Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.1.1.37 (malate dehydrogenase)
 4,591 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell-free extracts of Rickettsia typhi were tested for activities of enzymes of the tricarboxylic acid cycle, of glutamate catabolism, and of glycolysis. The organisms were grown in the yolk sacs of chicken embryos, harvested shortly before the time of embryo death, purified by Renografin density gradient centrifugation, and ruptured in a French pressure cell. The following enzymatic activities were demonstrated: high levels of malate dehydrogenase (MDH), moderate levels of glutamate-oxaloacetate transaminase, glutamate, succinate, and isocitrate dehydrogenases, and citrate synthase, and low levels of glutamate-pyruvate transaminase. The specific activities of some of these enzymes were higher when the rickettsiae were harvested at a time of active proliferation, 3 to 4 days prior to embryo death. Rickettsial MDH was differentiated from host MDH by its migration pattern on polyacrylamide gel electrophoresis. The activities of MDH and two other dehydrogenases, demonstrable after the cells had been disrupted, were absent from purified, intact rickettsial preparations. No activity was detected for glucose-6-phosphate, 6-phosphogluconate, glyceraldehyde-3-phosphate, lactate dehydrogenases, phosphoglucose isomerase, fructoaldolase, or pyruvate kinase. Our results suggest that extracts of R. typhi that contain demonstrable enzymes involved in the catabolism of glutamate and tricarboxylic acid cycle intermediates, unlike Coxiella burnetti, lack detectable glycolytic activity.
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PMID:Enzymatic activities of cell-free extracts of Rickettsia typhi. 82 Jun 44

(1) The rate of palmitate oxidation in the 7800 C1 Morris hepatoma cells was about 60% of the activity observed in hepatocytes. The stimulatory effect of glucagon in hepatocytes was not observed in the hepatoma cells. The rate of fatty acid synthesis from [2-14C]acetate in the hepatoma cells was 1/20 of the activity in hepatocytes. The conversion of [2-14C]acetate to cholesterol was not different in the two kinds of cell. (2) Acetyl-CoA carboxylase and fatty acid synthetase were significantly decreased in the hepatoma cells. The hepatoma cells had, however, raised activities of malate dehydrogenase (decarboxylating), and glucose-6-phosphate and 6-phosphogluconate dehydrogenases. (3) The activities of the enzymes were not affected by different concentrations of glucose or palmitate in the culture medium. Insulin, dexamethasone, triiothyronine and glucagon had no effect on the enzyme activities. This is in contrast to the adaptation of the peroxisomal beta-oxidation system, which is induced by fatty acids and modified by hormones.
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PMID:Activities of enzymes of lipid metabolism in Morris hepatoma 7800 C1 cells. 256 35

A cyclic pathway of NADPH generation involving interconversion of mannitol and fructose has been proposed to occur in fungi. In Aspergillus nidulans three enzymes of this proposed mannitol cycle (hexokinase, NADP-mannitol dehydrogenase and mannitol-l-phosphate phosphatase) were shown to be localized exclusively in the cytosol. Two isoenzymes of the fourth enzyme (mannitol-l-phosphate dehydrogenase) were detected and shown to be localized respectively in the mitochondrion and the cytosol. The mitochondrial isoenzyme appeared to be present on the outer face of the inner mitochondrial membrane. No evidence was found for a coordinated change in the maximal activities of the enzymes of the proposed mannitol cycle in extracts prepared from mycelia grown on six different carbon, and three different nitrogen sources nor for any increase in these activities induced by growth on NO3-. Studies of this type in which other NADP-linked dehydrogenases were measured showed that for most carbon sources tested growth on NO3- increased the maximal activity of NADP-isocitrate dehydrogenase as well as that of glucose-6-phosphate and 6-phosphogluconate dehydrogenases but had little effect on the maximal activity of NADP-malate dehydrogenase (decarboxylating). Our studies provide no support for the operation of the mannitol cycle, or for the proposed role of this cycle in NADPH generation in A. nidulans.
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PMID:NADPH generation in Aspergillus nidulans: is the mannitol cycle involved? 314 71

