[Isolation, purification and the physicochemical properties of the monoamine oxidase from the myocardium]. / Vydelenie, ochistka i nekotorye fiziko-khimicheskie svoistva monoaminoksidazy iz serdechnoi myshtsy.

A preparation of monoamine oxidase, purified 20-fold with a yield of 20%, was isolated from mitochondrial fraction of bovine heart after treatment with a nonionic detergent Triton X-100 combined with sonication followed by gel filtration on Sephadex G-200 and Sepharose 6B. By the data of gel filtration molecular weight of the preparation was 330,000. Two protein fractions with molecular weights of 84,000 and 90,000 were found using disc electrophoresis in 7.5% polyacrylamide gel containing 2-mercaptoethanol and sodium dodecylsulfate. The purified enzyme contained 8.6 mol of SH-groups per 100,000 daltons of protein, 4.1 micrograms of inogranic phosphate per 1 mg of protein; Km value was 37.6 microM for benzylamine as a substrate. In experiments with elective inhibitors of monoamine oxidases the enzyme from bovine heart muscle exhibited high sensitivity to the inhibitory effect of deprenyl, which characterises the monoamine oxidases of the B type.

[Disorders of oxidative deamination of biogenic amines in the myocardium in experimental atherosclerosis]. / Narushenie okislitel'nogo dezaminirovaniia biogennykh aminov v serdechnoi myshtse pri éksperimental'nom ateroskleroze.

Statistically significant inhibition of oxidative deamination of several biogenic amines was found in mitochondrial fraction of heart muscle from rabbits and rats with experimental atherosclerosis and hypercholesterolemia, caused by various methods. Sensitivity of oxidative deamination of tryptamine to inhibitory effect of clorgyline (selective inhibitor of mitochondrial monoamine oxidases) was unaltered in rats with experimental hypercholesterolemia. The rate of oxidative deamination of beta-phenyl ethylamine, tryptamine, benzylamine as well as histamine and putrescine was inhibited after treatment of the mitochondrial fragments from healthy rabbit and rat heart muscles with preparations of oxidized linoleic and linolenic acids, concentration of which was increased in tissues under conditions of atherosclerosis.

[Properties of monoamine oxidases from myocardial mitochondria]. / O svoistvakh mitokhondrial'nykh monoaminoksidaz serdechnoi myshtsy.

Mitochondrial monoamine oxidases from rabbit and rat heart muscles varied distinctly in the sensitivity to the effect of selective irreversible inhibitors clorgyline and deprenyl. In presence of mitochondrial fragments from rabbit heart oxidation of phenylethylamine, tyramine, benzylamine and triptamine was highly sensitive to the effect of deprenyl. Very low concentrations of clorgyline inhibited oxidation of these amines in samples containing rat heart mitochondrial fragments. Rabbit heart mitochondrial fragments appear to contain considerable amounts of monoamine oxidases of "B" type and rat heart mitochondrial fragments--the monoamine oxidases of "A" type. A highly sensitive fluorescent method was used for estimation of the monoamine oxidase activity; it was based on the extinguishing by hydrogen peroxide in presence of peroxidase of the scopolethine fluorescence.

[Deamination of nitrogenous compounds in mitochondrial membranes under stimulation of lipid peroxidation]. / Dezaminirovanie azotistykh soedinenii v mitokhondrial'nykh membranakh pri stimuliatsii perekisnogo okisleniia lipidov

Fragments of mitochondrial membranes, obtained by freezing-thawing of mitochondrial fraction from rat liver homogenate, were treated with Fe2+ ions under conditions, which were optimal for accumulation of a product of lipid peroxidation--malondialdehyde (MDA). The accumulation of MDA in the mitochondrial membranes was accompanied by a decrease in deamination of monoamines (tyramine or, especially, tryptamine) and by appearance of qualitatively new properties to deaminate histamine or cadaverine as well as adenylic acid. Appearance of these properties was prevented by blocking with trans-2-phenylcyclopropylamine or N-methyl-N-benzylpropynylamine of the mitochondrial monoamine oxidase activity. Inhibitors of initiated by free radicals lipid peroxidation (propylgallate, butyl hydroxytoluene) did not bind Fe2+ ions but prevented the alterations in deamination of nitrogenous compounds induced by the treatment of the fragments of mitochondrial membranes with Fe2+ ions. Stimulation of lipid peroxidation in mitochondrial membranes was, thus, accompanied not only by partial inactivation of the structure-bound monoamine oxidase but also by apparent qualitative alteration (transformation) in its catalytic properties.