Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.4.1.2 (glutamate dehydrogenase)
 4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Crocodilians such as caimans and alligators are uricotelic and ammoniotelic animals. They are carnivorous but they excrete ammonium ions in an alkaline urine. The metabolic organization of the kidney of the Mississippi alligator was studied by measuring the renal metabolite profile, the activities of enzymes, and the behavior of kidney tubules in vitro. The liver and tail muscle were also studied. Both awake and anesthetized animals were in a state of low plasma bicarbonate and low blood pH with high plasma lactate concentration. This did not prevent the excretion of an alkaline urine (pH 7.76). alpha-Ketoglutarate was low in all three tissues and lactate was high. Glutamate concentration and glutamate dehydrogenase activity were highest in the kidney with a low equilibrium constant for alanine aminotransferase (KGPT). Glutaminase I was found only in the kidney. It could not be detected in liver or muscle. Glutamine synthetase was found only in the liver. Phosphoenolpyruvate carboxykinase (PEPCK) was present in both liver and kidney. Alanine aminotransferase and malic enzyme showed high activity in the kidney but were inconspicuous in liver and muscle. Malate dehydrogenase and lactate dehydrogenase were present in all three tissues. Renal tubules incubated with glutamine and alanine were ammoniagenic and gluconeogenic. Lactate was gluconeogenic. Enzyme activities were measured at both 30 and 37 degrees C. The studies on renal tubules were also performed at these two temperatures. Temperature had little effect on the data including acid-base values in the blood. Our findings demonstrate that the kidney of the alligator is perfectly equipped for various metabolic functions and especially for ammoniagenesis and gluconeogenesis.
 ...
PMID:Metabolic machinery of the alligator kidney. 649 95

Glutamate dehydrogenase (L-glutamate:NAD+ oxidoreductase (deaminating); EC 1.4.1.2) has been purified from Peptostreptococcus asaccharolyticus in a single step using dye-ligand chromatography. The enzyme (GDH) was present in high yields and was stabilized in crude extracts. A subunit molecular weight of 49000 +/- 500 was determined by SDS polyacrylamide gel electrophoresis and six bands were obtained after cross-linking the subunits with dimethyl suberimidate. This bacterial GDH was predominantly NAD+-linked, but was able to utilize both NADP+ and NADPH at 4% of the rates with NAD+ and NADH, respectively. An investigation of the amino acid specificity revealed some similarities with GDH from mammalian sources and some clear differences. The values of apparent Km for the substrates ammonia, 2-oxoglutarate, NADH, NAD+ and glutamate were 18.4, 0.82, 0.066, 0.031 and 6 mM, respectively. The P. asaccharolyticus GDH was not regulated by purine nucleotides, but was subject to strong inhibition with increasing ionic strength.
 ...
PMID:Characterization of Peptostreptococcus asaccharolyticus glutamate dehydrogenase purified by dye-ligand chromatography. 650 34

The NADP-dependent glutamate dehydrogenase (EC 1.4.1.4.) elaborated by the methylotrophic bacterium Pseudomonas sp. strain AM1 when growing on succinate and ammonium chloride was studied. The enzyme, which has a pH optimum of 9.0, was purified 140-fold and shown to have Km values of 20.2 mM, 0.76 mM, 0.033 mM, and 31.6 mM for ammonia, alpha-ketoglutarate, NADPH, and glutamate, respectively. The native molecular weight was determined by polyacrylamide gel electrophoresis to be 190,000, and electrophoresis under denaturing conditions in the presence of sodium dodecyl sulfate revealed a minimum molecular weight of 50,000. The enzyme was highly specific; NADH was unable to replace NADPH in the reaction, various alpha-keto acids could not replace alpha-ketoglutarate, and neither methylamine nor hydroxylamine could substitute for ammonia. Glutamate dehydrogenase was synthesized by the bacteria only when ammonia was its nitrogen source and was repressed if methylamine or nitrate were provided as sources of nitrogen instead of ammonia.
 ...
PMID:NADP-dependent glutamate dehydrogenase from a facultative methylotroph, Pseudomonas sp. strain AM1. 669 48

