Distortion of β-globin chain of hemoglobin alters the pathway of erythrocytic glucose metabolism through band 3 protein.

OBJECTIVE

Band 3 is a transmembrane protein of erythrocytes and its cytosolic part regulates glucose metabolism to proceed along the pentose phosphate pathway (PPP) or glycolytic pathway by binding with the central cavity of the β chain of deoxygenated hemoglobin and with some glycolytic enzymes competitively. In β thalassemia major and hemoglobin (Hb)Eβ thalassemia, β chain is either absent or distorted and glucose metabolism may be disturbed. We estimated adenosine triphosphate (ATP), glucose 6-phosphate dehydrogenase (G6PD) and aldolase activity in oxygenated and deoxygenated state of erythrocytes of β major, HbEβ thalassemia and normal controls to understand the hypothesis that major glucose metabolism within the erythrocytes of these diseases may proceed through the PPP.

METHODS

Fifty of each group of patients and 52 normal controls were included. Patients' blood was collected 1 month prior to blood transfusion. G6PD and aldolase were estimated using a commercial kit. ATP was measured by spectrophotometric method.

RESULTS

Significantly low levels of erythrocytic ATP and higher levels of G6PD were found in two groups of patients. Aldolase level in deoxygenated hemolysate was significantly higher than oxygenated hemolysate in normal controls but no significant change was noticed in both types of thalassemic patients.

CONCLUSIONS

In β thalassemia major and HbEβ thalassemia due to distortion of β chain, binding of deoxygenated hemoglobin with band 3 is inhibited and thus traffic control of glycolytic pathway is disturbed and shifted towards PPP.