Study of the secondary structure of proteins in aqueous solutions by attenuated total reflection Fourier transform infrared spectrometry

✍ Scribed by Jean-Marc Millot; Nadia Allam; Michel Manfait

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 782 KB
• Volume: 295
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(94)80228-9

✦ Synopsis

An approach to the determination of secondary structure content in proteins in aqueous solutions based on attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectrometry is proposed. ATR-FT-IR spectra of eleven proteins with known crystal structures were recorded. An algorithm for careful subtraction of the solvent background was developed and the reproducibility of the spectra was established for a wide range of protein concentrations in aqueous solutions. Two techniques were compared for the determination of secondary structure content [classical least-squares analysis (CLS) and partial least-squares analysis (PLS)] and optimum conditions for their utilization were suggested. The best correlation between the ATR-FT-IR approach and X-ray diffraction data was obtained with the PLS analysis and the distinction of four types of secondary structures (ordered and disordered a-helix, B-sheet and undefined conformation). The averages of the differences in the percentage content between X-ray and IR secondary structures predicted in the ATR mode are 7.1% and 2.8% for the ordered and disordered cr-helix, respectively, 6.5% for the B-sheet and 4.7% for the undefined structure.