[Comparative enzymological study of catalytic properties of sturgeon fish liver monoamine oxidases].

We performed comparative study of substrate and inhibitor specificity of liver monoamine oxidases (MAO) of the giant sturgeon Huso huso, starred sturgeon Asipenser stellatus, Persian sturgeon Asipenser persicus, and Russian sturgeon Asipenser gueldenstaedtii. Results of the substrate-inhibitor analysis with use of inhibitors chlorgilin and deprenil, as well as of five specific substrates indicate homogeneity of these enzymes. All studied MAO have several orders higher sensitivity to chlorgilin than that to deprenil, the essential interspecies differences being observed.

[The reactivity of liver monoamine oxidase in the ringed seal Phoca hispida ladogensis].

The goal of the work consisted in study of substrate and inhibitor specificity of liver monoamine oxidase (MAO) of the freshwater Ladoga subspecies of the ringed seal Phoca hispida ladogensis. The studied enzyme has been established to have large substrate specificity by deaminating, apart from eight classic substrates of MAO of terrestrial mammals, also histamine, the diamine oxidase substrate. It is found out that the deamination rates of benzylamine, beta-phenylethylamine, and N-methylhistamine almost one order higher than rates of deamination of serotonin and noradrenaline.

[Liver monoamine oxidase activity of the lamprey Lampetra fluviatilis. the substrate-inhibitory specificity].

Based on data of substrate-inhibitory analysis with use of specific inhibitors--deprenyl, chlorgi-lin--and specific substrates--serotonin, noradrenalin, benzylamine, beta-phenylethylamine, and N-methylhistamine--a suggestion is put forward about the possible existence of one molecular form of monoamine oxidase (MAO) in liver of mature individuals of the European lamprey Lampetra fluviatilis. There are determined kinetic parameters of monoamine oxidase deamination of eight substrates, which indicates the large spectrum of substrate specificity of the lamprey liver MAO. The studied enzyme does not deaminate histamine and putrescine and is not sensitive to 10(-2) M semicarbaside.

[Substrate-inhibitory analysis of monoamine oxidase from hepatopancreas of the octopus Bathypolypus arcticus].

Study of the substrate-inhibitory specificity of mitochondrial monoamine oxidase (MAO) of hepatopancreas of the octopus Bathypolypus arcticus revealed distinctive peculiarities of catalytic properties of this enzyme. The studied enzyme, on one hand, like the classic MAO of homoiothermal animals, is able to deaminate tyramine, serotonin, benzylamine, tryptamine, beta-phenylethylamine, while, on the other hand, deaminates histamine and does not deaminate putrescine--classic substrates of diamine oxidase (DAO). Results of the substrate-inhibitory analysis with use of chlorgiline and deprenyl are indirect proofs of the existence in the octopus hepatopancreas of one molecular MAO form.

[Catalytic characteristics of monoamine oxidase of whitefish Coregonus lavaretus ludoga].

Study of substrate-inhibitory specificity of liver mitochondrial monoamine oxidase (MAO) of sexually mature individuals of the whitefish Coregonus lavaretus ludoga P. from the Ladoga Lake has revealed distinguished peculiarities of catalytical properties of this enzyme. The studied MAO, on one hand, like the classical enzyme of homoiothermal animals, is able to deaminate tyramine, serotonin, benzylamine, tryptamine, and beta-phenylalanine, but, on the other hand, to deaminate histamine, the classic substrate of diamine oxidase.