Purification and Properties of a Nicotinamide Adenine Dinucleotide Phosphate-requiring Glyceraldehyde 3-Phosphate Dehydrogenase from Spinach Leaves

The glyceraldehyde 3-phosphate dehydrogenase which uses NADP+ and requires phosphate has been isolated from spinach leaves. The enzyme was shown to be pure by ultracentrifugation, polyacrylamide gel electrophoresis, and immuno gel diffusion. The enzyme was shown to have a molecular weight of about 600,000 based on sedimentation equilibrium centrifugation. The enzyme was shown to catalyze the oxidation of glyceraldehyde 3-phosphate by either NADP+ or NAD+ with the formation of 1,3-diphosphoglycerate. Results of studies with the two coenzymes indicate that they react with the enzyme at the same catalytic site.