Further studies on the properties and assay of glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase of rat liver.

Renewed interest in the direct oxidative pathway of glucose 6-phosphate metabolism during the last few years has revealed that this pathway is by no means restricted to erythrocytes, yeast and microorganisms. The triphosphopyridine-nucleotide(TPN)-specific glucose 6-phosphate and 6-phosphogluconate dehydrogenases are also widely distributed in mammalian tissues (Dickens & Glock, 1950, 1951; Horecker & Smyrniotis, 1951), in a variety of lower plants and animals (Cohen, 1950) and also in higher plants (Conn & Vennesland, 1951; Gibbs, 1952). The significance of this pathway in animal tissues, its physiological control and the relative importance of the direct oxidative and glycolytic routes of carbohydrate metabolism are still, however, chiefly matters of conjecture. An essential preliminary step to such an investigation is to devise a satisfactory procedure for the assay of glucose 6-phosphate and 6-phosphogluconate dehydrogenases in animal tissues and it was with this object in view that the present work was undertaken.