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)

To study the possible hepatotoxicity of vitamin A supplementation and its potentiation by ethanol, rats were fed diets with either normal or fivefold increased vitamin A content, both with or without ethanol. Ethanol with a normal vitamin A diet produced the expected proliferation of the smooth endoplasmic reticulum and moderate mitochondrial lesions. Vitamin A supplementation by itself produced endoplasmic reticulum proliferation, slight enlargement of mitochondria, and moderate decrease in cytochrome oxidase activity and cytochrome aa3 content. The combination of high vitamin A and ethanol resulted in much more striking lesions, with giant mitochondria containing paracrystalline inclusions and depression of oxygen consumption in state-3 respiration with five different substrates, including palmitate and palmitoyl coA. The depression of fatty acid oxidation may have contributed to the lipid accumulation. The blood levels of vitamin A were unaffected whereas liver levels of vitamin A were increased by vitamin A supplementation and decreased by ethanol. As a net result the liver vitamin A content of the high-A-ethanol groups was not greater than that of the normal-A-control group, suggesting that a metabolite of vitamin A rather than vitamin A itself may have been responsible for the potentiation of vitamin A toxicity by ethanol. Mitochondrial toxicity reflected itself also in decreased content of various cytochromes and reduced activity of enzymes, including glutamate dehydrogenase. The activity of the latter was increased in the serum. Implications of these findings for the routine treatment of alcoholics with vitamin A and the monitoring for possible signs of toxicity are discussed.
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PMID:Hepatotoxicity of vitamin A and ethanol in the rat. 627 29

This study examines the structural relationship of mitochondria and the endoplasmic reticulum in liver. Livers of rat and Japanese quail were homogenized and fractionated in media of 0.25 M-sucrose, either 5mM or 50 mM in sodium Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid], pH 7.4 (2.2 mM or 22 mM in Na respectively), designated here as low- and high-salt media. Three particulate fractions were prepared by sequential centrifugation. A nuclear pellet sedimenting at 300 g was obtained as described by Shore & Tata [(1977) J. Cell Biol. 72, 714-725], and from the resulting supernatant thereof a low-speed pellet (1100-1500 g) and a high-speed pellet (8000-10 000 g) were prepared. In the low-salt medium the yields of mitochondrial matrix enzymes (citrate synthase, glutamate dehydrogenase, ornithine carbamoyltransferase) and their specific activities in the low-speed pellet were over twice those in the high-speed pellet. In the high-salt medium the yield of matrix enzymes was 4-5 times, and the specific activities were up to 3 times, higher in the low-speed pellet than in the high-speed pellet. Oxygen uptake and respiratory control ratio were also much higher in the low-speed pellets in both media. Some 50-65% of the microsomal marker enzyme glucose 6-phosphatase was in the supernatant from the high-speed pellet, and the rest sedimented with the mitochondria. Repeated washing with the high-salt medium removes only a limited amount of reticulum. Washing with salt-free sucrose removes most of the reticulum, but a fraction remains strongly bound to mitochondria. Homogenates from quail and rat liver were fractioned isopycnically on Percoll gradients in either 0.25 M-sucrose or 0.25 M-sucrose/50 mM-sodium Hepes. Up to five particulate bands were separated and assayed. Mitochondria were present in two to three bands and were associated with endoplasmic reticulum. As seen in the phase-contrast microscope the mitochondria prepared in the low-salt medium consist of separate organelles. In the high-salt medium the mitochondria appear as chains of from three to ten organelles not touching each other. On addition of univalent ions at concentrations above 20 mM, the mitochondria aggregate into chains, and at higher ionic strength larger multidimensional aggregates are formed. The dispersion and aggregation of mitochondria are reversible. Negatively stained electron micrographs reveal a branched mitochondrial structure, with mitochondria held together by strands of reticulum.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Mitochondrial-reticular cytostructure in liver cells. 635 78

