[Inhibition of the activity of monoamine oxidases type A and B by derivatives of 2-propynylamine].

Inhibition by N-methyl-2-propynylamine derivatives (pargylline, deprenyl, chlorgyline indamanine) of monoamine oxidases (MAO) type Z (serotonin as a substrate) and type B (substrate: beta-phenylethylamine) in fragments of rat liver mitochondrial membranes was studied by means a kinetic method (15) which enables to detect and to evaluate quantitatively formation of intermediary dissociable enzyme-inhibitor complexes as well as to measure the rate of irreversible modification of these complexes (leading to the irreversible inhibition of MAO). The step of intermediary dissociable enzyme-inhibitor complex formation was involved in the processes of inhibition of mitochondrial MAO types A and B by all the 2-propynylamine derivatives studied. Rates of modification of these complexes into irreversibly inhibited forms of MAO types A and B in presence of different 2-propynylamine derivatives were of the same order of magnitude. But the values of the dissociation constants of the intermediary complexes for both MAO types differed dramatically with alterations of the substituents at the nitrogen atom in molecules of the 2-propynylamine derivatives which probably determines the well recognized properties of the 2-propynylamine derivatives of causing highly selective inhibition of oxidative deamination of various biogenic monoamines.