The presence of unsedimentable forms of monoamine oxidase (EC 1.4.3.4) in liver and brain homogenates has prompted fresh studies on the effects of inhibitors on this cytosolic monoamine oxidase. Clorgyline is a specific monomine oxidase A inhibitor and (−)-deprenyl and MDL 72145 are specific monoamine oxidase B inhibitors. We investigated the effects of (−)-deprenyl, MDL 72145 and clorgyline on the purified enzyme from mitochondria and cytosolic monoamine oxidase along with high speed cytosol and 1% Triton X-100 treated mitochondrial preparations. Clorgyline enhanced the activity of the purified enzyme several-fold. (−)-Deprenyl and MDL 72145 also enhanced and inhibited the activity of cytosolic monoamine oxidase in a concentration-dependent manner.
