Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The metabolic activity of Pneumocystis carinii cysts was studied histochemically by a tetrazolium dye technique to assess substrate-specific dehydrogenase activity. Lactate dehydrogenase, succinate dehydrogenase, and glutamate dehydrogenase produced moderate-to-strong reactions in the cysts, whereas glucose-6-phosphate dehydrogenase had little if any reactivity. These results suggest that pneumocystis cysts have some of the enzymes necessary for glycolysis, Krebs cycle activity, and intermediary protein metabolism. These studies provide a method of directly assessing metabolic pathways in P. carinii which circumvents the uncertainties of specificity inherent in previous investigations with partially purified suspensions.
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PMID:Histoenzymological study of selected dehydrogenase enzymes in Pneumocystis carinii. 354 38

The activities of certain key enzymes have been measured in the ventral medial and ventral lateral areas of the hypothalamus, which are implicated in feeding behaviour, and compared with enzyme activities in the cortex and brainstem. The enzymes measured are concerned with glucose metabolism [hexokinase (EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49)], ketone body metabolism [3-hydroxybutyrate dehydrogenase (EC 1.1.1.30)], fatty acid utilisation [carnitine palmitoyl transferase (EC 2.3.1.7)], citric acid cycle activity [pyruvate dehydrogenase (EC 1.2.4.2) and citrate synthase (EC 4.1.3.7)] and neurotransmitter synthesis [glutamate dehydrogenase (EC 1.4.1.3)].
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PMID:Enzyme activities in regions of the hypothalamus. 380 3

In porcine areolar placental epithelia, the following enzymes were demonstrated by histochemical methods after 30, 58, 80, 100, and 110 d of pregnancy, respectively: beta-N-acetyl-hexosaminidase, beta-galactosidase, beta-glucuronidase, alpha-mannosidase, acid phosphatase, alkaline phosphatase, nonspecific esterases, cytochrome oxidase, 5-nucleotidase, leucine aminopeptidase, adenosine triphosphatase, diaphorases (NADH, NADPH), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase (NAD, NADP), beta-hydroxybutyrate dehydrogenase, glycero-3-phosphate dehydrogenase, NAD-glycero-3-phosphate dehydrogenase, glutamate dehydrogenase (NAD, NADP), lactate dehydrogenase. The results show that the enzyme activities remained almost unchanged during the period of investigation. Of the dehydrogenases, the diaphorases as well as succinate and lactate dehydrogenase demonstrated generally an intensive activity within the epithelia. The activity of the other dehydrogenases was only low. The activity of unspecific esterase was very intensive within the uterine epithelia but remarkably low within chorionic epithelia. Contrarily, the reaction of adenosine triphosphatase was more intensive within chorionic than uterine epithelia. All investigated glucosidases reacted distinctly positive within chorionic epithelia, but only beta-N-acetyl-hexosaminidase and beta-galactosidase in uterine epithelia. The high activity of acid phosphatase, especially within the chorionic epithelium, seems to be connected with uteroferrin, an iron-binding protein. The histochemical results are discussed in context with the function of the areolae in histiotrophic nutrition and iron transport.
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PMID:[Enzyme-histochemical studies of the pig placenta. II. Histotopics of enzymes in the areolar placenta epithelium]. 392 41

Primary roots of soybean [Glycine max (L.), cv Harosoy 63] seedlings were inoculated with zoospores from either race 1 (incompatible, host resistant) or race 3 (compatible, host susceptible) of Phytophthora megasperma f. sp. glycinea (Pmg) and the activities of phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), isoflavone synthase, and dihydroxypterocarpan 6a-hydroxylase related to phytoalexin (glyceollin) biosynthesis, and of glucose-6-phosphate dehydrogenase (Glc-6-PDH) and glutamate dehydrogenase (Glu-DH) were determined at various times after inoculation. About 2-4 h after inoculation with race 1, the activities of PAL, CHS, and pterocarpan 6a-hydroxylase were higher than after inoculation with race 3 and increased considerably thereafter. In contrast, activities of these enzymes in the compatible interaction were equal to or only slightly higher than in the controls over the entire infection period investigated (2-8 h). Isoflavone synthase did not increase until 7 h after inoculation with race 1. There were no significant differences in activities for Glc-6-PDH and Glu-DH between inoculated roots and controls. The results show that infection of soybean roots with zoospores of Pmg race 1 causes a race:cultivar-specific early induction of enzymes involved in glyceollin synthesis, whereas such an induction does not occur with zoospores of race 3. These findings are in agreement with the race:cultivar-specific accumulation of glyceollin in soybean roots reported previously [M. G. Hahn, A. Bonhoff, and H. Grisebach (1985) Plant Physiol. 77, 591-601].
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PMID:Race:cultivar-specific induction of enzymes related to phytoalexin biosynthesis in soybean roots following infection with Phytophthora megasperma f. sp. glycinea. 396 19

