The purification and characterization of L-malate : NAD oxidoreductase in Physarum polycephalum

Two isoenzymes of malate dehydrogenase could be demonstrated for plasmodia of Physarum polycephalum by polyacrylamide gel electrophoresis. The more cathodal form is uniquely associated with mitochondria (M-MDH) while the other form is found in the soluble cytoplasm (S-MDH). The isoenzymes are separated by acetone fractionation of soluble plasmodial homogenates acidified to pH 5.0. The M-MDH is purified 176-fold by cetylpyridinium chloride treatment, fractionation with ammonium sulfate, and gradient elution from sulfoethyl cellulose at pH 6.0. The S-MDH is purified 123-fold by ammonium sulfate fractionation, diethylaminoethyl cellulose chromatography, and gradient elution from sulfoethyl cellulose at pH 5.5. Both isoenzymes could be further characterized by chemical and physical parameters. [...]Biology and Biochemistry, Department o