Separation of malate dehydrogenase isoenzymes by affinity chromatography on 5'-AMP-Sepharose

The mitochondrial and glyoxysomal isoenzymes of malate dehydrogenase (EC 1.1.1.27) from watermelon cotyledons and the mitochondrial isoenzyme from pig heart adsorbed reversibly to 5'-AMP-Sepharose. They were specifically eluted with low concentrations of NADH rather than by NAD. In contrast, the cytoplasmic isoenzymes showed no affinity to the matrix-bound ligand. These binding properties are discussed in terms of structural and regulatory differences of the particulate and soluble malate dehydrogenase isoenzymes. Affinity chromatography on 5'-AMP-Sepharose significantly improved the purification of the particulate malate dehydrogenase isoenzymes with respect to homogeneity, yield, and the number of purification steps. In the case of the glyoxysomal isoenzyme it was the essential procedure to obtain complete purification of the enzyme.