Examination of the effect of some vitamins on glucose-6-phosphate dehydrogenase enzyme purified from sheep liver

The enzyme glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) is the first and rate-limiting enzyme of the pentose phosphate pathway, which is essential for the integrity and function of red blood cells. In this study, G6PD was purified 6308-fold in a single step by affinity chromatography from sheep liver. The molecular weight of the G6PD enzyme was found to be 93 kDa with SDS-PAGE. Vmax and KM values were calculated as 0.58 (μmol/min).mL-1 and 1.44 mM, respectively. The effect of biotin (vitamin B7) and folic acid (vitamin B9) vitamins on G6PD activity was examined. Biotin and folic acid had a significantly inhibitory effect on G6PD activity. The IC50 values of biotin and folic acid vitamins were calculated as 61.64 μM and 17.21 μM, respectively. Ki values and inhibitory types of these vitamins were found by Lineweaver-Burk graphs. The inhibitory type of these vitamins was determined as non-competitive inhibitory. Ki values for biotin and folic acid were calculated as 121.13 μM and 22.73 μM, respectively. The increase in the activity of the G6PD enzyme in various cancer diseases causes the rapid development of cancer cells. Therefore, G6PD inhibitors can be a very important treatment method in cancer treatment. In this study, it was concluded that biotin and folic acid vitamins may be effective in cancer treatment with their inhibitory effect on G6PD.