Coenzymic activities of the following NADP derivatives were investigated: 2'-O-(2-carboxyethyl)phosphono-NAD (I), N6-(2-carboxyethyl)-NADP (II), 2'-O-(2-carboxyethyl)phosphono-N6-(2-carboxyethyl)-NAD (III), 2'-O-[N-(2-aminoethyl)carbamoylethyl]phosphono-NAD (IV), N6-[N-(2-aminoethyl)carbamoylethyl]-NADP (Va), 2',3'-cyclic NADP, and 3'-NADP. Derivatives I and IV show the effects of modification at the 2'-phosphate group, and derivatives II and Va show those at the 6-amino group of NADP. As for enzymes, alcohol, isocitrate, 6-phosphogluconate, glucose, glucose-6-phosphate, and glutamate dehydrogenases were used. These enzymes were grouped on the basis of the ratio of the activities for NAD and NADP into NADP-specific enzymes (ratio less than 0.01), NAD(P)-specific enzymes (0.01 less than ratio less than 100), and NAD-specific enzymes (ratio greater than 100). For NADP-specific enzymes, modifications at the 2'-phosphate group of NADP caused great loss of cofactor activity. The relative cofactor activities (NADP = 100%) of derivatives I and IV for these enzymes were 0.5-20 and 0.01-0.5%, respectively. On the other hand, NAD(P)-specific enzymes showed several types of responses to the NADP derivatives. The relative cofactor activities of I and IV for Leuconostoc mesenteroides and Bacillus stearothermophilus glucose-6-phosphate dehydrogenases and beef liver glutamate dehydrogenase were 60-200%; whereas, for B. megaterium glucose dehydrogenase and L. mesenteroides alcohol dehydrogenase, the values were 0.8-8%. For NAD-specific enzymes, these values were 20-50%. The relative cofactor activities of 2',3'-cyclic NADP and 3'-NADP were very low (less than 0.2%) except for beef liver glutamate dehydrogenase, B. stearothermophilus glucose-6-phosphate dehydrogenase, and horse liver alcohol dehydrogenase. Kinetic studies showed that the losses of the cofactor activity of NADP by these modifications were mainly due to the increase of the Km value. The mechanisms of coenzyme specificity of dehydrogenases are discussed. Unlike the 2'-phosphate group, the 6-amino group is common to NAD and NADP, and the effects of modification at the 6-amino group were independent of the coenzyme specificity of enzymes used for the assay. Derivatives II and Va had high relative cofactor activities (65-130%) for most of the enzymes except for isocitrate and glucose dehydrogenases (less than 1%) and L. mesenteroides alcohol dehydrogenase (20-60%). The cofactor activity of derivative III was generally lower than those of I and II.
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PMID:Coenzymic activity of NADP derivatives alkylated at 2'-phosphate and 6-amino groups. 397 81

