Publisher Summary The vibrational spectrum of a molecule is determined by its three-dimensional structure and its vibrational force field. An analysis of this (usually infrared (IR) and Raman) spectrum can therefore provide information on the structure and on intramolecular and intermolecular interactions. The more probing the analysis, the more detailed is the information that can be obtained. Detailed analyses of the vibrational spectra of macromolecules, however, have provided a deeper understanding of structure and interactions in these systems. An important advance in this direction for proteins came with the determination of the normal modes of vibration of the peptide group in N-methylacetamide, and the characterization of several specific amide vibrations in polypeptide systems. Extensive use has been made of spectra-structure correlations based on some of these amide modes, including attempts to determine secondary structure composition in proteins. Polypeptide molecules exhibit many more vibrational frequencies than the amide modes. Over the years, some normal-mode calculations have provided greater insight into the spectra of particular molecules. However, these have often been based on approximate structures or have employed limited force fields. These force fields can now serve as a basis for detailed analyses of spectral and structural questions in other polypeptide molecules. The aim of this chapter is to present these recent developments in the vibrational spectroscopy of peptides, polypeptides, and proteins.

Vibrational spectroscopy and conformation of peptides, polypeptides, and proteins.

Amide modes and protein conformation.

In this work, 26 proteins of different structure, function and properties are investigated by Raman spectroscopy with 488, 532 and 1064 nm laser lines. The excitation lines were chosen in NIR and Vis range as the most common and to show the difference due to normal and resonance effect, sometimes accompanied by the fluorescence. The selected proteins were divided, according to the Structural Classification of Proteins, into four classes according to their secondary structure, i.e. α-helical (α), β-sheet (β), mixed structures (α/β, α + β, s) and others. For all compounds, FT-Raman and two Vis spectra are presented along with the detailed band assignment. To the best of our knowledge, this is the first review showing the potential of Raman spectroscopy for the measurement and analysis of such a large collection of individual proteins. This work can serve as a comprehensive vibrational spectra library, based on our and previous Raman measurements. Copyright © 2013 John Wiley & Sons, Ltd.

Raman spectroscopy of proteins: a review

Optical spectroscopy has been extensively studied as a potential in vivo diagnostic tool that can provide information about both the chemical and morphologic structure of tissue in near real time. Most in vivo studies have concentrated on elastic scattering and fluorescence spectroscopies since these signals can be obtained with a good signal-to-noise ratio quickly. However, Raman spectroscopy, an inelastic scattering process, provides a wealth of spectrally narrow features that can be related to the specific molecular structure of the sample. Because of these advantages, Raman spectroscopy has been used to study static and dynamic properties of biologically important molecules in solution, in single living cells, in cell cultures, and more recently, in tissues. This article reviews recent developments in the attempt to develop diagnostic techniques for precancers and cancers, based on Raman spectroscopy. The article surveys important transformations that
occur as tissues progress from normal to precancer and cancerous stages. We briefly review the extensive
literature that summarizes the features and interpretation of Raman spectra of these molecules in solution, and in progressively more complex biological systems. Finally, spectra obtained from intact tissues are comprehensively reviewed and discussed in terms of the molecular and microscopic literature to develop a framework for analyzing Raman signals to yield information about the molecular changes that occur with neoplasia. The article concludes with our perspective on the potential role of Raman spectroscopy in diagnosing precancer and cancerous tissues.

https://www.spiedigitallibrary.org/journals/Journal-of-Biomedical-Optics/volume-1/issue-1/0000/Raman-spectroscopy-for-the-detection-of-cancers-and-precancers/10.1117/12.227815.pdf

P. J. Desmeules

Papers

Determination of the secondary structure of proteins by laser Raman spectroscopy

Determination of the secondary structure of proteins by laser raman spectroscopy