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Characterization of Sickling During Controlled Automated Deoxygenation with Oxygen Gradient Ektacytometry
Published on: November 5, 2019
Universal metastability of sickle hemoglobin polymerization.
Weijun Weng1, Alexey Aprelev, Robin W Briehl
1Department of Physics, Drexel University, Philadelphia, PA 19104, USA.
Journal of Molecular Biology
|March 1, 2008
Summary
Sickle hemoglobin polymerization stops before reaching equilibrium solubility. This study reveals that both uniform solutions and droplets show higher final monomer concentrations than expected, impacting polymer fraction analysis.
Area of Science:
- Biophysics
- Hematology
- Polymer Science
Background:
- Sickle hemoglobin (HbS) polymerization is central to sickle cell disease pathophysiology.
- Polymerization is understood to occur when deoxyHbS concentration exceeds equilibrium solubility.
Purpose of the Study:
- To investigate the final monomer concentration of sickle hemoglobin during polymerization in uniform bulk solutions.
- To compare these findings with previous experiments using sickle hemoglobin droplets.
- To understand the factors influencing the termination of HbS polymerization.
Main Methods:
- Utilized modulated excitation of trace amounts of carbon monoxide (CO) in sickle hemoglobin (HbS) gels.
- Measured the recombination rate of photolyzed CO to determine deoxyHbS concentration in the solution phase.
- Compared measurements from uniform bulk solutions with sickle cell hemoglobin droplets suspended in oil.
Main Results:
- Final monomer concentration in uniform solutions and droplets consistently exceeds equilibrium solubility.
- The degree to which solubility is exceeded depends on initial HbS concentration and gel formation conditions.
- Observed that approximately 67% of the expected polymer mass forms, suggesting polymerization termination is not solely solubility-driven.
Conclusions:
- Sickle hemoglobin polymerization termination occurs at concentrations above thermodynamic solubility.
- Polymer growth obstruction, influenced by factors like external forces, affects final monomer concentration.
- These findings necessitate a re-evaluation of analyses predicting polymer fraction in sickle cell disease research.
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