The purification and properties of NADP-dependent isocitrate dehydrogenase from ox-heart mitochondria

The purification of NADP-linked isocitrate dehydrogenase from ox heart mitochondria is described. The molecular weight from gel filtration, sedimentation equilibrium and gel electrophoresis is 90000+/-4000, and there are two subunits in the molecule each of which binds NADPH with enhancement of the coenzyme fluorescence. The amino-acid composition is reported, and the absorption coefficient, A1/280%, estimated from dry weight measurements is 11.8 cm-1.