The N-1 position of the adenine ring of NADP was selectively alkylated by the reaction of 2',3'-cyclic NADP with 3-propiolactone to yield 2',3'-cyclic 1-(2-carboxyethyl)-NADP (I). Derivative I was converted to a mixture of the isomers of N6-(2-carboxyethyl)-NADP with their phosphate groups at the 2' or 3' position (IIa and IIb) by chemical reduction, alkaline rearrangement and chemical reoxidation. Carbodiimide coupling of the mixture of IIa and IIb to alpha, omega-diaminopoly(ethylene glycol) gave the 2', 3'-cyclic derivative of poly(ethylene glycol)-bound NADP (III), which was enzymically hydrolyzed to yield poly(ethylene glycol)-bound NADP (PEG-NADP). PEG-NADP has good cofactor activity (16-100% of that of NADP) for NADP-specific and NAD(P)-specific dehydrogenases except isocitrate and glucose dehydrogenases. For NAD-specific enzymes, PEG-NADP has higher cofactor activity than NADP: for horse liver alcohol dehydrogenase, the cofactor activity of PEG-NADP is 40 times that of NADP and 14% of that of NAD. Kinetic studies show that for most of enzymes tested, Km values for PEG-NADP are larger than those for NADP and V values for PEG-NADP are similar to those for NADP. PEG-NADP proved to be applicable in a continuous enzyme reactor, in which reactions of glutamate dehydrogenase and glucose-6-phosphate dehydrogenase were coupled by the recycling of PEG-NADP.
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PMID:Synthesis of poly(ethylene glycol)-bound NADP by selective modification at the 6-amino group of NADP. 402 32

Fat-cells were prepared from rat and guinea-pig epididymal adipose tissue and compared on the basis of the intracellular distributions and activities of enzymes and with respect to their utilization of various U-(14)C-labelled substrates for lipogenesis. 1. Compared with the rat, guinea-pig extramitochondrial enzyme activities differed in that aconitate hydratase, alanine aminotransferase, ATP-citrate lyase, lactate dehydrogenase, NAD-malate dehydrogenase, NADP-malate dehydrogenase and phosphoenolpyruvate carboxykinase activities were appreciably lower, whereas aspartate aminotransferase, glucose 6-phosphate dehydrogenase, NADP-isocitrate dehydrogenase and 6-phosphogluconate dehydrogenase activities were appreciably higher. Mitochondrial activities of citrate synthase, NADP-isocitrate dehydrogenase and pyruvate carboxylase were appreciably lower, whereas mitochondrial activities of aspartate aminotransferase, glutamate dehydrogenase, NAD-malate dehydrogenase and phosphoenolpyruvate carboxykinase were higher in the guinea pig compared with the rat. 2. In general guinea-pig fat-cells incorporated acetate and lactate into fatty acids more readily than rat fat-cells, whereas rat fat-cells incorporated glucose and pyruvate more readily than guinea-pig fat-cells. 3. Acetate stimulated the incorporation of glucose into fatty acids in rat fat-cells, but had no appreciable effect upon this process in guinea-pig fat-cells. Acetate greatly decreased the incorporation of lactate into fatty acids in cells from both species. 4. Lactate/pyruvate ratios produced by incubation of guinea-pig cells with glucose+insulin were very low compared with those found with rat cells under the same conditions. 5. With glucose (+insulin) or with glucose+acetate (+insulin) as substrates guinea-pig cells produced enough NADPH by the hexose monophosphate pathway to satisfy the NADPH requirements of lipogenesis. In rat fat-cells under the same conditions, hexose monophosphate-pathway NADPH provision was not sufficient to meet the requirements of lipogenesis. 6. These results are discussed, particularly in relationship to the disposition of cytosolic reducing equivalents in the cells.
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PMID:Lipogenesis in rat and guinea-pig isolated epididymal fat-cells. 415 67

Octanoic acid inhibits, in vitro, the bacterial enzymes glucose-6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase, fumarase, lactate dehydrogenase, and the malic enzyme of Arthrobacter crystallopoietes. The free fatty acid appears to act as an inhibitor of lipogenesis, although it does not affect the rate of gluconeogenesis. To demonstrate that this inhibition may be of physiological significance in vivo, those enzymes not involved in lipogenesis, such as fructose-1, 6-diphosphatase, phosphoglucomutase, phosphohexoisomerase, aconitase, nicotinamide adenine dinucleotide phosphate (NADP) isocitrate dehydrogenase, NADP glutamate dehydrogenase, malate dehydrogenase, and isocitrate lyase, were assayed and found not to be inhibited by the free fatty acid.
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PMID:Selective inhibition of bacterial enzymes by free fatty acids. 430 71

