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Water, Ions, and Hemoglobin: Effects on Allostery and Polymerization
Maria A Rotter1, Jie Jiang1, Stephanie M Ferrone1
1Department of Physics , Drexel University , Philadelphia , Pennsylvania 19104 , United States.
The Journal of Physical Chemistry. B
|September 18, 2018
Summary
Solvent interactions affect hemoglobin function. Studies show crowding alters oxygen binding via ion linkage, and phosphate concentration influences sickle hemoglobin polymerization through a double nucleation mechanism.
Area of Science:
- Biochemistry
- Molecular Biology
- Physical Chemistry
Background:
- Proteins in aqueous solutions are sensitive to solvent effects.
- Hemoglobin's function can be modulated by external factors.
- Understanding these interactions is crucial for protein behavior.
Purpose of the Study:
- To investigate solvent perturbations on hemoglobin function.
- To elucidate the mechanism of altered oxygen binding in hemoglobin.
- To quantitatively analyze sickle hemoglobin polymerization in phosphate buffers.
Main Methods:
- Experimental studies on hemoglobin-solvent interactions.
- Analysis of oxygen binding with crowding agents and osmoticants.
- Quantitative analysis of sickle hemoglobin polymerization using a double nucleation model.
Main Results:
- Hemoglobin oxygen binding is altered by crowding species through linked ion binding (Cl-, CO2), not buried surface.
- Sickle hemoglobin polymerization increases with phosphate concentration.
- Solubility changes explain increased monomer addition and nucleation rates in sickle hemoglobin.
Conclusions:
- Solvent effects, particularly ion linkage, play a key role in hemoglobin allosteric energetics.
- The double nucleation mechanism accurately describes sickle hemoglobin polymerization.
- Incorporating interstitial water into nucleation models is a novel approach for sickle hemoglobin analysis.
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