Aggregation of hemoglobin S modified by bifunctional imidoesters

Area of Science:

• Biochemistry
• Hematology
• Molecular Biology

Background:

• Sickle hemoglobin (Hb S) polymerization is the primary cause of sickle cell disease.
• Understanding Hb S aggregation kinetics is crucial for developing therapeutic strategies.

Purpose of the Study:

• To investigate the effects of chemical cross-linking on Hb S structure, function, and aggregation.
• To determine how modified Hb S monomers and oligomers influence the aggregation of native Hb S.

Main Methods:

• Cross-linking of Hb S using dimethyladipimidate (DMA) and dimethyl-3,3'-dithiobispropionimidate (DTBP).
• Separation of modified Hb S into monomer, dimer, and polymer fractions via gel filtration.
• Analysis of oxygen equilibrium curves, stability, solubility, and aggregation kinetics.

Main Results:

• Modified Hb S exhibited left-shifted oxygen equilibrium curves and reduced stability and solubility.
• Intracross-linked monomeric Hb S retained aggregation capability with a delay, while oligomeric Hb S aggregated without delay.
• DMA-modified monomeric Hb S accelerated native deoxy-Hb S aggregation, while oligomeric forms did not influence aggregation kinetics.

Conclusions:

• Chemical cross-linking significantly alters Hb S properties, including oxygen affinity and aggregation behavior.
• Monomeric, cross-linked Hb S can influence the aggregation of native Hb S, suggesting a role in disease pathogenesis.
• Oligomeric, cross-linked Hb S does not appear to participate in nucleation or copolymerization with native Hb S.