Immunochemical localization of NADP-specific isocitrate dehydrogenase in Escherichia coli

The intracellular localization of isocitrate dehydrogenase was determined by immunochemical techniques with ultrathin sections of Escherichia coli. The thin sections, which were obtained by ultracryomicrotomy, were incubated first with antiserum specific for the enzyme and then with a protein A-gold complex. Transmission electron microscopy showed that the gold label was dispersed mainly in the cytoplasm.