[Enzymological characteristics of liver monoamine oxidase of the skipjack tuna Katsuwonus pelamis].

There has been carried out a study of substrate and inhibitor specificity of the liver mitochondrial monoamine oxidase (MAO) of the striped-bellied tunny Katsuwonus pelamis. Results of the substrate-inhibitor analysis with use of chlorgilin and deprenyl are an indirect proof for the existence in the tunny liver of one molecular MAO form. The studied enzyme, like the liver MAO of terrestrial mammals, deaminates tyramine, tryptamine, dopamine, serotonin, noradrenalin, benzylamine, β-phenylethylamine, and N-methylhistamine, does not deaminate histamine and is not inhibited by 10 mM semicarbaside. Tacrine, acriflavine, proflavine, acridine orange, and pyronin G have been established to be irreversible inhibitors of intermediate strength with respect to the tunny liver MAO. Specificity of action of the inhibitors at deamination of different substrates was identical.