Activity of some dehydrogenase enzymes in mitochondria from Physarum polycephalum.
1. Coupled mitochondria were isolated from exponentially growing Physarum polycephalum. 2. Activity of malate dehydrogenase (oxalacetate reduction) was 10.9 mumol/min/mg protein; the apparent Km was 64 microM. 3. The activity of NADP-isocitric dehydrogenase (IDH) was 110 nmol/min/mg with apparent Km of 35 microM. 4. NAD-IDH showed allosteric properties with AMP as a positive modulator. The apparent Km for the unmodulated activity, 2 mM, was decreased to 0.95 mM by 0.13 mM AMP. 5. Succinic dehydrogenase activity was estimated as three times higher than that of alpha-glycerophosphate dehydrogenase. 6. Mitochondria contained significant amounts of phenolic compounds. Protein estimation by the Bradford method is recommended.
D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology*; D010088:Oxidoreductases / Q000378:metabolism*; D010804:Physarum / Q000201:enzymology*; D013385:Succinate Dehydrogenase / Q000378:metabolism
D010088:Oxidoreductases; D005993:Glycerolphosphate Dehydrogenase; D008291:Malate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D013385:Succinate Dehydrogenase