Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The behavior of cytoplasmic and mitochondrial enzymes has been studied in rat liver at 1, 5, and 24 hr after 60 min of ischemia using histochemical methods. This period of ischemia resulted 24 h after ischemia in liver cell necrosis in about 15% of the volume of the ischemic liver lobes. As early as after 1 hr reperfusion lactate dehydrogenase (LDH, cytoplasm) activity decreased in a certain proportion of the liver parenchymal cells, whereas glutamate dehydrogenase (GDH, mitochondrial matrix) activity started to decrease after 5 hr reperfusion; the activities of mitochondrial membrane enzymes, monoamine oxidase and succinate dehydrogenase, did not decrease before 24 hr of reperfusion. It has been concluded that the early decrease in LDH activity is caused by leakage into the blood and reflects reversible damage; when this decrease is accompanied by a decrease in GDH activity irreversible liver cell damage is assumed. Diminished activity of mitochondrial membrane enzymes, due to leakage and denaturation, is observed when real necrosis can be assessed.
Exp Mol Pathol 1987 Dec
PMID:Changes in cytoplasmic and mitochondrial enzymes in rat liver after ischemia followed by reperfusion. 367 63

Two forms of monoamine oxidase (MAO A and MAO B) exist which, although similar in a number of properties, can be distinguished on the basis of their substrate specificity, inhibitor sensitivity, kinetic parameters, and protein structure. These properties were used to study the molecular mechanism(s) by which glucocorticoid hormones and "aging," known to alter MAO activity in vivo, regulated the expression of MAO A and MAO B in cultured human skin fibroblasts. The addition of dexamethasone or hydrocortisone to cultures resulted in a dose- and time-dependent increase in total MAO activity, whereas the removal of hormone from cultures resulted in a time-dependent decrease in activity toward control levels. The response to dexamethasone was affected by culture conditions such as serum concentration, feeding frequency, and cellular "age." Cellular aging, in the absence of hormone, also resulted in increased levels of total MAO activity. The effects of hormones and aging on total MAO activity appeared to be selective for MAO A. The 6- to 14-fold increases in total activity were paralleled by similar increases in the activity and amount of active MAO A but less than 2- to 3-fold increases in the activity and amount of MAO B. Altered synthesis or degradation of the active enzyme appeared to account for the effects of hormones, aging, and various culture conditions on MAO activity. Inhibitor sensitivity, substrate affinity, electrophoretic mobility, and molecular turnover number of either form of the enzyme were not altered during dexamethasone treatment or during cellular aging. However, rates of active MAO synthesis were affected by hormone treatment and feeding frequency, rates of active MAO degradation by serum concentration, and rates of active MAO synthesis or degradation by aging. In summary, we have shown that glucocorticoids and cellular aging selectively affect the amount of MAO A at the level of active enzyme synthesis or degradation. Further, our finding that the expression of the two forms of MAO in human fibroblasts can be independently regulated supports the growing evidence that MAO A and MAO B are separate molecular entities.
Cell Mol Neurobiol 1986 Jun
PMID:Monoamine oxidases A and B are differentially regulated by glucocorticoids and "aging" in human skin fibroblasts. 373 Dec 13

In the isolated, perfused rat heart, lipid peroxidation, induced by cumene hydroperoxide (Cum OOH), is accompanied by the release of malondialdehyde (MDA). Using a modified perfusion technique resulting in the separate collection of coronary and interstitial effluent, it can be shown that upon Cum OOH (0.5 mM) perfusion there is an immediate release of MDA in the coronary effluent and a delayed release in the interstitial fluid, indicating the susceptibility and coronary vascular tissue towards free radical-induced lipid peroxidation. Perfusion with Cum OOH leads to an initial increase of the coronary flow and a depressed contractility followed by a cardiac arrest concomitantly with the onset of MDA release in the interstitial fluid. Finally, during prolonged perfusion the coronary flow diminishes and contracture of the heart muscle ('stone heart') develops. These phenomena resemble those occurring during the 'calcium paradox'. Although the contractility diminishes immediately after the perfusion with Cum OOH the tissue ATP level and energy charge (formula; see text) remain constant. From the moment of cardiac arrest the ATP and creatine phosphate levels gradually decrease and the energy charge drops simultaneously with the appearance of MDA in the interstitial fluid. In contrast to the calcium paradox there is no simultaneous increase in the myocardial AMP level. Various mitochondrial enzymes (cytochrome c oxidase, monoamine oxidase, carnitinepalmitoyltransferase I and palmitoyl CoA synthetase) were tested and not affected by Cum OOH perfusion. During the development of contracture after 20 min of Cum OOH perfusion massive contraction band necrosis of cardiac tissue occurs. However, overall protein release is lower when compared with the protein release during the calcium paradox.(ABSTRACT TRUNCATED AT 250 WORDS)
J Mol Cell Cardiol 1985 Jul
PMID:Studies on cumene hydroperoxide-induced lipid peroxidation in the isolated perfused rat heart. 402 Aug 83

