted THz measurements and DFT calculations of l‑serine and l‑cysteine. We performed quantitative analyses on their low-frequency vibrations to study their difference. Statistical analyses on the vibrational modes in our studied range suggest the thiol group shows a higher level of activity in low-frequency vibrations than hydroxyl group.