First-Principles Predictions of Vibrational Raman Optical Activity of Globular Proteins

Computational methods based on the Schrodinger equation have been traditionally confined to rather small molecules. Using an automatic computational methodology, however, we obtained a stunning agreement between experimental and theoretical vibrational spectra of large globular proteins containing thousands of atoms as well. Principle atomic properties are obtained from small molecular fragments and combined with a minimal accuracy loss. This first-principles interpretation of the data reveals a wealth of information, such as nature of localized molecular motions as well as collective vibrational modes describing folding of larger protein parts. A new insight is provided to the origin of the chiroptical effects, and the theory lends the used spectroscopic techniques, unpolarized Raman scattering and vibrational Raman optical activity, immense potential to structural studies of biological systems.