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Proton Transfer and Protein Conformation Dynamics in Photosensitive Proteins by Time-resolved Step-scan Fourier-transform Infrared Spectroscopy
Published on: June 27, 2014
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FTIR spectroscopy of flavin-binding photoreceptors
Daichi Yamada1, Hideki Kandori
1Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya, 466-8555, Japan.
Methods in Molecular Biology (Clifton, N.J.)
|April 26, 2014
Summary
Light-induced difference Fourier transform infrared (FTIR) spectroscopy reveals protein structure-function relationships. Controlling water content allows detailed analysis of protein-bound water and hydrogen bonds in photoreceptive proteins.
Area of Science:
- Biophysics
- Spectroscopy
- Structural Biology
Background:
- Photoreceptive proteins are crucial for biological light sensing.
- Fourier transform infrared (FTIR) spectroscopy is a powerful tool for studying protein dynamics.
- Water absorption in the infrared spectrum presents challenges for FTIR analysis of biological samples.
Purpose of the Study:
- To detail the methodology of light-induced difference FTIR spectroscopy for studying photoreceptive proteins.
- To demonstrate how controlled water content enhances FTIR analysis of protein structure-function.
- To investigate hydrogen bonding and protein-bound water in various photoreceptive systems.
Main Methods:
- Established three sample preparation methods: hydrated film, redissolved sample, and concentrated solution.
- Utilized light-induced difference FTIR spectroscopy across the mid-IR region (4,000–800 cm⁻¹).
- Analyzed vibrations of S-H, O-H (water), and O-H (tyrosine) stretches to probe hydrogen bonds.
Main Results:
- Accurate difference FTIR spectra were obtained for LOV and BLUF domains using hydrated films.
- Enzymatic turnover of (6-4) photolyase was studied, isolating enzyme-substrate binding signals.
- Concentrated solutions were suitable for drying-sensitive proteins like DASH-type cryptochromes.
Conclusions:
- Light-induced difference FTIR spectroscopy, with controlled hydration, is effective for studying protein structure-function.
- The method provides insights into protein-bound water and hydrogen bond dynamics.
- This technique is adaptable to various photoreceptive proteins, including those sensitive to drying.
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