Discriminant analysis was used to discriminate between Reye syndrome (RS) patients and non-RS cases based either on conventional blood chemistry data obtained upon admission, or on the activities of hepatic mitochondrial enzymes in biopsy or necropsy tissue. The control group for blood chemistry measurements contained children with upper respiratory tract infections, varicella, etc. who did not develop RS, as well as healthy children. Subjects with no liver disorder (e.g., accidental death, sudden infant death, etc.) or with non-RS liver disorders were used as controls for hepatic enzyme studies. Hepatic damage indicators (aspartate aminotransferase, AST; alanine aminotransferase, ALT; and bilirubin) correctly classified 86-96% of non-RS cases and 61-71% of RS. By contrast, AST and ALT had little prognostic value (63% overall correct). Ammonia effectively classified favorable outcome cases (95% correct) but not unfavorable (14% correct). However, when ammonia was included with stage of coma information 88% of the favorable and 85% of the unfavorable outcome cases were correctly classified. Discriminant analysis of hepatic enzymes (glutamate dehydrogenase and monoamine oxidase activity) for a RS and a non-RS group correctly classified 80% of non-RS and 95% of RS specimens. The function was suitable for the direct evaluation of RS-like mitochondrial enzyme changes in rat liver.
Exp Mol Pathol 1985 Oct
PMID:Prognosis and diagnosis of Reye syndrome by discriminant analysis. 404 46

The conversion of cyclohexanecarboxyl-CoA to hippuric acid in submitochondrial fractions from guinea pig liver was studied using a gas chromatographic-mass spectrometric method employing selected ion monitoring. Comparison of the activities of the cyclohexanecarboxyl-CoA to hippuric acid converting system (CCoAHC-system) and marker enzymes in the various submitochondrial fractions showed that the CCoAHC-system is localized in the mitochondrial matrix. Partial separation of the inner and outer membranes has been accomplished by treating mitochondria with digitonin in isotonic medium and fractionating the treated mitochondria by differential centrifugation. A digitonin-protein ratio of 2.6 mg of digitonin/10 mg of protein must be used in order to release significant amounts of amine oxidase activity (outer membrane marker) from low speed mitochondrial pellets. This pellet still contained most of the glutamate dehydrogenase activity and was insignificantly contaminated with adenylate kinase. Moderate concentrations of phenazine methosulfate (PMS) greatly stimulated the activity of the CCoAHC-system, even in intact mitochondria (optimal concentration of PMS: 1 mM) whilst higher concentrations (greater than 1 mM) decreased the activity. The formation of hippuric acid in these mitochondrial preparations was linear with time for at least 40 min and linear with respect to protein concentration up to approximately 2.0 mg mitochondrial protein X ml-1.
Mol Cell Biochem 1985 Jul
PMID:The aromatization of cyclohexanecarboxyl-CoA to hippuric acid by guinea pig liver mitochondria: submitochondrial localization. 404 29

We have isolated a mouse monoclonal antibody to human platelet monoamine oxidase (MAO) B. The antibody (MAO-1C2) was isolated from a fusion of mouse myeloma P3/X63 Ag8 to spleen cells from a BALB/c mouse immunized with a partially purified platelet preparation in which an estimated 21-31% of the protein was [3H]pargyline-labeled MAO B. The antibody indirectly immunoprecipitates both [3H]pargyline-labeled, catalytically inactive human MAO B, and unlabeled, catalytically active human MAO B. Binding of the antibody to MAO B has no detectable effect on catalytic activity. MAO-1C2 is specific for human MAO B, and fails to immunoprecipitate MAO A indirectly from human placenta or liver. Its ability to immunoprecipitate human MAO B but not MAO A from extracts of human liver provides a convenient technique for separating the two forms of the enzyme for comparative studies. The antibody does not recognize mouse liver MAO B, suggesting that the determinant is not universally expressed on MAO B from all species.
Mol Pharmacol 1982 Sep
PMID:A monoclonal antibody elicited to human platelet monoamine oxidase. Isolation and specificity for human monoamine oxidase B but not A. 618 72

