Thalassemia-like abnormalities of the red cell membrane in hemoglobin E trait and disease.
In recent studies, we observed a decrease of KMapp, an abnormally biphasic kinetics of the red cell membrane neutral phosphatase and an increased binding of hemoglobin to the membrane in various forms of beta-thalassemia. Since the gene encoding the beta chain (beta E chain) of hemoglobin E (HbE) is endowed with some thalassemic characteristics, we studied the erythrocyte membrane in 25 individuals with Hb E trait or disease. The apparent Michaelis-Menten constant for p-nitrophenylphosphate (the artificial substrate used) was significantly decreased, as in beta-thalassemia. However, the kinetics was monophasic in all the heterozygotes and in four of the homozygotes. It was biphasic only in the three other homozygotes. Vmax was also significantly reduced, a fact that is masked, when not reversed in beta-thalassemia, owing to the rejuvenation of the red cell population. In 5 mM phosphate buffer (pH 8.00), the binding of Hb E to the erythrocyte ghosts was increased in the homozygotes. In the heterozygotes, Hb A binding was also increased, as is the case in beta-thalassemia. This latter fact suggests that the membrane binding site(s) of hemoglobin is (are) altered. We found a highly significant increase of Hb F in EE subjects. The present study extends to the red cell membrane the beta-thalassemic phenotype associated with the beta E gene.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004905:Erythrocyte Aging; D004909:Erythrocyte Indices; D004910:Erythrocyte Membrane / Q000201:enzymology*; D005260:Female; D006446:Hemoglobin E / Q000235:genetics*; D006455:Hemoglobins, Abnormal / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010744:Phosphoric Monoester Hydrolases / Q000097:blood; D013789:Thalassemia / Q000097:blood
D006455:Hemoglobins, Abnormal; D006446:Hemoglobin E; D010744:Phosphoric Monoester Hydrolases