1. Lineweaver-Burk plots for glutamate dehydrogenase, glucose 6-phosphate dehydrogenase and several other enzymes show one or more abrupt transitions between apparently linear sections. These transitions correspond to abrupt increases in the apparent K(m) and V(max.) with increasing concentration of the varied substrate. 2. The generalized reciprocal initial-rate equation for a multi-site enzyme requires several restrictions to be put on it in order to generate such plots. These mathematical conditions are explored. 3. It is shown that the effective omission of a term in the denominator of the reciprocal initial-rate equation represents a minimal requirement for generation of abrupt transitions. This corresponds in physical terms to negative co-operativity followed by positive co-operativity affecting the catalytic rate constant for the reaction. 4. Previous models for glutamate dehydrogenase cannot adequately account for the results. On the other hand, the model based on both negative and positive co-operativity gives a good fit to the experimental points. 5. The conclusions are discussed in relation to current knowledge of the structure and mechanism of glutamate dehydrogenase.
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PMID:The significance of abrupt transitions in Lineweaver-Burk plots with particular reference to glutamate dehydrogenase. Negative and positive co-operativity in catalytic rate constants. 435 66

1. A method is described for extracting separately mitochondrial and extramitochondrial enzymes from fat-cells prepared by collagenase digestion from rat epididymal fat-pads. The following distribution of enzymes has been observed (with the total activities of the enzymes as units/mg of fat-cell DNA at 25 degrees C given in parenthesis). Exclusively mitochondrial enzymes: glutamate dehydrogenase (1.8), NAD-isocitrate dehydrogenase (0.5), citrate synthase (5.2), pyruvate carboxylase (3.0); exclusively extramitochondrial enzymes: glucose 6-phosphate dehydrogenase (5.8), 6-phosphogluconate dehydrogenase (5.2), NADP-malate dehydrogenase (11.0), ATP-citrate lyase (5.1); enzymes present in both mitochondrial and extramitochondrial compartments: NADP-isocitrate dehydrogenase (3.7), NAD-malate dehydrogenase (330), aconitate hydratase (1.1), carnitine acetyltransferase (0.4), acetyl-CoA synthetase (1.0), aspartate aminotransferase (1.7), alanine aminotransferase (6.1). The mean DNA content of eight preparations of fat-cells was 109mug/g dry weight of cells. 2. Mitochondria showing respiratory control ratios of 3-6 with pyruvate, about 3 with succinate and P/O ratios of approaching 3 and 2 respectively have been isolated from fat-cells. From studies of rates of oxygen uptake and of swelling in iso-osmotic solutions of ammonium salts, it is concluded that fat-cell mitochondria are permeable to the monocarboxylic acids, pyruvate and acetate; that in the presence of phosphate they are permeable to malate and succinate and to a lesser extent oxaloacetate but not fumarate; and that in the presence of both malate and phosphate they are permeable to citrate, isocitrate and 2-oxoglutarate. In addition, isolated fat-cell mitochondria have been found to oxidize acetyl l-carnitine and, slowly, l-glycerol 3-phosphate. 3. It is concluded that the major means of transport of acetyl units into the cytoplasm for fatty acid synthesis is as citrate. Extensive transport as glutamate, 2-oxoglutarate and isocitrate, as acetate and as acetyl l-carnitine appears to be ruled out by the low activities of mitochondrial aconitate hydratase, mitochondrial acetyl-CoA hydrolyase and carnitine acetyltransferase respectively. Pathways whereby oxaloacetate generated in the cytoplasm during fatty acid synthesis by ATP-citrate lyase may be returned to mitochondria for further citrate synthesis are discussed. 4. It is also concluded that fat-cells contain pathways that will allow the excess of reducing power formed in the cytoplasm when adipose tissue is incubated in glucose and insulin to be transferred to mitochondria as l-glycerol 3-phosphate or malate. When adipose tissue is incubated in pyruvate alone, reducing power for fatty acid, l-glycerol 3-phosphate and lactate formation may be transferred to the cytoplasm as citrate and malate.
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PMID:The intracellular localization of enzymes in white-adipose-tissue fat-cells and permeability properties of fat-cell mitochondria. Transfer of acetyl units and reducing power between mitochondria and cytoplasm. 439 82


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