Application of FTIR and Raman Spectroscopy to Study the Structure of Serum Albumin in Solutions and Films

Various vibrational spectroscopy methods have great potential for use in disease diagnostics. The development and standardization of such techniques is an urgent biomedical task. This work is devoted to comparing the capabilities of ATR FTIR spectroscopy and Raman scattering for studying the structure of proteins in solutions and films of various compositions. In this work, the parameters of the secondary structure of bovine serum albumin (BSA) are determined in water and 0.15M NaCl solutions as well as in films made by the drying of these solutions. It is shown that α-helix quantity in BSA increases, and the amount of β-sheets is reduced after the dehydration. Analysis of Raman peaks from aromatic amino acids indicated a lowering of their degree of hydration in NaCl-containing film in comparison with film, prepared from water solution. This allows us to conclude that the protein structure is closer to the native globule in the presence of NaCl. Despite the fact that the BSA structure can be considered native in all the conditions studied, we should note that different water and salt contents in the sample affect the spectral properties and conformational state of the protein.