Potential of Raman spectroscopic techniques to study proteins

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 258; p. 119712
• Main Authors: Kuhar, Nikki, Sil, Sanchita, Umapathy, Siva
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 05.09.2021
• Subjects: Amide bonds; Bovine serum albumin; Deconvolution; Lysozyme; Protein-misfolding; Proteins; Raman optical activity; Raman spectroscopic techniques; Raman spectroscopy; Proteins; Bovine serum albumin; Deconvolution; Protein-misfolding; Amide bonds; Raman optical activity; Raman spectroscopy; Raman spectroscopic techniques; Lysozyme
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2021.119712

[Display omitted] •Misfolded proteins are implicated in various diseases.•Raman spectra contain plenty of information about the secondary and tertiary structure of proteins.•Proteins having different structures can be distinguished using specific Raman signatures without labeling.•Specific Raman signatures are obtained with the change in micro-environment around protein side chains.•Raman spectrum of complex bio-systems like bacteria etc contains specific signatures for proteins.•Surface-Enhanced Raman Spectroscopy, Tip-Enhanced Raman spectroscopy can probe single molecules of proteins.•Raman Optical Activity can differentiate between hydrated and unhydrated α-helices and β-sheets. Proteins are large, complex molecules responsible for various biological processes. However, protein misfolding may lead to various life-threatening diseases. Therefore, it is vital to understand the shape and structure of proteins. Despite numerous techniques, a mechanistic understanding of the protein folding process is still unclear. Therefore, new techniques are continually being explored. In the present article, we have discussed the importance of Raman spectroscopy, Raman Optical Activity (ROA) and various other advancements in Raman spectroscopy to understand protein structure and conformational changes based on the review of our earlier work and recent literature. A Raman spectrum of a protein provides unique signatures for various secondary structures like helices, beta-sheets, turns, random structures, etc., and various amino acid residues such as tyrosine, tryptophan, and phenylalanine. We have shown how Raman spectra can differentiate between bovine serum albumin (BSA) and lysozyme protein based on their difference in sequence and structure (primary, secondary and tertiary). Although it is challenging to elucidate the structure of a protein using a Raman spectrum alone, Raman spectra can be used to differentiate small changes in conformations of proteins such as BSA during melting. Various new advancements in technique and data analyses in Raman spectroscopic studies of proteins have been discussed. The last part of the review focuses on the importance of the ROA spectrum to understand additional features about proteins. The ROA spectrum is rich in information about the protein backbone due to its rigidity compared to its side chains. Furthermore, the ROA spectra of lysozyme and BSA have been presented to show how ROA provides extra information about the solvent properties of proteins.