Control of the activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malate dehydrogenase was investigated in intact rats and in hepatocyte cultures. 1) Adult females had 2-fold greater activities of hepatic glucose-6-phosphate- and 6-phosphogluconate dehydrogenases than adult males, but similar activities of malate dehydrogenase. Castrated males showed decreased activities of all three enzymes in comparison to age- and weight-matched intact controls. In starved animals the activities of all three enzymes decreased significantly. After refeeding with nonpurified diet the activities returned to the prestarved levels in females, but increased to clearly higher values in intact and castrated males. 2) Estrogen levels were in the same range in immature and adult male and female rats. Testosterone levels were highest in adult males, clearly lower in adult females (1/8) and immature males (1/8), still lower in immature females (1/15) and lowest in castrated males (1/40). A simple correlation of the sex differences in these hormone levels to sex differences in glucose-6-phosphate- and 6-phosphogluconate dehydrogenase activities was not apparent. 3) In serum-free, dexamethasone-supplemented 48-h cultures of hepatocytes from both male and female rats the basal activities of glucose-6-phosphate dehydrogenase were the same; they were increased 2-3 fold by insulin alone, 1.5 fold by estrogen alone and 4-5 fold by insulin plus estrogen. Apparently sex differences did not persist in 48-h cell cultures. 4) In 48-h cultures of male hepatocytes, then used as the experimental model, insulin alone increased the activity not only of glucose-6-phosphate dehydrogenase but also of 6-phosphogluconate and malate dehydrogenases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sex differences in the control of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Interaction of estrogen, testosterone and insulin in the regulation of enzyme levels in vivo and in cultured hepatocytes. 331 Oct 73

Excessive fat accumulation in the liver is a common metabolic disorder seen in humans and animals. Fatty liver was induced in the rat by feeding the animals with a sucrose rich diet containing 1% orotic acid for 2-3 weeks. In the sera from fatty liver rats there were significant changes in the level of alanine aminotransferase (+ 68.7%), malic dehydrogenase (+ 77.8%), gamma-glutamyl transpeptidase (- 53.4%) and total lipids (+ 26.6%). There were small to no changes in the levels of aspartate aminotransferase, glucose-6-phosphate dehydrogenase, lactic dehydrogenase, aldolase, malic enzyme, 6-phosphogluconic acid dehydrogenase, alkaline phosphatase and albumin. In fatty liver, significant differences were seen in the levels of glucose 6-phosphate dehydrogenase (+ 235%), malic enzyme (+ 170%), gamma-glutamyl transpeptidase (+ 113%), 6-phosphogluconate dehydrogenase (+ 63%), aspartate aminotransferase (+ 35.6%), malic dehydrogenase (+ 38%), lactic dehydrogenase (+ 37%), and alanine aminotransferase (- 23%). Comparison of the non-fatty part with the fatty part of the fatty liver showed larger changes in the non-fatty part of the liver, suggesting that during the fattening process, there is an induction of enzymes in the liver reaching a peak prior to lipid accumulation, declining thereafter during liver fattening. The increase in NADPH-generating lipogenic enzymes suggests that accumulated fat in the liver is at least partially from de-novo increased synthesis in the liver.
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PMID:Biochemical changes in liver and blood during liver fattening in rats. 377 7

Histochemical analysis for NADP-dependent dehydrogenases, succinate dehydrogenase, NADH and NADPH- tetrazoleum reductases and esterase was conducted on primary cultures of adipose tissue stromal-vascular cells. Enzyme activities were restricted to clusters of lipid laden cells (adipocytes). The number of enzyme reactive adipocytes increased with length of culture. Coverslips were partially coated with collagen to allow comparisons of cell differentiation on coated (C-glass) and uncoated glass (U-glass) surface. There were no reactions for NADH- and NADPH- tetrazoleum reductases (TR) in cells on C-glass whereas adipocytes and stromal cells on U-glass were reactive. Glucose-6-phosphate (G6PDH) and 6-phosphogluconate (6PGDH) dehydrogenase activities were markedly demonstrated in both stromal cells and adipocytes on U-glass. Malate (MDH) and isocitrate (ICDH) dehydrogenase activities were higher in adipocytes than in stromal cells on the U-glass. Stromal cells on C-glass were either devoid of these enzymes (G6PDH, MDH, 6PGDH, ICDH) or activity was restricted to a small area of the cytoplasm. There were two levels of staining intensity in (MDH, ICDH, G6PDH, 6PGDH) adipocyte clusters on C-glass. Elimination of phenazine methosulphate from the NADP-dependent dehydrogenase medias and SDH media, caused a reduction in enzyme reactive adipocytes on the C-glass. This manipulation did not reduce the number of enzyme reactive cells on U-glass. Cells on C-glass and U-glass were distinctly different in esterase stained coverslips. These studies demonstrated enzyme histochemical reactions of adipocytes and stromal cells in primary culture that were dependent on the type of extracellular matrix. Furthermore, enzyme histochemistry was shown to be useful for delineating adipocytes from stromal cells in primary cultures.
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PMID:The histochemistry of developing adipocytes in primary stromal-vascular cultures of rat adipose tissue. 642 89

