Raman Tensors and their application in structural studies of biological systems

Abstract

The Raman scattering of a molecule is generated by interactions of its electrons with incident light. The electric vector of the Raman scattered light is related to the electric vector of the incident light through a characteristic Raman tensor. A unique Raman tensor exists for each Raman-active molecular vibrational mode. In the case of biologically important macromolecules Raman tensors have been determined for a few hundred vibrational Raman bands. These include proteins and their amino acid constituents, as well as nucleic acids (DNA and RNA) and their nucleotide constituents. In this review Raman tensors for 39 representative vibrational Raman bands of biological molecules are considered. We present details of the Raman tensor determinations and discuss their application in structural studies of filamentous bacteriophages (fd, Pf1, Pf3 and PH75), fowl feather rachis and eyespots of the protists, Chlamydomonas and Euglena.

Polarized raman spectroscopy for determining the orientation of di‐d‐phenylalanine molecules in a nanotube

“…In general, a Raman tensor relates the polarization direction of the exciting light to the polarization direction of the scattered light . A Raman tensor corresponding to a particular vibrational mode can be described in terms of three non‐zero components (principal axes) that can be determined using polarized Raman spectroscopic measurements . The procedure for determining the orientation of chemical groups based on polarized Raman spectroscopy has been previously reported …”

IM30 triggers membrane fusion in cyanobacteria and chloroplasts

“…We determine the orientations of the local-mode ls based on the transition charges in the amide plane 66,67 and the orientations and magnitudes of the as based on previous work of Tsuboi et al 68 The orientation distribution of the ester groups in the MGDG/PG lipid monolayer layer was determined from a published MD trajectory 69 .…”

Structural Organization of Insulin Fibrils Based on Polarized Raman Spectroscopy: Evaluation of Existing Models

“…The largest polarizability oscillation for the amide I vibration of the isolated amide chromophore occurs along the line that is in the plane of the peptide group and at an angle of 34°with respect to the peptide CO bond. 79,84 However, Krim et al has shown that vibrations of adjacent amide chromophores are coupled and delocalized along the polypeptide backbone. 51,85 Furthermore, Asher and co-workers have experimentally demonstrated that the amide I vibrational mode exhibited noticeable interamide coupling in the α-helix conformation.…”

“…89 As mentioned previously, the angle of 34°has been reported between this tensor and the peptide CO bond for the isolated amide chromophore. 79,84 Once the angle between the carbonyl group and the PART is known, the orientation order parameters for the CO bonds, ⟨P 2 ⟩ CO and ⟨P 4 ⟩ CO , can be calculated from the experimentally determined ⟨P 2 ⟩ and ⟨P 4 ⟩ values using the Legendre addition theorem. 90 Figure 6B shows the most probable orientation distribution function of CO groups in the disordered parts of an insulin fibril ( Figure 6B, red curve) calculated based on ⟨P 2 ⟩ CO and ⟨P 4 ⟩ CO .…”