Raman Microspectroscopy of Hair: Low-Frequency Markers of Protein Secondary Structure

Low-frequency intervals that can be used to study the secondary structure of proteins are determined. Compared are Raman spectra of keratins from unpigmented human hair, measured in two experimental configurations: with excitation radiation coaxial with the hair and perpendicular to it. Based on the polarization sensitivity, the bands peaked at 150 and 221 cm-1 are assigned to vibrations of α-helical structures. The comparison of Raman spectra of hair fragments with different contents of secondary structure elements shows that the vibrations of β-structure are manifested in a spectral interval of 270-340 cm-1. The results obtained for a particular object (hair keratin) can be used in the study of the secondary structure of proteins.