Effect of MDA level on G6PD activity and membrane proteins changes in anemic cases

Introduction: Glucose 6-phosphate dehydrogenase (G6PD) is the first and rate restricting enzyme in the hexose monophosphate shunt. Malondialdehyde (MDA) generated through decomposition of peroxided lipids influences the intrinsic mechanical properties of the red blood cell (RBC) membrane, which leads to reduced deformability. In this study we investigated effect of MDA on G6PD activity and membrane protein abnormalities in vitro. Materials and methods: The hematological findings were obtained by a blood cell counter and high-pressure liquid chromatography (HPLC) for 47 cases. G6PD enzyme activity was measured with Beutler's et al. method and MDA levels in plasma were measured by thiobarbituric acid (TBA) assay. Erythrocyte ghosts were prepared according to Dodge et al. method and membrane proteins were separated using on 8.3 % SDS-PAGE. DNA samples were isolated from white blood cells as described by Poncz et al. method to perform amplification refractory mutation system (ARMS) and restriction fragment length polymorphism (RFLP) assays. Results: Total 47 cases were examined as a G6PD deficient, anemic and normal group in this study and found no correlation between parameters statistically. In addition, we found no differences between groups about G6PD, MDA and some RBCs membrane proteins data. Moreover, we found differences between groups to G6PD deficient and anemic or normal samples for spectrin membrane protein data and between normal and G6PD deficient or anemic groups for band 4.1 data. Conclusion: Although in a previous in vivo study indicated that MDA inactivated the enzyme, and the amount of inactivation increased with MDA concentration, we found statistically no correlation between MDA and any other parameters. This may be due to the prior removal of oxidatively injured cells from the circulation. Since cross-linking of membrane components may stiffen the RBC membrane, injured MDA-rich cells may be removed by splenic entrapment