Alternations in quantities and activities of erythrocyte cytosolic carbonic anhydrase isoenzymes in glucose-6-phosphate dehydrogenase-deficient individuals

Background: This study was designed to evaluate the quantitative and activity alterations of cytosolic carbonic anhydrase (CA) isoenzymes in the erythrocytes of glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals. Methods: Western Blot and CA esterase activity analysis were employed to measure cytosolic erythrocyte CA isoenzymes. Results: The total CA activities were analyzed from erythrocytes of 30 healthy and 30 G6PD-deficient individuals. The mean values with standard error (SE) were 22.9 ± 1.69 U/gHb and 27.2 ± 2.1 U/gHb (P < 0.01), respectively. The ratio of CAI/CAII of G6PD-deficient individuals (1.28 ± 0.06) was significantly lower than that of the normal subjects (3.79 ± 0.18) (P < 0.001). Furthermore, the concentration of CAIII in G6PD-deficient individuals was significantly lower than that of the normal subjects (P < 0.001) and there were significant correlations between the concentration of CAI, CAII, CAIII, and ratio of CAI/CAII, and the activity concentration of G6PD. Conclusions: Different carbonic anhydrase isoenzymes may serve different roles in the G6PD-deficient erythrocyte. CAI could be used as an indicator for hemolytic anemia. CAII is able to compensate for the functions of CAI and increased expression of CAII will promote oxidative damage. CAIII can provide the G6PD-deficient persons with some extent of protection against oxidative damage.