NADP+-specific isocitrate dehydrogenase of Excherichia coli. III. Two-step purification employing affinity chromatography.

The NADP+-specific isocitrate dehydrogenase (threo-DS-isocitrate:NADP+ oxidoreductase (decarboxylating), EC 1.1.1.42) of Excherichia coli has been purified to electrophoretic homogeneity by a two-step purification procedure employing affinity chromatography. The overall yield of enzyme was 30% with specific activity 125 mumol/min per ng protein. Electrophoretic homogeneity of the isocitrate dehydrogenase was deterimed in analytical polyacrylamide gels in a Tris/acetate/EDTA buffer system at pH 7.5 and in a citrate/phosphate buffer system at pH 6.0.