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Relationship between protein/solvent proton exchange and progressive conformation and fluctuation changes in
1Laboratoire de Biologie Physico-Chimique, Université Paris VII, France.
European Journal of Biochemistry
|July 20, 1990
Summary
Changes in hemoglobin structure and dynamics are linked to pH variations and ligand binding. Increased affinity correlates with reduced protein fluctuations and altered subunit interactions.
Area of Science:
- Biochemistry
- Structural Biology
- Physical Chemistry
Background:
- Oxyhemoglobin exhibits pH-dependent structural changes at the tertiary and quaternary levels.
- Previous research in our lab observed these structural reorganizations at the alpha beta interface.
Purpose of the Study:
- To determine if pH-induced structural changes in hemoglobin result from proton exchange with the solvent.
- To investigate the impact of external proton concentration on hemoglobin's structural and dynamic properties.
Main Methods:
- Infrared spectroscopy
- Acid/base titration
- Proton-deuterium (1H/2H) exchange
- Study performed on carbonmonoxy hemoglobin for higher ligand affinity.
Main Results:
- Affinity changes in hemoglobin are closely related to protein fluctuations and structural modifications.
- Increased affinity (via ligand replacement or pH change) is associated with constrained protein chains and reduced fluctuations.
- A looser alpha beta interface association is observed with increased affinity.
Conclusions:
- pH influences hemoglobin structure and dynamics through proton exchange.
- Protein fluctuations and quaternary structure rearrangements are key to hemoglobin's functional modulation by pH and ligands.