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Query: EC:1.1.1.37 (malate dehydrogenase)
 4,591 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An increase in activity of several dehydrogenases of tricarboxylic acid cycle (NADP-dependent malate dehydrogenase, alpha-ketoglutarate dehydrogenase) was observed in rat liver tissue under conditions of acute hemorrhage. The enzymatic activity was slightly higher in the group of animals with relatively prolonged life-time as compared with those, which lived less than 4 hrs. Activity of cytochrome oxidase was inhilited in the both groups of animals (by 27% and 29%, respectively). The less distinct decrease in both temperature in the group of animals with prolonged life-time might maintain the rate of Krebs cycle substrates oxidation. Activation of respiration in liver tissue under conditions of the hemorrhage is considered as a compensatory reaction tending to improve oxygen utilization in hypoxia. At the same time, inhibition oy cytochrome oxidase demonstrates the impairment of electron transport and decreased rate of energy production in liver mitochondria.
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PMID:[Tissue respiratory enzymes in the rat liver in acute blood loss]. 22 69

NAD-dependent malate dehydrogenase (1.1.1.37) activity was markedly decreased under hypoxia in rat brain and liver mitochondria and cytoplasm; most significant decrease was observed in brain cortex mitochondria. NADP-dependent malate dehydrogenase (1.1.1.40) activity was also reduced under these conditions and the most considerable changes were found in liver mitochondria and cytoplasm. Distribution of activities of these enzymes between subcellular fractions of brain and liver did not change under hypoxia. The oxaloacetate level rised by 20% in brain and decreased by 20-25% in liver under hypoxia.
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PMID:[Change in the activity of NAD- and NADP-specific malate dehyrdogenases in oxygen deficiency in different tissues]. 23 74

With respect to the enzymes of NADPH-forming metabolic pathways in human leukocytes: (a) Glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase (decarboxylating) were less active in leukocytes (mostly myeloblasts) from eight patients with acute myeloblastic leukemia (I) than in leukocytes (mostly granulocytes) from 16 normal subjects (II). (b) Of the enzymes of the citrate cleavage pathway, ATP citrate lyase and malate dehydrogenase (decarboxylating) (NADP+) were virtually absent in the cells studied. (c) Isocitrate dehydrogenase (NADP+), aspartate aminotransferase, and alanine aminotransferase, which, together with the much more active malate dehydrogenase, constitute a newly proposed NADPH-forming metabolic cycle, showed a higher activity in I than in II or III, and therefore could compensate, as concerns NADPH-generation, for the low activity of pentose cycle dehydrogenases. We are not sure whether the enzymatic characteristic of I cells is attributable to their immaturity or to their leukemic nature.
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PMID:Enzyme activities of NADPH-forming metabolic pathways in normal and leukemic leukocytes. 23 46

Administration of triamcinolone or dexamethasone to rats led to a prompt, marked and persistent rise in liver acetyl-CoA carboxylase activity. The activity of fatty acid synthetase increased to a lesser extent and after a more prolonged glucocorticoid treatment, whereas the changes in that of NADP-malate dehydrogenase and ATP-citrate lyase were not appreciable. The overall channeling of [1-14-C]acetyl-CoA to fatty acids was enhanced. The triamcinolone effect on acetyl-CoA carboxylase activity appeared to be dependent on the coincident hyperinsulinemia since it was not obtained in alloxan-diabetic rats, whereas the alanine-aminotransferase-inducing effect of this hormone was additive to that of insulin deficiency. In adipose tissue triamcinolone treatment caused a reduction in the activity of all lipogenesis enzymes and blunted their response to insulin administration. The antagonism of glucocorticoids toward insulin, selectively modulating the responses of the insulin-sensitive enzymes in liver and adipose tissue is discussed. The rise in hepatic lipogenic capacity, through the retention of the ability of insulin to induce acetyl-CoA carboxylase, may be physiologically important in restraining the ketogenesis from acetyl-CoA despite the increased fat utilization during glucocorticoid excess.
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PMID:Modulation of the activity of insulin-dependent enzymes of lipogenesis by glucocorticoids. 23 62