To provide further insight into the relationship between glutamate transport and metabolism in rat kidney mitochondria, the effect of pH on [U-14C]-glutamate efflux from [U-14C]glutamate-loaded mitochondria was tested. Glutamate efflux, measured in rotenone-inhibited energized mitochondria at 28 degrees C, was first order with respect to matrix glutamate. Glutamate efflux was tested at different medium pH values ranging from 6.4 to 7.9. Efflux was fastest at pH 7.9 with a rate constant of 0.988 min-1 and decreased progressively at lower pH values such that the rate constant at pH 6.4 was 0.359 min-1. A highly significant correlation between pH and the rate constant of glutamate efflux was observed. When medium pH was held constant at 7.0, matrix pH (range pH 7.2-8.4) did not affect the rate of glutamate efflux. The reduction in glutamate efflux at low pH provides an explanation for the increased concentration of glutamate observed in the mitochondrial matrix space of isolated rat kidney mitochondria incubated at acid medium pH. The elevated glutamate concentration in turn contributes to the accelerated oxidative deamination of glutamate by glutamate dehydrogenase at acid pH. Moreover, these findings suggest that the reduction in renal cortex glutamate levels observed in acute acidosis in vivo may be explained by a decreased rate of glutamate transport from mitochondria to cytosol coupled with an augmented rate of glutamate oxidation in the matrix.
 ...
PMID:Effect of pH on glutamate efflux from rat kidney mitochondria. 670 60

Pyrene maleimide is shown to be a 'half of the sites' reagent for glutamate dehydrogenase and for glyceraldehyde-3-phosphate dehydrogenase. The modified residues are identified as cysteine-115 for glutamate dehydrogenase and cysteine-149 for glyceraldehyde-3-phosphate dehydrogenase. The two enzymes react differently with pyrene maleimide. Whereas the hydrophobic environment of cysteine-115 directs the modification of glutamate dehydrogenase, the high reactivity of cysteine-149 determines the specific modification of glyceraldehyde-3-phosphate dehydrogenase. Glutamate dehydrogenase activity is unaltered by the modification: glyceraldehyde-3-phosphate dehydrogenase activity in inhibited.
 ...
PMID:Specific modification of a single cysteine residue in both bovine liver glutamate dehydrogenase and yeast glyceraldehyde-3-phosphate dehydrogenase. Difference in the mode of modification by pyrene maleimide. 675 39

Serum glutamate dehydrogenase concentration was assessed as a marker of the degree of hepatocyte necrosis found at liver biopsy in 95 patients suspected of having alcoholic liver disease. Although the serum concentration was raised in 54 patients, no relation between it and the severity of hepatocyte necrosis could be established. Glutamate dehydrogenase was therefore not confirmed to be a useful indicator of hepatocyte necrosis in patients with chronic alcoholism.
 ...
PMID:Serum glutamate dehydrogenase as a marker of hepatocyte necrosis in alcoholic liver disease. 679 35

Experiments performed in polyethylene glycol and with a divalent crosslinker indicate that both mitochondrial malate dehydrogenase and aspartate aminotransferase can form hetero enzyme--enzyme complexes with either glutamate dehydrogenase or citrate synthase. In general, these as previous results indicate that complexes with the aminotransferase are favored over those with malate dehydrogenase and complexes with glutamate dehydrogenase are favored over those with citrate synthase. When the levels of enzymes are low, the only detectable complex is between the aminotransferase and glutamate dehydrogenase. Under these conditions, palmitoyl-CoA is required for complexes between the other three enzyme pairs, however, palmitoyl-CoA also enhances interactions between glutamate dehydrogenase and the aminotransferase. DPNH disrupts complexes with malate dehydrogenase and has little effect on those with the aminotransferase, while oxalacetate disrupts complexes with citrate synthase but has little effect on those with glutamate dehydrogenase. The citrate synthase-aminotransferase complex was favored in the presence of DPNH plus malate, which disrupt the other three enzyme-enzyme complexes. Glutamate dehydrogenase has a higher affinity and capacity than citrate synthase for palmitoyl-CoA. Consequently, lower levels of palmitoyl-CoA are required to enhance interactions with glutamate dehydrogenase. Furthermore, glutamate dehydrogenase can compete with citrate synthase for palmitoyl-CoA and thus can prevent palmitoyl-CoA from enhancing interactions between citrate synthase and either malate dehydrogenase or the aminotransferase.
 ...
PMID:Complexes between mitochondrial enzymes and either citrate synthase or glutamate dehydrogenase. 682 31

