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The binding of CO2 to human hemoglobin
The Journal of Biological Chemistry
|July 25, 1975
Summary
Human hemoglobin binds carbon dioxide differently depending on whether it is oxygenated or deoxygenated. Deoxyhemoglobin exhibits two distinct binding sites for carbon dioxide, unlike carbonmonoxyhemoglobin.
Area of Science:
- Biochemistry
- Physiology
- Molecular Biology
Background:
- Hemoglobin plays a crucial role in oxygen and carbon dioxide transport in the blood.
- Understanding hemoglobin's interaction with carbon dioxide is vital for respiratory physiology.
Purpose of the Study:
- To investigate the carbon dioxide-dissociation curves of human deoxyhemoglobin and carbonmonoxyhemoglobin.
- To determine the binding characteristics of carbon dioxide to different hemoglobin states.
Main Methods:
- Utilized a rapid mixing technique combined with ion exchange chromatography.
- Measured CO2-dissociation curves under varying pH and PCO2 conditions at 37°C.
Main Results:
- Deoxyhemoglobin's CO2-dissociation curves required a model with two classes of binding sites.
- A significant difference in carbon dioxide affinity (factor of 3) was observed between these sites on deoxyhemoglobin's alpha and beta chains.
- Carbonmonoxyhemoglobin showed no differential reactivity among its four terminal alpha-amino groups for CO2.
Conclusions:
- Human deoxyhemoglobin possesses distinct binding affinities for carbon dioxide on its alpha and beta chains.
- The terminal alpha-amino groups of carbonmonoxyhemoglobin exhibit uniform reactivity towards carbon dioxide.