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Polyphasic linkage between protein solubility and ligand binding in the hemoglobin-polyethylene glycol system
The Journal of Biological Chemistry
|October 10, 1980
Summary
Polyethylene glycol (PEG) induces hemoglobin precipitation, altering oxygen affinity. This shift is linked to oxygen saturation and hemoglobin
Area of Science:
- Biochemistry
- Molecular Biology
- Hematology
Background:
- Hemoglobin's oxygen binding is crucial for oxygen transport.
- Hemoglobin S causes sickle cell disease due to altered properties.
- Polyethylene glycol (PEG) is used to precipitate proteins.
Purpose of the Study:
- To investigate the effect of polyethylene glycol (PEG) on hemoglobin solubility and oxygen affinity.
- To explore the thermodynamic linkage between hemoglobin solubility and oxygen binding.
- To compare PEG-induced precipitation with natural gelation of hemoglobin S.
Main Methods:
- Precipitation of dilute hemoglobin A, S, and horse hemoglobin using polyethylene glycol (PEG).
- Measurement of oxygen affinity in two-phase systems formed by PEG and hemoglobin.
- Electron microscopy to analyze the structure of precipitated deoxyhemoglobin S.
Main Results:
- Polyethylene glycol (PEG) induced precipitation of hemoglobins without affecting soluble oxygen affinity.
- Precipitation levels correlated with oxygen saturation, indicating linked solubility and affinity.
- Deoxyhemoglobin A and S showed decreased oxygen affinity upon precipitation, while horse hemoglobin showed increased affinity.
- Electron microscopy revealed identical structures for PEG-induced and naturally gelled deoxyhemoglobin S.
Conclusions:
- Hemoglobin solubility and oxygen affinity are thermodynamically linked processes.
- PEG provides a model system to study these linked phenomena, independent of specific solid-phase structures.
- The findings offer insights into hemoglobin behavior and potential therapeutic strategies.