beta-Oxidation of polyunsaturated fatty acids was studied with isolated rat liver mitochondria in state 3 or uncoupled conditions. 1. Incubation of mitochondria with docosahexaenoyl-, linolenoyl- or gamma-linolenoylcarnitine resulted in an increase of the absorbance at 340 minus 385 nm. This increased absorbance was due to an accumulation of beta-oxidation intermediates of the polyunsaturated fatty acids, and not to the reduction of nicotinamide nucleotides. 2. Experiments carried out with soluble fractions of liver mitochondria incubated with docosahexaenoyl-CoA and gamma-linolenoyl-CoA indicated that this ultraviolet light-absorption was at least partly caused by acyl-CoA esters having a 2,4(,7)-di(tri)enoyl-CoA structure. 3. The addition of glutamate to mitochondria oxidizing gamma-linolenoylcarnitine decreased the absorbance at 340 minus 385 nm, and simultaneously stimulated respiration. With liver mitochondria isolated from fasted rats, 6 mM glutamate increased the rate of acetoacetate production from gamma-linolenoylcarnitine by 130 and 210% under state 3 and uncoupled conditions, respectively. Glutamate did not have any significant effect on the degradation of oleoylcarnitine. The proposed explanation for these findings is that the glutamate dehydrogenase reaction can function as a source of NADPH for 2,4-dienoyl-CoA reductase. 4. The degradation of gamma-linolenoylcarnitine to ketone bodies was augmented in mitochondria isolated from rats treated with clofibrate or partially hydrogenated marine oil. 5. We conclude that 2,4-dienoyl-CoA reductase is an important auxiliary enzyme in the beta-oxidation of polyunsaturated fatty acids. Induction of this enzyme by clofibrate or by certain high-fat diets increases mitochondrial capacity for the degradation of polyunsaturated fatty acids.
 ...
PMID:Beta-oxidation of polyunsaturated fatty acids having double bonds at even-numbered positions in isolated rat liver mitochondria. 686 Jun 98

The cytosolic precursor for the mitochondrial glutamate dehydrogenase of rat liver was synthesized in a cell-free reticulocyte lysate using messenger RNA from rat liver. To check whether this precursor had enzymatic activity, a highly sensitive fluorimetric method, which can measure picogram quantities of enzyme, was used together with competitive dissociation of the precursor from an immunoprecipitate with inactive glutamate dehydrogenase. Glutamate dehydrogenase activity, corresponding to that estimated from incorporation of [35S]-methionine, was detected in the precursor. The significance of this finding is discussed.
 ...
PMID:The precursor of rat liver mitochondrial glutamate dehydrogenase has enzymatic activity. 686 47

1. Activity of glutamate dehydrogenase and adenylate deaminase were measured in the livers of carnivores (animals characterised by intake of a high dietary protein). 2. Animals studied (ferret, cat, dog, hedgehog, rat, hamster, mouse, cow, pig and rabbit) were kept on their natural diet. 3. Glutamate dehydrogenase activity showed no variation between carnivores and non-carnivores. 4. Adenylate deaminase activity was significantly higher in carnivores than in non-carnivores. 5. In carnivores, adenylate deaminase might be the rate limiting enzyme in the terminal deamination of L-amino acids. 6. Elevation of adenylate deaminase might be due to the acidogenic effect of the diet.
 ...
PMID:Activity of adenylate deaminase and glutamate dehydrogenase in the liver: species and dietary variation. 708 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>