FT-IR Study of Histidine Model Compounds: Key Vibrational Bands of Imidazole Group

Kaitlyn Bonola, Couch Brandon, Wouter Hoff, Maci Petrini, John Sand, Aihua Xie

Abstract


L-Histidine is an important amino acid because it is a key part of the active site of many proteins. The aim of the study was to develop a higher understanding of the structure of protein vibrations.. By measuring the absorption spectra of L-Histidine at low pH and high pH, we can identify infrared signals revealing if the histidine is protonated. The spectra of the L-Histidine side chain, ethylimidazole, the polymer of 8 His residues(8-mer), and 15N-His, were measured to identify key infrared signals from the His side chain. A catalog of absorption signals that correspond to a specific protonation site will provide a tool to analyze FTIR spectra of many proteins. A set of vibrational modes were found to be sensitive to protonation and 15N-labeling, providing tools to identify and analyze His side chains in proteins. The identification of these vibrational bands will lead to a better understanding of the structure and function of proteins.

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References


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