1. The maximum activity of hexokinase in lymphocytes is similar to that of 6-phosphofructokinase, but considerably greater than that of phosphorylase, suggesting that glucose rather than glycogen is the major carbohydrate fuel for these cells. Starvation increased slightly the activities of some of the glycolytic enzymes. A local immunological challenge in vivo (a graft-versus-host reaction) increased the activities of hexokinase, 6-phosphofructokinase, pyruvate kinase and lactate dehydrogenase, confirming the importance of the glycolytic pathway in cell division. 2. The activities of the ketone-body-utilizing enzymes were lower than those of hexokinase or 6-phosphofructokinase, unlike in muscle and brain, and were not affected by starvation. It is suggested that the ketone bodies will not provide a quantitatively important alternative fuel to glucose in lymphocytes. 3. Of the enzymes of the tricarboxylic acid cycle whose activities were measured, that of oxoglutarate dehydrogenase was the lowest, yet its activity (about 4.0mumol/min per g dry wt. at 37 degrees C) was considerably greater than the flux through the cycle (0.5mumol/min per g calculated from oxygen consumption by incubated lymphocytes). The activity was decreased by starvation, but that of citrate synthase was increased by the local immunological challenge in vivo. It is suggested that the rate of the cycle would increase towards the capacity indicated by oxoglutarate dehydrogenase in proliferating lymphocytes. 4. Enzymes possibly involved in the pathway of glutamine oxidation were measured in lymphocytes, which suggests that an aminotransferase reaction(s) (probably aspartate aminotransferase) is important in the conversion of glutamate into oxoglutarate rather than glutamate dehydrogenase, and that the maximum activity of glutaminase is markedly in excess of the rate of glutamine utilization by incubated lymphocytes. The activity of glutaminase is increased by both starvation and the local immunological challenge in vivo. This last finding suggests that metabolism of glutamine via glutaminase is important in proliferating lymphocytes.
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PMID:Maximum activities of some enzymes of glycolysis, the tricarboxylic acid cycle and ketone-body and glutamine utilization pathways in lymphocytes of the rat. 716 29

The chain oxidation of glyceraldehyde-3-phosphate dehydrogenase.NADH by perhydroxyl radicals and propagated by molecular oxygen was studied by the xanthine-xanthine oxidase system, 60Co gamma-ray, and pulse radiolysis. The chain length, amount of NADH oxidized per HO2 generated, increases with increasing acidity of the medium and reaches a value of 73 at pH 5.0. The rate constant for the oxidation of the glyceraldehyde-3-phosphate dehydrogenase.NADH complex by HO2 was estimated to be 2 X 10(7) M-1 S-1 at ambient temperatures (23-24 degrees C). Rate studies as a function of pH indicate that O2- is unreactive toward the glyceraldehyde-3-phosphate dehydrogenase.NADH complex. Other dehydrogenases (malate dehydrogenase, glutamate dehydrogenase, and isocitric dehydrogenase) studied showed no catalytic activity in the oxidation of NADH by HO2/O2-.
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PMID:Glyceraldehyde-3-phosphate dehydrogenase-catalyzed chain oxidation of reduced nicotinamide adenine dinucleotide by perhydroxyl radicals. 718 97

The effects of short- and long-term ethanol administration on the hepatic content of free proline and on the activity of hepatic enzymes that catalyze the formation and degradation of proline were determined in the rat. The short-term oral administration of ethanol in a dose of 5.5 gm/kg body weight resulted in no changes in hepatic free proline content or in hepatic proline oxidase activity. By contrast, the feeding of ethanol for a period of 1 month resulted in an increase in the total hepatic content of free proline. The hepatic activity of proline exidase was also increased by long-term ethanol feeding while the activities of arginase, ornithine aminotransferase, delta 1-pyrroline-5-carboxylate reductase, delta 1-pyrroline-5-dehydrogenase, and glutamate dehydrogenase remained unchanged. The increase in the hepatic pool of free proline in association with an increase in proline oxidase activity suggests that long-term ethanol administration results in an increased turnover of proline in the liver, in which the increase in synthesis is greater than the increase in degradation. An effect of long-term ethanol feeding in increasing proline degradation mya be a cause for the increased oxygen consumption and urea production found in the liver after long-term ethanol ingestion.
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PMID:Effect of ethanol on hepatic proline-metabolizing enzymes in the rat. 729 45

Alveolar and peritoneal macrophages differ in their energy metabolism. Alveolar macrophages are mainly aerobic whereas peritoneal macrophages are mainly anaerobic in their energy generation. We investigated the question of whether these differences in metabolism are preprogrammed in subsets of macrophage precursors in the bone marrow, or develop in proliferating cells as a consequence of exposure to different tissue environments. The progeny of single mouse macrophage progenitor cells were grown in vitro for 4 days; the resultant colonies were divided into two roughly equal populations, which were cultured in either a high or low oxygen environment corresponding to that of the alveoli or tissues. Following 4 days incubation at 5% or 20% O2, the activities of the two glycolytic enzymes lactate dehydrogenase (LDH) and pyruvate kinase (PK) were two- to threefold higher in the half of the colonies grown in the low O2 environment, whereas the activity of the oxidative phosphorylative enzyme glutamate dehydrogenase (GDH) was two- to threefold higher in the half colony grown in the aerobic environment. Re-exposure of the cells from the low O2 environment to high O2 conditions for an additional 4 days caused a rise in the GDH activity and a decrease in the LDH and PK. The recovery of the GDH activity after the re-exposure was time dependent. Our results support the theory that macrophages arising from a single progenitor cell can develop different metabolic features depending on the O2 environment in which they mature. A single precursor cell can give rise to mature cells with metabolic characteristic of either alveolar or tissue macrophages.
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PMID:The progeny of a single progenitor cell can develop characteristics of either a tissue or an alveolar macrophage. 744 18

