ИСТИНА

Vibrational spectroscopy is widely employed in the study of protein structure. Spectral intervals that can be used to characterize structure of a protein molecule and its function-related conformational changes have been selected based on the analysis of the Raman and FTIR spectra. Conventional analysis of the protein structure based on the Raman and FTIR data employs the results of measurements in the fingerprint range. However, the results of theoretical study and computer simulations of protein macromolecules show the presence of low-frequency vibrational modes that correspond to conformation-sensitive intramolecular motions of relatively large parts of a molecule. The characteristic frequencies of such modes belong to the THz frequency range. Significant recent progress in the THz spectroscopy has stimulated interest in the application of spectroscopic methods in the low-frequency spectral range aimed at characterization of protein structure. We employ low-frequency Raman and FTIR spectroscopy in the study of several proteins with different secondary structures. The analysis of spectral data makes it possible to reveal several conformation-sensitive bands in the low frequency spectra of proteins. Variations in relative intensities and shifts of the bands are analyzed versus the known contents of the main secondary-structure elements (alpha helix, beta sheet, and random coil). Correlations of spectral changes in the low-frequency and fingerprint spectral ranges are studied. Keywords: Low-frequency Raman spectroscopy, FTIR spectroscopy, secondary structure, conformation-sensitive bands