The regulation of glucose 6-phosphate dehydrogenase from Dicentrarchus labrax (bass) liver

Abstract 1. 1. Kinetic constant values of the reaction catalyzed by bass liver glucose 6-phosphate dehydrogenase show to be modified between 10 and 40°C. 2. 2. The Arrhenius plot between 10 and 50°C shows two slopes with different activation energies. 3. 3. These results suggest a regulation of this enzyme by environmental temperature. 4. 4. Kinetics of ATP inhibition were examined between pH 6.2 and 7.8: patterns and K i values obtained are affected by the pH variation. 5. 5. NADH is an effective inhibitor of bass glucose 6-phosphate dehydrogenase but this enzyme does not show NAD-linked activity. 6. 6. Kinetics of pyridoxal 5′-phosphate inhibition have indicated the presence of a lysine in the catalytic site for NADP + .