FTIR Characterization of REV Proteins and Lipids

Fourier-transform infrared spectroscopy (FTIR) was used to characterize the protein and lipid content of REVs based on the specific vibrations of these molecules^{24 (link),31 (link)}. FTIR measurements were carried out using a Varian 2000 spectrometer (Scimitar Series, USA), fitted with a diamond attenuated total reflection cell (‘Golden Gate’ single reflection ATR unit, Specac, United Kingdom). Approximately 5 μl of the sample was pipetted onto the diamond ATR surface and a thin dry film was obtained by slowly evaporating the solvent under ambient conditions (approx. 10 min). Typically, 64 scans were collected at a nominal resolution of 2 cm⁻¹. ATR correction, buffer background spectral subtraction and other spectral evaluations were performed with the Grams/32 software package (Galactic Inc., USA).