A simple assay for monoamine oxidase using glutathione peroxidase and glutathione reductase

A new fluorometric assay for the determination of monoamine oxidase activity that is applicable to any substrates including dopamine and serotonin is described. Hydrogen peroxide formed during the monoamine oxidase reaction was reduced in the presence of glutathione and glutathione peroxidase, and the oxidized glutathione was measured fluorometrically as NADP+ via oxidation of NADPH by glutathione reductase. This method was applied for inhibitor studies using clorgyline and deprenyl.