Characterization of the multiple forms of monoamine oxidase from chronic schizophrenic sera

Either half or one hour incubation time was enough to get a constant production of benzylaldehyde and were proportional to the amount of enzyme added. The optimal temperature of MAO, I, II, III, IV are 60 degrees, 37 degrees, 60 degrees, 45 degrees, and 37 degrees C respectively, and they follow Arrhenius equation until these optimal temperatures. Each form have optimal pH depends on substrate concentration used and the buffer used. These forms were shown to be inhibited by high substrate concentration with formation of inactive enzyme-amine complex, whereas butyl- and octylamine was found to be competitive inhibitors. Isoniazid inhibit MAO II, III, IV and V forms in a non competitive fashion, whereas MAO I inhibited competitively with respect to the substrate. Semicarbazid inhibit MAO I. III, IV and V forms in a non competitive fashion, whereas MAO II inhibited competitively with respect to the substrate.