6-Phosphogluconate dehydrogenase: Structural symmetry and functional asymmetry

Abstract: 6-Phosphogluconate dehydrogenase catalyzes the oxidative decarboxylation of 6-phosphogluconate to ribulose 5-phosphate through an oxidation, a decarboxylation and a tautomerization. The two subunits in the crystals of the dimeric sheep liver enzyme have the same conformation, as the apoenzyme and with the substrate or coenzyme. An hypothesis is now advanced that in solution, during catalysis, the two subunits have a different alternating role and thus a functional asymmetry.