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Characterization and oxygen binding properties of des-Arg human hemoglobin
P Tosqui1, C R Bonini-Domingos, M F Colombo
1Departamento de Física, Universidade Estadual Paulista, São José do Rio Preto, Brasil. pritosqui@gmail.com
Summary
Chloride binding stabilizes hemoglobin's low oxygen state. Removing Arg141alpha from hemoglobin alters its oxygen affinity, suggesting this residue is key to chloride's effect on oxygenation.
Area of Science:
- Biochemistry
- Structural Biology
- Physiological Chemistry
Background:
- Chloride ions stabilize the deoxy conformation (low oxygen affinity) of hemoglobin (Hb).
- Arginine 141 on the alpha-chain (Arg141α) is a potential binding site for chloride.
- Des-Arg hemoglobin (des-Arg Hb), lacking Arg141α, serves as a model to study these interactions.
Purpose of the Study:
- To biochemically characterize des-Arg Hb.
- To investigate the effects of chloride binding on the oxygen affinity and cooperativity of des-Arg Hb compared to native human hemoglobin (HbA).
Main Methods:
- Biochemical characterization using electrophoresis, high-performance liquid chromatography (HPLC), and mass spectrometry.
- Measurement and comparison of oxygen affinity and cooperativity in des-Arg Hb and HbA with and without chloride binding.
Main Results:
- Des-Arg Hb exhibits high oxygen affinity and low cooperativity when chloride is bound.
- Chloride binding does not alter the functional characteristics of des-Arg Hb, unlike its effect on HbA.
- Arg141α is implicated in the chloride-mediated modulation of Hb oxygenation.
Conclusions:
- The Arg141α residue plays a significant role in the chloride effect on hemoglobin oxygenation.
- These residues are crucial for reducing Hb oxygen affinity to physiologically relevant levels.
- Understanding these interactions provides insights into hemoglobin function and potential therapeutic targets.
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