Monoamine oxidase B (MAO B; EC 1.4.3.4) activity in detergent extracts of mitochondria from autopsy brain (gray matter and medulla), liver, lung, and kidney from a single individual and from pooled, human platelets could be immunoprecipitated by a monoclonal anti-human platelet MAO B antibody (MAO-1C2) in combination with appropriate secondary reagents. MAO A activity, which was detected in brain, liver, lung, and kidney, was not immunoprecipitated under the same conditions. All MAO B-containing extracts, regardless of tissue source, inhibited immunoprecipitation of [3H]pargyline-labeled human platelet MAO, and the shapes of the inhibition curves were identical. The concentration of immunologically detectable MAO B protein in the extracts was estimated from immunoprecipitation competition data by reference to a standard curve relating observed inhibition of immunoprecipitation to the concentration of catalytically active platelet MAO added (estimated from [3H]pargyline binding data). MAO B protein concentrations measured by this radioimmunoassay were similar to concentrations of active MAO B as measured by pargyline binding. These results demonstrate that in the brain and peripheral tissues studied, molecules with MAO B activity share a unique antigenic determinant and similar catalytic efficiency. They also extend previous observations that MAO B molecules extracted from mitochondria bear an antigenic determinant which is not present on MAO A molecules. These results demonstrate the validity of a new competitive radioimmunoassay for active plus inactive MAO B concentration in human platelet extracts and extracts of mitochondria from human tissues. This radioimmunoassay should complement [3H]pargyline binding assays and enzyme activity assays in studies designed to clarify the mechanisms of genetic, disease, and treatment factors which lead to differences in MAO B function among individuals.
Mol Pharmacol 1983 Jul
PMID:Use of a monoclonal antibody for comparative studies of monoamine oxidase B in mitochondrial extracts of human brain and peripheral tissues. 619 Nov 93

Inhibition of pineal monoamine oxidase (MAO) activity either by harmine or pargyline in adult male Sprague-Dawley rats housed in a 12 : 12 LD cycle resulted in increase pineal N-acetyltransferase (NAT) activity. Pineal MAO inhibition also increased pineal melatonin content, presumably as a result of the increased NAT activity. Conjunct treatment with propranolol, a beta-adrenergic receptor antagonist, nullified these effects, regardless of the MAO inhibitor (harmine, pargyline or both) used or the inhibitor dose given. MAO inhibition during continuous light resulted in increased NAT activity greater than that observed following MAO inhibition during a 12 : 12 LD cycle. On the other hand, the increase in melatonin content following MAO inhibition during continuous light was not significantly different from that following MAO inhibition during a 12 : 12 LD cycle. Conjunct propranolol administration negated the effects of MAO inhibition on both the level of NAT activity and melatonin content, regardless of the lighting conditions. The level of pineal NAT activity is apparently regulated by the level of pineal beta-adrenergic receptor stimulation. While melatonin production appears to be dependent on increases in NAT activity, biosynthesis of this methoxyindole may also be regulated, in part, by other factors or processes in metabolic pathway.
Mol Cell Endocrinol 1982 Mar
PMID:Regulation of rat pineal melatonin synthesis: effect of monoamine oxidase inhibition. 627 62

Selective inactivation of the multiple forms of mitochondrial monoamine oxidase (MAO) by proteases in intact and hypotonically disrupted rat liver mitochondria has been used to examine the question of differential membrane orientations of the A and B enzymes. Proteases used as probes included trypsin, beta-chymotrypsin, and the extracellular protease of Staphylococcus aureus, chosen for their different amino acid specificities. With all three proteases, no changes in the relative rates of MAO-A and MAO-B inactivation were observed after disruption of the mitochondria. Trypsin and beta-chymotrypsin gave much faster rates of MAO-A inactivation in both intact and disrupted mitochondria. The selective effect of trypsin on MAO-A was also confirmed in human placental mitochondria, which possess only A-type activity. The effectiveness of hypotonicity in disrupting the outer membrane of the mitochondria was shown by rapid protease inactivation of an intermembrane space marker enzyme, adenylate kinase (EC 2.7.4.3). Contrary to some recent reports in the literature, these findings strongly suggest that the MAO-A and MAO-B multiple-form catalytic activities do not reside on opposite faces of the membrane.
Mol Pharmacol 1984 Jan
PMID:Proteases as probes of mitochondrial monoamine oxidase topography in situ. 636 8

The correlation between structures of chemicals and their inducibility for megamitochondrial formation was investigated. Since the chemical structure universal to the inducers of megamitochondria previously reported (cuprizone and isonicotinic acid derivatives) is the carbazoyl group (-CONHNH2), semicarbazide (NH2NHCONH2) was tested first. Then, hydrazine (NH2NH2) was tested, replacing the carbazoyl group of semicarbazide by an amino group (-NH2). The present study demonstrates that (1) megamitochondria were induced in mouse and rat hepatocytes by feeding the animals with a diet containing semicarbazide or hydrazine, suggesting that the carbazoyl group was not essential for megamitochondrial formation; (2) hydrazine-induced megamitochondrial formation was a reversible process. Coupling efficiencies and activities of ATPase and cytochrome oxidase of megamitochondria induced by hydrazine were slightly decreased, while the activity of monoamine oxidase was moderately decreased. Freeze-fracture electron microscopy revealed particle-free regions in the outer membranes of megamitochondria fixed with glutaraldehyde at 22 degrees C; the regions disappeared at 25 degrees C, indicating that the temperature of the liquid crystalline to gel state lipid phase transition in the megamitochondrial outer membrane was elevated. It is speculated that chemical structure of inducer of megamitochondria could be simplified to NH2-G (G, substituting group).
Exp Mol Pathol 1983 Oct
PMID:Induction of megamitochondria in the mouse and rat livers by hydrazine. 661 23


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