Sickle hemoglobin is more fusogenic than normal hemoglobin at physiological pH and ionic strength conditions

Abstract

We used electron microscopy, quasi-elastic light scattering and static light scattering to show that human hemoglobin (Hb) interacts with bovine brain phosphatidylserine lipid vesicles and promotes vesicle fusion in an isotonic buffer at pH 7.4. The fusogenic properties of Hb were observed in both small unilamellar vesicles (SUVs) and large unilamellar vesicles (LUVs). A simple turbidity measurement method was used to follow increases in vesicle size (scattering diameter) as a function of time. For the first 3 h, upon incubation with oxygenated Hb, the scattering diameters of vesicles increased at a rate of 7.8 nm/h for LUVs. Continuous incubation with Hb led to complicated vesicle fusion, probably due to the oxidation products of Hb and lipid molecules. In the absence of both Hb and lipid oxidation, using Hb liganded with carbon monoxide, we obtained, for the entire 20 h incubation period, a fusion rate of 2.9 nm/h for LUVs. We also studied interactions between sickle Hb and vesicles under the same conditions and found that the vesicle fusion rates for sickle Hb were about 2 times faster than those for normal Hb. These results showed that sickle Hb exhibited more extensive interactions with lipid bilayer than normal Hb at physiological pH and ionic strength conditions, and provide insights toward understanding the molecular mechanisms in sickle cell abnormalities.

Circulating cell membrane microparticles transfer heme to endothelial cells and trigger vasoocclusions in sickle cell disease

“…46 Our data show that met-Hb is associated with both plasma MPs and purified erythrocyte MPs, suggesting that cell-free Hb in plasma is oxidized to met-Hb. Met-Hb releases heme readily from its prosthetic pocket and this is enhanced by repeated cycles of deoxygenation and polymerization.…”

Cation Modulation of Hemoglobin Interaction with Sodium n-Dodecyl Sulfate (SDS). I: Calcium Modulation at pH 7.20

“…Each dialysis set up had a total volume of 2 l. Sickle and normal red cells were processed in tandem to ensure identical buffer conditions. Since the molecular properties of HbA and HbS are to be compared, parallel processing of HbA and HbS was critical so as to eliminate a number of confounding variables introduced when samples had different histories [32]. The Hb samples were then concentrated using micro filters prior to use.…”

Comparison between two different hemichromes of hemoglobins (HbA and HbS) induced by n-dodecyl trimethylammonium bromide: Chemometric study

“…1). Since the molecular properties of HbA and HbS are to be compared, parallel processing of both HbS was critical so as to eliminate a number of confounding variables introduced when samples had different histories [63].…”