Neurospora 6-Phosphogluconate Dehydrogenase

Abstract

Abstract A purification procedure is described for 6-phosphogluconate dehydrogenase (6-phospho-d-gluconate:NADP oxidoreductase (decarboxylating) EC 1.1.1.44) of Neurospora crassa. A 192-fold purification was obtained with a 30% yield and an average specific activity of 30. The purified enzyme has a molecular weight of 110,000 to 120,000 as estimated by gel filtration and consists of subunits of molecular weight 57,000. One or more reactive sulfhydryl groups influence the aggregation state of the enzyme, and are also essential for enzymatic activity as indicated by iodoacetamide inactivation. Kinetic parameters, specificity, heat stability, and inhibition by NADPH and fructose 1,6-diphosphate were measured as was photooxidation of the enzyme in the presence of Rose Bengal and pyridoxal phosphate.