The segmentation of the proximal tubules in the kidney of the female rat was studied by means of enzyme histochemical reactions and the results compared with those observed in male and recently described by Jacobsen and J0rgensen (1973 a). Reactions were performed for the following soluble, coezyme-dependent oxido-reductases: glucose 6-phosphate dehydrogenase, alpha-glycerophosphate dehydrogenase, 3 alpha-hydroxysteroid dehydrogenase, NAD-as well as NADP-dependent isocitrate dehydrogenases, NAD-dependent malate dehydrogenase, NADP-dependent, decarboxylating malate dehydrogenase, uridine diphosphate glucose dehydrogenase. Measures were taken to reduce enzyme diffusion and eliminate interference from tissue tetrazolium reductases. Furthermore, reactions were performed for a number of less soluble or insoluble enzymes: glucose 6-phosphatase, mitochondrial alpha-glycerophosphate dehydrogenase, beta-hydroxybutyrate dehydrogenase, succinate dehydrogenase and tetrazolium reductases. In the proximal tubules of the female rat all enzymes studied--except beta-hydroxybutyrate dehydrogenase--showed segmental differences, most of them clearly revealing three segments. Sex differences were found concerning all enzymes except uridine diphosphate glucose dehydrogenase and NADP-dependent isocitrate dehydrogenase. The most pronounced sex-related differences were seen in the third segment in which part the male rat showed highest activity in respect to tetrazolium reductases, NAD-dependent isocitrate dehydrogenase, succinate dehydrogenase, beta-hydroxybutyrate dehydrogenase, 3 alpha-hydroxysteroid dehydrogenase and glucose 6-phosphate dehydrogenase and the female in respect to glucose 6-phosphatase, alpha-glycerophosphate dehydrogenases, and NADP-dependent, decarboxylating malate dehydrogenase. A few of the enzymes exhibited minor sex differences in the first two segments.
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PMID:Enzyme histochemical observations on the segmentation of the proximal tubules in the kidney of the female rat. 23 55

Improved histochemical techniques for the demonstration of NADP+-specific isocitrate dehydrogenase and malate dehydrogenase in tissue sections are described. With these techniques a semipermeable membrane is interposed between the incubating solutions and the tissue sections preventing diffusion of enzymes into the medium during incubation. In the histochemical system the NADP+-dependent enzymes catalyze the electron transfer from threo-Ds-isocitrate or L-malate into NADP+. Phenazine methosulphate and menadione serve as intermediate electron acceptors between reduced coenzyme and nitro-BT. Sodium-azide and amytal are incorporated into the incubating-medium to block electron transfer to the cytochromes. For demonstrating enzyme activities in sections containing non-specific alkaline phosphatase, a phosphatase inhibitor is added into the incubation media. Problems involved in the histochemical demonstration of both enzymes are discussed.
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PMID:Semipermeable membranes for improving the histochemical demonstration of enzyme activities in tissue sections. V. Isocitrate: NADP+ oxidoreductase (decarboxylating) and malate: NADP+ oxidoreductase (decarboxylating). 23 22

Rat and calf adrenal cortex homogenates were found to contain three different malic enzymes. Two were strictly NADP+-dependent and were localized, one each, in the cytosol and the mitochondrial fractions, respectively. These two enzymes appear to be identical to those described by Simpson and Estabrook (Simpson, E. R., and Estabrook, R. W. (1969) Arch. Biochem. Biophys. 129, 384-395). The third was NAD(P)+-linked and was present in the mitochondrial fraction only. All three malic enzymes separated as distinct bands during electrophoresis on 5 percent polyacrylamide slab gels at pH 9.0. Marker enzymes and the mitochondrial malic enzymes migrated together in intact mitochondria during sucrose density gradient centrifugations despite changes in the equilibrium position of the mitochondria promoted by energy-dependent calcium phosphate accumulation. In adrenal cortex mitochondria subfractionated by the method of Sottocasa et al. (SOTTOCASA, G.L., KUYLENSTIERNA, B., ERNSTER, L., and BERGSTAND, A. (1967) J. Cell Biol. 32, 415-438), both malic enzymes were associated with the inner membrane-matrix space. Sonication solubilized the two malic enzymes along with the matrix space marker enzymes. The NAD(P)+-dependent malic enzyme was purified 100-fold from calf adrenal cortex mitochondria. The final preparation was free of malic dehydrogenase, fumarase, the strictly NADP+-linked malic enzyme and adenylate kinase. Either Mn24 orMg2+ was required for activity and 1 mol of pyruvate was formed for each mole of NAD+ and NADP+ reduced. The pH optima with NAD+ and NADP+ were 6.5 tp 7.0 and 6.0 to 6.5, respectively. Michaelis-Menten kinetics were observed on the alkaline side. Fumarate, succinate, and isocitrate were positive and ATP and ADP were negative modulators of the regulatory enzyme. The modulators did not influence the stoichiometry and they were not metabolized during the reaction. Under Vmax conditions the ratios for the rate of NAD+:NADP+ reduction were 1.76 and 1.15 at pH 7.4 and 6.0, respectively. The apparent Michaelis constants also differed depending on the pH and the coenzyme. At pH 7.4 (in the presence of 5 mM fumarate) and at pH 6.0 (no fumarate) the Km values for (-)-malate, NAD+, and Mn2+ were 1.7, 0.16, and 0.15 mM, and 0.31, 0.06, and 0.09 mM, respectively. At pH 7.4 (5MM fumarate) and pH 6.0 (no fumarate), the Km values for (-)-malate, NADP+, and Mn2+ were 6.5, 0.62, and 0.59 mM, and 0.68. 0.12, and 0.31 mM, respectively. The apparent Ki values for ATP with NAD+ and NADP+ as coenzyme were 0.42 and 0.27 mM, respectively.
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PMID:The mitochondrial malic enzymes. I. Submitochondrial localization and purification and properties of the NAD(P)+-dependent enzyme from adrenal cortex. 23 89

