Possible isoenzymes of monoamine oxidase in rat tissues

1968 ◽  
Vol 46 (4) ◽  
pp. 295-297 ◽  
Author(s):  
H. C. Kim ◽  
A. D'Iorio
Keyword(s):  
Monoamine Oxidase ◽  
Rat Liver ◽  
Oxidase Activity ◽  
Liver Homogenate ◽  
Rat Tissues ◽  
Consistent Difference ◽  
Monoamine Oxidase Activity ◽  
Mitochondrial Monoamine Oxidase

The solubilized monoamine oxidase activity of rat liver, kidney, and brain can be separated into several bands by cellulose polyacetate membrane electrophoresis. Four such bands of activity are found in the whole liver homogenate while mitochondrial and microsomal fractions appear to have two. The activity of these bands has been assayed using three different substrates, isoamylamine, tyramine, and benzylamine. The solubilized mitochondrial monoamine oxidase activity of kidney and brain when submitted to electrophoresis is found to separate in two fractions. There is some small but consistent difference of distribution of activity when using different substrates.

On hepatic mitochondrial monoamine oxidase activity in lipid deficiency

1979 ◽  
Vol 57 (6) ◽  
pp. 588-594 ◽  
Author(s):  
C. Kandaswami ◽  
A. D'Iorio
Keyword(s):  
Fatty Acids ◽  
Monoamine Oxidase ◽  
Oxidase Activity ◽  
Marked Decrease ◽  
Specific Activity ◽  
Essential Fatty Acids ◽  
Mitochondrial Outer Membrane ◽  
Monoamine Oxidase Activity ◽  
Membrane Enzyme ◽  
Mitochondrial Monoamine Oxidase

A marked decrease in liver mitochondrial monoamine oxidase activity was noticed in rats fed a fat-free diet as compared with that of their controls. In lipid-deprived rats, the specific activity of this enzyme was very low towards different substrates studied. The activity of kynurenine 3-monooxygenase, which like monoamine oxidase is localized on the mitochondrial outer membrane, was similarly depressed under conditions of lipid deprivation. On the other hand no major changes were observed in the activity of the inner membrane enzyme, kynurenine aminotransferase. Mitochondria from fat-free diet-fed rats were deficient in essential fatty acids whereas no appreciable variations were found in the relative proportions of phospholipids in comparison with those of control mitochondria. Mitochondrial monoamine oxidase activity of the deficient rats retained its sensitivities to inhibitor drugs like clorgyline and deprenyl. No changes were noticeable in the substrate specificity of monoamine oxidase in these rats. When we switched the fat-free diet-fed rats to a diet supplemented with a source of essential fatty acids, there was an elevation in the activities of both monoamine oxidase and kynurenine 3-monooxygenase, their levels approaching those of the control rats.

scholarly journals A kinetic evaluation of monoamine oxidase activity in rat liver mitochondrial outer membranes

1974 ◽  
Vol 139 (3) ◽  
pp. 645-652 ◽  
Author(s):  
Miles D. Houslay ◽  
Keith F. Tipton
Keyword(s):  
Monoamine Oxidase ◽  
Rat Liver ◽  
Oxidase Activity ◽  
Monoamine Oxidase Activity ◽  
Irreversible Inhibitor ◽  
Kinetic Evaluation ◽  
Reversible Inhibitors ◽  
Substrate Specificities ◽  
Outer Membranes ◽  
Enzyme Species

1. A preparation of mitochondrial outer membranes from rat liver can be shown to contain two kinetically distinct monoamine oxidase activities. These activities are distinguishable by their different sensitivities to the irreversible inhibitor clorgyline, and by the effect of the reversible inhibitors benzyl cyanide and 4-cyanophenol. 2. The substrate specificities of the preparation and the two enzyme species have been elucidated.

Polyacrylaniide Gel Electrophoresis of Rat Liver Mitochondrial Monoamine Oxidases

1973 ◽  
Vol 51 (7) ◽  
pp. 1089-1095 ◽  
Author(s):  
J. M. Diaz Borges ◽  
A. D'Iorio
Keyword(s):  
Monoamine Oxidase ◽  
Rat Liver ◽  
Gel Electrophoresis ◽  
Oxidase Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Liver Mitochondria ◽  
The Other ◽  
Rat Liver Mitochondria ◽  
Monoamine Oxidase Activity ◽  
Tetrazolium Staining

Solubilized rat liver mitochondria were subjected to polyacrylamide gel electrophoresis. The monoamine oxidase activity was localized directly on the gel with radioactive substrates (serotonin, benzylamine, and tyramine). Serotonin and tyramine monoamine oxidase activity separated in several bands which migrated to the anode and cathode whereas benzylamine activity was localized in one band. This band was demonstrated only when the electrophoresis was run from cathode to anode. Each one of tyramine and serotonin activities could be found devoid of the other two activities. Benzylamine activity could be separated from the serotonin activity though not from the tyramine activity. The detection of monoamine oxidase with the tetrazolium staining provided a localization of the enzyme activity which was different from that observed using radioactive substrates. These results, in accordance with those previously obtained by us with sucrose gradient electrophoresis of the same preparation, support the existence of different enzymes for the oxidative deamination of benzylamine and serotonin. On the other hand our results did not eliminate the possibility of overlapping substrate specificity of tyramine activity with those of serotonin and benzylamine activities.

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