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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
Disulfide bond influence on protein structural dynamics probed with 2D-IR vibrational echo spectroscopy
Haruto Ishikawa1, Seongheun Kim, Kyungwon Kwak
1Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.
Summary
Intramolecular disulfide bonds regulate protein dynamics. Disrupting the disulfide bond in neuroglobin (Ngb) accelerates fast protein fluctuations, revealing its role in inhibiting protein dynamics.
Area of Science:
- Protein dynamics
- Biophysics
- Structural biology
Background:
- Intramolecular disulfide bonds influence protein stability and activity by covalently linking protein components.
- Fast (subpicosecond to ~100 ps) protein equilibrium structural fluctuations remain experimentally uncharacterized regarding disulfide bond influence.
- Neuroglobin (Ngb) is a vertebrate brain protein with a globin fold, reversibly binding oxygen, and possessing an intramolecular disulfide bond absent in myoglobin (Mb).
Purpose of the Study:
- To experimentally investigate the constraints imposed by an intramolecular disulfide bond on the fast structural fluctuations of neuroglobin (Ngb).
- To characterize the effects of disulfide bonds on protein equilibrium structural dynamics using ultrafast spectroscopy.
Main Methods:
- Ultrafast 2D-IR vibrational echo spectroscopy was employed to examine structural fluctuations in Ngb.
- The study observed CO spectral diffusion in Ngb-CO with and without the disulfide bond to probe protein dynamics.
- Comparison of linear FTIR spectra and 2D-IR measurements were used to assess the impact of the disulfide bond.
Main Results:
- Despite similar linear FTIR spectra, 2D-IR measurements revealed accelerated equilibrium sampling of protein configurations upon disulfide bond disruption.
- The intramolecular disulfide bond in Ngb was shown to inhibit fast protein dynamics.
- Eliminating the disulfide bond did not induce significant conformational changes in Ngb's structure.
Conclusions:
- The intramolecular disulfide bond in Ngb acts as an inhibitor of fast protein dynamics.
- Fast protein dynamics are sensitive to the presence of intramolecular disulfide bonds, even without major conformational changes.
- Ultrafast 2D-IR spectroscopy is a powerful tool for characterizing the role of disulfide bonds in protein dynamics.
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