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Specific interactions of the allosteric effector 2,3-bisphosphoglycerate with human hemoglobin--a difference FTIR
Biological Chemistry Hoppe-Seyler
|June 1, 1993
Summary
2,3-bisphosphoglycerate (BPG) binding to human deoxy-hemoglobin (deoxy-HbA) alters oxygen affinity. BPG binding stabilizes the T-structure, decreasing oxygen binding by forming hydrogen and electrostatic bonds.
Area of Science:
- Biochemistry
- Molecular Biology
- Spectroscopy
Background:
- Hemoglobin's oxygen affinity is regulated by allosteric effectors.
- 2,3-bisphosphoglycerate (BPG) is a key allosteric regulator of hemoglobin function.
Purpose of the Study:
- To investigate the specific interactions between 2,3-bisphosphoglycerate (BPG) and human deoxy-hemoglobin (deoxy-HbA).
- To elucidate how these interactions modulate hemoglobin's oxygen affinity.
Main Methods:
- Difference Fourier Transform Infrared (FTIR) spectroscopy was employed to study BPG-deoxy-HbA interactions.
- Analysis focused on hydrogen bonding and electrostatic interactions at the molecular level.
Main Results:
- A hydrogen bond forms between beta 82 Lysine (Lys) and BPG's carboxylate group in deoxy-HbA.
- BPG's phosphate groups are fully deprotonated, inducing electrostatic stress and forming hydrogen bonds with histidines (beta 2, beta 143).
- Interactions favor the deoxy-HbA T-structure, reducing oxygen affinity.
Conclusions:
- BPG binding to deoxy-HbA involves a combination of hydrogen bonds and electrostatic interactions.
- These interactions stabilize the low-affinity T-state of hemoglobin, thereby decreasing oxygen affinity.