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Published on: August 1, 2010
The structural and functional analysis of the hemoglobin D component from chicken
J E Knapp1, M A Oliveira, Q Xie
1Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
The Journal of Biological Chemistry
|February 26, 1999
Summary
Chicken hemoglobin exhibits enhanced oxygen binding cooperativity, suggesting deoxy hemoglobin tetramers self-associate. Structural analysis reveals key differences from human hemoglobin, with a hydrophobic patch potentially regulating oxygen binding.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biophysics
Background:
- Chicken blood exhibits high oxygen saturation cooperativity, indicating self-association of deoxy hemoglobin tetramers.
- Understanding hemoglobin structure-function relationships is crucial for respiratory physiology.
Purpose of the Study:
- To determine the crystal structure of chicken hemoglobin D in its R-state.
- To investigate the structural basis for enhanced cooperativity in chicken hemoglobins.
Main Methods:
- X-ray crystallography to solve the 2.3-A resolution structure of chicken hemoglobin D.
- Molecular replacement using human oxyhemoglobin phases.
- Refinement of the alpha2 beta2 tetramer model.
- Analysis of electrostatic surface potential for deoxy-Hb D models.
Main Results:
- The crystal structure of chicken hemoglobin D (R-state) was determined.
- Significant structural differences were identified in the alpha and beta subunits compared to human oxyhemoglobin.
- A pronounced hydrophobic patch on the calculated deoxy-Hb D tetramer model was observed, potentially mediating tetramer-tetramer interactions.
Conclusions:
- Chicken hemoglobin D's structure provides insights into its functional properties.
- The identified hydrophobic patch is a potential regulatory site for oxygen binding, possibly involving the distal histidine.
- Enhanced cooperativity in chicken hemoglobins may be regulated by tetramer-tetramer interfaces.
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