Raman Optical Activity of Proteins

Abstract

Raman optical activity ( ROA ) spectroscopy measures a small difference of Raman scattering intensities between excitations with right‐ and left‐circularly polarized incident lights, or the difference between the right‐ and left‐circularly polarized Raman scattering intensities using unpolarized excitation. The ROA spectrum reflects the conformations of chiral molecules most sensitively, providing their detailed structural information in solution. The unique capability of ROA spectroscopy has been utilized to study the conformations of various molecules in solution phase. This article features the applications of ROA spectroscopy to the protein structure analyses. The ROA spectra are particularly sensitive to the secondary structures. Staring from the basic theory of ROA, the experimental setup, and the typical spectral properties of proteins, this article describes the recent applications of ROA to a variety of proteins, including intrinsically disordered protein and chromophoric proteins. Besides, the latest analyses of ROA spectra using advanced calculation methods, and the spectral simulation of oligopeptides, proteins, and protein complexes are also presented.

Conformational Analysis of a Retinal Schiff Base Chromophore in Proteorhodopsin by Raman Optical Activity

“…Raman optical activity (ROA) spectroscopy is a chiro-optical technique and a powerful approach for observing molecular conformations. − One form of ROA is defined as the intensity difference of right- and left-circularly components ( I R – I L ) of Raman scattering after unpolarized excitation. Whereas the ROA signals are typically weaker than the parent Raman signals ( I R + I L ) by 3–4 orders of magnitude, the ROA spectra carry the detailed three-dimensional structural information about chiral molecules.…”