Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Incubation of aldehyde dehydrogenase-free mitochondrial preparations with biogenic amines serotonin, tyramine, 2-phenylethylamine and 5-methoxytryptamine resulted in inhibition of enzymes activity of both outer (rotenone-insensitive NADH-cytochrome c reductase) and inner (succinate dehydrogenase, succinate cytochrome c reductase) mitochondrial membranes. Solubilization of mitochondria after the incubation did not influence the amine-induced alteration of succinate dehydrogenase activity. Pretreatment of the organelles with a mixture containing chlorgyline and deprenyl completely inhibited monoamine oxidase (MAO) activity and prevented the effects of all the amines studied on mitochondrial enzymes. MAO-dependent effects of 5-methoxytryptamine were fully reproduced by 5-methoxyindolyl-3-acetaldehyde (one of probable products of 5-methoxytryptamine deamination). The effect of the aldehyde was not prevented by chlorgyline and deprenyl. After selective inhibition of MAO-A by chlorgyline the order of MAO-B-dependent effects of biogenic amines on mitochondrial enzymes studied was as follows: tyramine greater than or equal to 2-phenylethylamine much greater than serotonin. In deprenyl pretreated mitochondria the potency of MAO-A-dependent effects of these amines was: serotonin greater than tyramine much greater than much greater than 2-phenylethylamine. The data obtained suggest that the product(s) of oxidative deamination of biogenic amines (probably the aldehydes) catalyzed by both types of MAO (MAO-A and MAO-B) are able to regulate the energy functions of mitochondria.
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PMID:[The role of monoamine oxidase in the regulation of mitochondrial energy functions]. 175 90

Monoamine oxidase (MAO) activity (substrate: tyramine) has been studied in rat intestinal wall mitochondrial fractions identified by monitoring succinate dehydrogenase and cytochrome oxidase activities. The MAO activity, which was not due to contamination with mitochondria, has been also found in nuclear and microsomal (+hyaloplasm) fractions. Deamination of tyramine, serotonin and dopamine by rat intestinal mitochondrial MOA obeyed the Michaelis--Mentern kinetics. The Vmax values were the highest for deamination of tyramine, the lowest--for norepinephrine. The lowest Km value was recorded in the systems with 2-phenylethylamine. Data on the inhibitory effect of low concentrations of deprenyl suggest that 50% of the total tyramine deaminating activity in rat intestinal mitochondria was due to presence of MAO type B. Low concentrations of chlorgyline inhibited the deamination of tyramine in these systems by 20-30% suggesting a possibility of presence in the rat intestinal mitochondria of a tyramine deaminating activity distinct from MAO type A. Pyrazidol or harmine, which are selective inhibitors of the MAO type A, caused only partial (30-40%) inhibition of MAO activity (substrate: tyramine) in rat intestinal mitochondria. Controlled heating experiments indicated higher thermostability of MAO type B (substrate: 2-phenylethylamine) as compared with MAO type A (substrate: serotonin) in rat intestinal mitochondria. The data obtained suggest that rat intestinal mitochondria, contrary to human intestinal mucosa (cf. ref. 2), contain about 50% of MAO type B, which is comparatively thermostable and does not resemble in this respect the MAO type B in many other biological sources.
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PMID:[Properties of intestinal monoamine oxidase in the rat]. 708 Apr 82