Abstract
The multiplicity of MAO in hog kidney mitochondria was studied by acrylamide gel electrophoresis. The mitochondrial MAO was solubilized with 0.1% Triton X-100. Km value was not changed by solubilization, but it was found that type A MAO was inhibited by Triton X-100. The gel was removed from the tube and incubated at 37°C for about 1 hr with a mixture of tetrazolium and tryptamine as substrate. Two bands showing MAO activity were detected. Both bands simultaneously vanished by treatment with deprenyl and pargyline. These results indicate that the two coloured bands were type B MAO. On the other hand, the hog kidney mitochondrial preparation was run. After electrophoresis, MAO activities of each slice were measured toward tryptamine as substrate. Two peaks were obtained. One was inhibited by pargyline and one was thought to be of type A MAO. Mobility of type B MAO was examined using 10-7M of [3H] -pargyline and it was found that the mobility of type A MAO differs from that of type B MAO. The molecular weight of these kidney mitochondrial MAO was found to be about 60, 000 and 140, 000. These results suggest that MAO in hog kidney mitochondria contains two types differing in mobility and major one is type B MAO and the molecular weight is about 60, 000 as minimum unit and composed of two protein subunits.
