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A comparative study of red blood cell membranes from normal subjects and beta-thalassemia and sickle cell anemia patients was performed by spin labeling at the lipidic and protein phase. The results show that the quantity of bound spin label is the same for sickle, thalassemic, and normal membranes. The data from 5-doxyl stearic acid suggest an increase in fluidity for the thalassemic membrane.

The interaction of bis-(N-maleimidomethyl) ether with oxyhemoglobin results in covalent linkages of both maleimide groups, converting them to succinyl derivatives of beta93 Cys and beta97 His at their sulfhydryl and imidazolyl side chains, respectively. The resultant hemoglobin is stable, and reveals a left-shifted oxyhemoglobin equilibrium curve in which cooperativity is abolished. This reagent readily traverses the red cell membrane and prevents the sickling reaction upon deoxygenation. It appears to affect none of the activities of the red cell enzymes adversely, nor does it appear to affect the red cell membrane. Since there are several defined effects on the stereochemical status of the molecule conferred by interaction with bis-(N-maleimidomethyl) ether, the precise mechanism of the anitsickling effect remains to be elucidated. A more subtle perturberant will be required to specify a precise antisickling effect. By use of bis-(N-maleimidomethyl) ether a precise locus on the beta chain of human hemoglobin S can be perturbed to produce the desired effect.