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Measurement of kinetics of sickle hemoglobin polymerization using absorbance: implications for therapy
Dissertation   Open access

Measurement of kinetics of sickle hemoglobin polymerization using absorbance: implications for therapy

Eli Hunter Worth
Doctor of Philosophy (Ph.D.), Drexel University
Feb 2023
DOI:
https://doi.org/10.17918/00001461
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Abstract

Sickle cell anemia--Treatment Sickle hemoglobin (HbS)
Therapeutic solutions to hinder the effects of sickle hemoglobin (HbS) polymerization are highly sought after. Measuring the kinetics of polymerization of HbS using laser photolysis on carbon monoxide-saturated samples with a multiple beam stochastic method has allowed us to gain valuable insight into the inhibitive ability of different avenues that may be used to alleviate the effects of sickle cell disease. In place of using scattering from laser light to probe the extent of polymerization, we use excess absorbance which occurs due to the diffusion of additional monomers into photolyzed regions undergoing polymerization. Two possible inhibitors to polymerization were researched using this method, the first being HbS-Chiapas which contains an additional mutation to the hemoglobin molecule, substituting the [alpha]114 proline for an arginine along with the [beta]6 mutation inherent to ordinary HbS. Results from HbS/S-Chiapas mixtures indicate an inhibitive effect on par with that of fetal hemoglobin (HbF). The other inhibitor was Voxelotor (GBT440), a drug intended to impede polymerization by maintaining the liganded R-state confirmation over a wider range of bound ligands than ordinary HbS. We tested whether voxelotor provided any inhibitive effects to polymerization in the unliganded state, finding that the binding of the drug afforded no additional hindrance to polymerization.

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