Porphyrin-induced photodamage has been studied on small organic molecules, biomolecules, mitochondria and red cells. Water soluble components (e.g. tryptophan and glutamate dehydrogenase) are more easily destroyed by uroporphyrin than by protoporphyrin. On the other hand, lipophilic components (e.g. succinate dehydrogenase, mitochondria and red cell membranes) are more severely damaged by protoporphyrin. The results may be of importance to explain the different skin lesions in erythropoietic protoporphyria and in porphyria cutanea tarda. The photodamage is enhanced by D2O and reduced by azide. Reagents known to increase or decrease the yields of superoxide, peroxide or hydroxyl radicals have no effect on the photodamage. The results suggest that singlet oxygen is the most important reactive oxygen species.
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PMID:Porphyrin-induced photodamage at the cellular and the subcellular level as related to the solubility of the porphyrin. 747 96

A strategy for the multifunctionalization of the FIA biosensor was developed. The described multifunctional FIA system offers a fast and simple method for the simultaneous determination of ammonia, creatinine, and urea. The hydrolysis of creatinine by creatinine deiminase (CRDI) or of urea by urease forms ammonia, which is amperometrically detected by an oxygen electrode, based on an enzyme conversion system, glutamate dehydrogenase (GLDH)/glutamate oxidase (GLOD). The split of the stream into three after sample injection and confluence before the GLDH reactor resulted in a three-channel system, into which were set three parallel columns, respectively, filled with immobilized CRDI, urease, and CPG. A triple-peak recording was obtained by putting two delay coils at the channels involving CRDI and urease. Thus the interfering of the endogenous ammonia on the creatinine and urea assay is simultaneously compensated. Furthermore, the problem of great difference in concentration between urea and the other two components is resolved by taking advantage of the differentiated dilution effect for each channel caused from the split-stream, flow-injection system. Linear calibration ranges for ammonia, creatinine, and urea were 0.1-5, 0.2-10, and 2-40 mM, respectively. One run was finished within 5 minutes, and the system was reproducibility good (3 to 5%). The results of the urine assay obtained by the present method will be described in the near future.
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PMID:A multifunctional flow-injection biosensor for the simultaneous determination of ammonia, creatinine, and urea. 778 57

Little is known about the kinetics of most serum enzymes during the first hours of life, and even less about the effect on such enzyme activities of perinatal hypoxia-ischaemia. It was the aim of the present study to evaluate the serum kinetics of seven differently located cell enzymes in healthy and asphyxiated newborns during the 1st week of life. The serum activities of cytoplasmic and mitochondrial [aspartate aminotransferase (ASAT), creatine kinase (CK), glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH), and hydroxybutyrate dehydrogenase (HBDH)] and membrane-bound (gamma-glutamyl-transferase and leucine arylaminidase) enzymes were prospectively measured in full-term asphyxiated (n = 49) and healthy (n = 87) newborns during the first 144 h of life. The blood samples were taken serially at five fixed times: 0 (cord), 12, 24, 72, and 144 h postpartum. The asphyxiated newborns had significantly increased serum activities of ASAT, LDH, and HBDH up to 72 h postpartum, whereas healthy newborns showed higher CK and GLDH activities. Only the activities of ASAT, LDH, and HBDH seemed to depend on the oxygen supply of the fetus or newborn. If other causes of increased serum enzyme activities, e.g. liver diseases, haemolytic disorders, tumours, or inborn errors of metabolism, are excluded, elevated serum activities of ASAT, LDH, and HBDH should draw one's attention to a perinatal hypoxic-ischaemic insult of the newborn.
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PMID:Serum enzyme activities in full-term asphyxiated and healthy newborns: enzyme kinetics during the first 144 hours of life. 791 42

Leucine dehydrogenase/L-amino acid oxidase was proposed as an enzymatic conversion system for ammonia and its application to amperometric assay of creatinine was investigated. Ammonia formed by creatinine deiminase catalyzed hydrolysis of creatinine was converted to L-leucine by leucine dehydrogenase, and the oxidation of L-leucine by L-amino acid oxidase was detected with an oxygen electrode. Two approaches were proposed to overcome the problem of endogenous ammonia and L-amino acids. The first was using glutamate dehydrogenase prereactor to remove endogenous ammonia; endogenous L-amino acids were corrected by a separate run. In the second approach, endogenous ammonia and L-amino acids were simultaneously compensated with a two-channel system. It resulted in double peak recording that the flow was split and rejoined between the two ends of creatinine deiminase reactor and a delay coil and a reference column were properly set at one of the two-channels. One gave the sum response of all responsible compounds, the other that of endogenous interferences except creatinine. Both approaches were applied to creatinine assay in urine and the results showed a good agreement with those obtained from the Jaffe method.
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PMID:Amperometric flow-injection analysis of creatinine based on immobilized creatinine deiminase, leucine dehydrogenase and L-amino acid oxidase. 791 82


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