In an in vitro study with rat liver, ammonium meta vanadate (NH4VO3) was found to inhibit microsomal ketamine N-demethylation, lipid peroxidation, and hydrogen peroxide formation; to have no effects on 4-methylaminoantipyrine N-demethylation and on glucuronyltransferase I activity, and to enhance glucuronyltransferase II. Mitochondrial succinate dehydrogenase and cytochrome c reductase were inhibited but cytochrome oxidase activity was enhanced by ammonium vanadate. Ammonium meta vanadate increased malate dehydrogenase activity but had no effect on glutamate, lactate, glycerophosphate, isocitrate, glucose-6-phosphate, and 6-phosphogluconate dehydrogenases.
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PMID:Action of ammonium meta vanadate on hepatic enzymes in vitro. 660 35

Biopsies from 15 human gliomas, five meningiomas, four Schwannomas, one medulloblastoma, and four normal brain areas were analyzed for 12 enzymes of energy metabolism and 12 related metabolites and cofactors. Samples, 0.01-0.25 microgram dry weight, were dissected from freeze-dried microtome sections to permit all the assays on a given specimen to be made, as far as possible, on nonnecrotic pure tumor tissue from the same region. Great diversity was found with regard to both enzyme activities and metabolite levels among individual tumors, but the following generalities can be made. Activities of hexokinase, phosphorylase, phosphofructokinase, glycerophosphate dehydrogenase, citrate synthase, and malate dehydrogenase levels were usually lower than in brain; glycogen synthase and glucose-6-phosphate dehydrogenase were usually higher; and the averages for pyruvate kinase, lactate dehydrogenase, 6-phosphogluconate dehydrogenase, and beta-hydroxyacyl coenzyme A dehydrogenase were not greatly different from brain. Levels of eight of the 12 enzymes were distinctly lower among the Schwannomas than in the other two groups. Average levels of glucose-6-phosphate, lactate, pyruvate, and uridine diphosphoglucose were more than twice those of brain; 6-phosphogluconate and citrate were about 70% higher than in brain; glucose, glycogen, glycerol-1-phosphate, and malate averages ranged from 104% to 127% of brain; and fructose-1,6-bisphosphate and glucose-1,6-bisphosphate levels were on the average 50% and 70% those of brain, respectively.
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PMID:Diversity of metabolic patterns in human brain tumors: enzymes of energy metabolism and related metabolites and cofactors. 661 61

The enzyme activity levels of alcohol, malate, isocitrate, glucose-6-phosphate and 6-phosphogluconate dehydrogenases were determined in mature maize scutella in a series of one to four doses of the long arm of chromosome 1, produced by the B-A translocation 1La. Although the Adh structural locus was varied, ADH levels did not exhibit a gene-dosage effect. The levels of G6PDH, 6PGDH and IDH were negatively correlated with the dosage of 1L. MDH was unresponsive. The esterase-8 enzyme, whose structural locus was demonstrated to be elsewhere in the genome, was also negatively correlated with 1L dosage. The portion of the B chromosome involved in the translocation was shown to have no effect on the enzyme levels. Measurements of cell size and hydrolysable DNA per mg dry weight revealed no change in the number of cells through the one, two and three dose series. The topic of enzyme alterations in aneuploids is reviewed.
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PMID:A study of enzyme activities in a dosage series of the long arm of chromosome one in maize. 1724 47

Nandrolone decanoate (ND) is an anabolic steroid, modified to enhance anabolic rather than androgenic actions. The physiological effects of ND treatment are often used in various aspects of medical practice. In this investigation we have tried to establish whether a single, high dose of ND (20 mg/kg) would cause any anabolic effects. Moreover, we have attempted to correlate the eventual effects with changes in the activity and kinetic properties of anabolic- and bioenergetic-involved enzymes in different tissues of rats, along with the rats' ECG parameters. The body and liver weights of the rats were unchanged, but heart weight had increased 10 days after ND injection. Electrocardiographic data showed a small prolongation of the QRS complex 3, 6, and 10 days after ND treatment. It was established that ND causes activation of glucose-6-phosphate and 6-phosphogluconate dehydrogenases, malic enzyme, and NADP-linked isocitrate dehydrogenase in rat hearts. Moreover, 6-phosphogluconate dehydrogenase from the hearts of ND-treated rats showed higher affinity to its substrate, in comparison with control. Activation of transketolase by ND in the liver was accompanied by inhibition of glucose-6-phosphate and 6-phosphogluconate dehydrogenases. We observed an increase of glucose 6-phosphate dehydrogenase and NAD-linked malate dehydrogenase in the muscle of ND treated rats. It may be concluded that ND in a single high dose exhibits cardiotrophic action, especially towards the increase of heart dehydrogenases activity which generates NADPH and supplies ribose phosphate for the biosynthesis of nucleotides and nucleic acids. On the other hand, ND may cause activation of ATP synthesis in muscle by enhanced malate-aspartate shuttle action.
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PMID:Effect of anabolic steroid nandrolone decanoate on the properties of certain enzymes in the heart, liver, and muscle of rats, and their effect on rats' cardiac electrophysiology. 1744 64


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