Kinetic properties of glucose-6-phosphate dehydrogenase from lamb kidney cortex

Glucose-6-phosphate dehydrogenase is the key regulatory enzyme of the pentose phosphate pathway and one of the products of this enzyme; NADPH has a critical role in the defence system against the free radicals. In this study, glucose-6-phosphate dehydrogenase from lamb kidney cortex kinetic properties is examined. The purification procedure is composed of two steps after ultracentrifugation for rapid and easy purification: 2′, 5′-ADP Sepharose 4B affinity and DEAE Sepharose Fast Flow anion exchange chromatography. Previously, we used this procedure for the purification of glucose-6-phosphate dehydrogenase from bovine lens. The double reciprocal plots and product inhibition studies showed that the enzyme obeys 'Ordered Bi Bi' mechanism: Km NADP+Km G-6-P and Ki G-6-P (dissociation constant of the enzyme-G-6-P complex) were found to be 0.018 ± 0.002, 0.039 ± 0.006 and 0.029 ± 0.005 mM, respectively, by using nonlinear regression analysis. The enzyme was stable at 4 °C for a week.