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Relationship between protein structural fluctuations and rebinding dynamics in ferric haem nitrosyls
Neil T Hunt1, Gregory M Greetham, Michael Towrie
1Department of Physics, University of Strathclyde, Glasgow, Scotland, UK.
The Biochemical Journal
|November 12, 2010
Summary
Ultrafast 2D-IR spectroscopy reveals how protein pocket flexibility in haem proteins like myoglobin and cytochrome c affects nitric oxide (NO) rebinding. More flexible pockets correlate with slower NO release, impacting biological function.
Area of Science:
- Biophysics
- Spectroscopy
- Protein Dynamics
Background:
- Nitric oxide (NO) interactions with haem proteins are crucial in biological systems.
- Understanding the relationship between protein dynamics and ligand binding is essential for elucidating biological function.
Purpose of the Study:
- To investigate haem nitrosylation using ultrafast 2D-IR spectroscopy.
- To correlate haem environment vibrational dynamics with NO ligand rebinding kinetics after photolysis.
- To compare these dynamics in myoglobin (Mb) and cytochrome c (Cc).
Main Methods:
- Ultrafast 2D-IR spectroscopy.
- Time-resolved IR pump-probe studies.
- Analysis of haem nitrosylation in Mb and Cc.
Main Results:
- Myoglobin pockets exhibit greater flexibility than cytochrome c pockets.
- Increased pocket flexibility in Mb correlates with slower NO rebinding kinetics compared to Cc.
- Cytochrome c shows two distinct structural sub-sites at room temperature.
Conclusions:
- Protein pocket flexibility directly influences NO ligand rebinding and biological functionality.
- Findings support the validity of linear response theories in protein-ligand interactions.
- 2D-IR spectroscopy provides insights into protein structural dynamics and sub-site populations.
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