1. Measurements are presented of the activity and intracellular distribution of phosphoenolypruvate carboxykinase, pyruvate carboxylase and NADP-malate dehydrogenase in rat, guinea-pig and rabbit liver and kidney cortex, together with previously obtained measurements of these enzymes in adipose tissue. 2. In all three tissues pyruvate carboxylase activity was greatest in the rat and lowest in the rabbit. 3. Guinea pig and rabbit were very similar to each other with respect to the extramitochondrial-mitochondrial distribution of phosphoenolpyruvate carboxykinase in all three tissues. 4. NADP-malate dehydrogenase was present in all three tissues in the rat, present in kidney cortex and adipose tissue in the guinea pig and absent from all tissues examines in the rabbit.
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PMID:The activities and intracellular distribution of nicotinamide-adenine dinucleotide phosphate-malate dehydrogenase, phosphoenolpyruvate carboxykinase and pyruvate carboxylase in rat, guinea-pig and rabbit tissues. 23 92

The process of isolation and purification of malate dehydrogenase (decarboxylating) (EC 1.1.1.40) from the mycelium of the actinomycete Streptomyces aureofaciens has been worked out. The enzyme was purified 35 fold. The kinetic characters of the purified enzyme are very similar to the figures for malate dehydrogenase (decarboxylating) from other sources. Km for L-malate = 2.1 X 10(-3)M, Km for NADP = 4.6 X 10(-5)M (at pH 7.4). The reaction requires metal divalent ions, Mn2+ being more effective than Mg2+. The enzyme reaches its maximal activity at pH 8.75.
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PMID:Regulation of biosynthesis of secondary metabolites. XVII. Purification and properties of malate dehydrogenase (decarboxylating) in Streptomyces aureofaciens. 24 Jul 62

In order to obtain a quantitative estimate of the capacity of the pancreatic islets for provision of cytoplasmic acetyl-coenzyme A and for the turnover of nicotinamide adenine dinucleotide phosphate and its reduced form (NADP+/NADPH), the following enzymes were assayed in islets taken from New Zealand Obese mice: adenosine triphosphate citrate lyase (EC 4.1.3.8), malate dehydrogenase (decarboxylating) (NADP+) (EC 1.1.1.40), glutathione reductase (EC 1.6.4.2) and isocitrate dehydrogenase (NADP+) (EC 1.1.1.42). In addition, the activity of isocitrate dehydrogenase (NAD+) (EC 1.1.1.41) was determined. For comparative purposes the activities in exocrine pancreas, liver, heart muscle, kidney cortex and skeletal muscle were also determined. Specimens of pancreatic islets and the other tissues were microdissected from freeze-dried sections. In comparison with the other tissues, adenosine triphosphate citrate lyase was particularly active in the islets. The NADP+/NAPH-converting enzymes had activities, which suggested a rapid turnover of the islet NADP+/NADPH pool.
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PMID:Nicotinamide adenine dinucleotide phosphate-converting enzymes and adenosine triphosphate citrate lyase in some tissues and organs of New Zealand obese mice with special reference to the enzyme pattern of the pancreatic islets. 24 Aug 82


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