Raman and IR spectroscopy of manganese superoxide dismutase, a pathology biomarker

The vibrational spectrum, Raman and infrared, of manganese superoxide dismutase (MnSOD), is presented.Both Raman and Fourier-Transform (FT) IR spectra of the lyophilised powder of MnSOD strongly suggest that its secondary structure composition is dominated by α-helix and β-sheet which is in good agreement with the crystallographic data. In order to obtain more results on the protein vibrational characterisation and to highlight the suitable experimental conditions a multiwavelength Raman detection was performed at 532, 632.8, 638, 660 and 785 nm. Moreover, we studied the protein behaviour during the lyophilisation process in the presence of the phosphate buffer. Our results show significant differences in the protein conformation and stability during freeze drying of the buffered protein solution compared to the aqueous solution.