The combined use of amide I bands in polarized Raman, IR, and vibrational dichroism spectra for the structure analysis of peptide fibrils and disordered peptides and proteins

Abstract

Raman spectroscopy is generally a versatile tool to explore the structure of proteins and peptides in solution. However, in spite of the development of ultraviolet (UV) resonance Raman spectroscopy as a tool that allows for the investigation of samples with lower concentrations, Raman has not played the same role as infrared (IR) spectroscopy with regard to secondary structure analysis. Reported UV Raman studies have recently focused on the ψ-dependence of amide III as a useful tool for the structural analysis even of disordered peptides. Amide I based structural analysis generally uses visible excitation. Rather than describing the traditional secondary structure analysis

Characterization of Secondary Structures of Model Polypeptides in Solutions with Hyper-Raman Spectroscopy

“…Note that the amide I bands are around 1650 cm –1 in our visible Raman spectra of all three conformations (Figure ). It implies that the amide I band mainly due to the CO stretching mode is strongly affected by the non-coincidence effect, which splits a vibrational mode into various frequencies originating from the resonant transfer of vibrational excitation and thus gives the difference in frequencies observed in different vibrational spectroscopies. ,,, IR, Raman, and HR signals are derived from derivatives of the transition dipole moment, polarizability, and hyperpolarizability of a molecule, respectively, giving rise to the variation of the selection rules. Because HR and IR signals arise from odd orders of electric dipole moment, resulting that HR spectra are closer to IR absorption spectra than Raman spectra.…”

μ-FTIR, μ-Raman, and SERS Analysis of Amide I Spectral Region in Oral Biofluid Samples during Orthodontic Treatment

“…The physical interaction with adjunctive effects or the influence of the measurement system induces a broadening of the spectroscopic signal that can be accounted for by a Gaussian shape. This more frequently occurs in FTIR spectra, and then Gaussians are preferred for modeling the vibrational modes in these cases [ 15 , 25 ]. Components, either Lorentzian- and Gaussian-shaped, were considered for determining a good model of the experimental FTIR spectrum.…”

“…As we observed in previous works [ 2 , 3 , 4 , 5 ], particularly relevant GCF changes seem to be related to the modifications of the secondary configurations of hosted proteins resulting from the complex response of the proteins to the stress of the orthodontic process. For this reason, the analysis of the Amide I region in vibrational spectra can be particularly interesting because it plays a pivotal role in the characterization of protein secondary structure ([ 11 , 12 , 13 , 14 , 15 ] and references therein). The spectrum of the Amide I region is related to C=O bond vibrations ( Figure 1 a).…”

Influence of central sidechain on self-assembly of glycine-x-glycine peptides

“…The formation of sheet-like structures predominantly affects the amide I band position in the respective IR spectra due to interstrand vibrational coupling. [50][51][52] The subsequent self-assembly into tapes and fibrils has a more limited influence. 33 In the case of the canonical b-sheet formation, interstrand vibrational interactions disperses amide I intensities over a large spectral region between 1610 and 1690 cm À1 .…”