The binding of [3H] pargyline to rat liver mitochondrial monoamine oxidase

The synthesis and purification of tritium labelled N-desmethylpargyline and pargyline are described. The suitability of these irreversible suicide inhibitors of monoamine oxidase (MAO) as ligands in binding studies to rat liver mitochondrial MAO has been evaluated. [3H] Pargyline was found to be more satisfactory than its N-desmethyl analogue because of its greater potency and lower proportion of non-specific binding. The binding of pargyline reached saturation when about 31 pmol mg protein-1 was bound. It was not possible to explain the time course of the binding by either simple first or second-order kinetics. [3H]-Pargyline is a potentially valuable ligand for the estimation of the concentration of NAO active centres without the need to remove the enzyme from the mitochondrial membrane.