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Allosteric changes in protein structure computed by a simple mechanical model: hemoglobin T<-->R2 transition.
Chunyan Xu1, Dror Tobi, I Bahar
1Center for Computational Biology and Bioinformatics, and Department of Molecular Genetics and Biochemistry, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Journal of Molecular Biology
|October 1, 2003
Summary
A simple mechanical model reveals hemoglobin
Area of Science:
- Biophysics
- Structural Biology
- Protein Dynamics
Background:
- Protein dynamics are typically studied indirectly via spectroscopy or simulations.
- Molecular simulations often face challenges with sampling and computational cost for large proteins.
Purpose of the Study:
- To investigate the dynamics of hemoglobin (Hb) using a novel mechanical model.
- To predict the transition between the tense (unliganded) and relaxed (ligand-bound) forms of Hb.
Main Methods:
- Utilized a mechanical model based on Gaussian fluctuations of protein residues.
- Analyzed the collective dynamics and conformational transitions of hemoglobin.
Main Results:
- The model efficiently predicts the tense-to-relaxed transition in Hb.
- Global motion, driven by entropy, favors the T to R2 transition.
- Loss of hinge-bending at specific interfacial residues in the R2 form correlates with decreased cooperativity.
Conclusions:
- Hemoglobin has an intrinsic tendency to transition from the T to R2 state.
- Allosteric signal propagation involves hinge regions and proximal histidine residues.
- Elastic forces of entropic origin drive the T to R2 transition in Hb.