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Aggregation of normal and sickle hemoglobin in high concentration phosphate buffer
Kejing Chen1, Samir K Ballas, Roy R Hantgan
1Department of Physics, Wake Forest University, Winston-Salem, North Carolina, USA.
Biophysical Journal
|October 7, 2004
Summary
Sickle cell disease involves hemoglobin S polymerization. High phosphate buffer models show hemoglobin aggregation below solubility, unlike physiological conditions, impacting study interpretations.
Area of Science:
- Biochemistry
- Hematology
- Biophysics
Background:
- Sickle cell disease (SCD) arises from abnormal hemoglobin S polymerization under low oxygen.
- Understanding SCD pathophysiology and treatment requires accurate modeling of hemoglobin S polymerization.
- High concentration phosphate buffer models are used to study SCD, necessitating validation against physiological conditions.
Purpose of the Study:
- To investigate hemoglobin S and hemoglobin A aggregation in high concentration phosphate buffer.
- To compare polymerization characteristics in the high phosphate model versus physiological conditions.
- To assess the applicability of the high phosphate model for SCD research.
Main Methods:
- Static light scattering (SLS)
- Dynamic light scattering (DLS)
- Differential interference contrast microscopy (DICM)
- Turbidity measurements
Main Results:
- Hemoglobin S and A aggregate in high phosphate buffer below defined solubility limits.
- Aggregation increases with temperature (15-37°C) and phosphate concentration.
- Aggregation was not observed in 0.05 M phosphate buffer or a dextran-based model.
- Aggregation is detectable by SLS, DLS, and DICM, but not by turbidity.
Conclusions:
- High phosphate buffer models exhibit hemoglobin aggregation phenomena not seen in vivo.
- Turbidity measurements may underestimate polymerization in the high phosphate model.
- Careful interpretation is needed when applying high phosphate model findings to SCD pathophysiology.