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)

NADH substrate inhibition of bovine liver glutamate dehydrogenase appears to be eliminated at enzyme concentrations above 0.5mg/ml. Since the inhibition cannot be restored by preincubation of the enzyme with any substrate or product combination, the release of inhibition had previously been considered the result of enzyme polymerization. Benzene-saturated solutions, however, increase the extent of enzyme polymerization without affecting the NADH inhibition. These and related control measurements demonstrate that the release of substrate inhibition is the result of a hysteretic transition of an enzyme central and transitory complex.
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PMID:Hysteretic nature of NADH substrate inhibition of bovine liver glutamate dehydrogenase. 21 66

Histochemical studies of some myocardial oxido--reductive enzymes after a beta--adrenergic blockade with propranolol have been carried out. Succinate, isocitrate and glucose-6-phosphate dehydrogenases did not indicate any changes in activity, whereas the changes in reaction intensities concerning NADH and NADPH tetrazole reductases and glutamate dehydrogenase have rather a transitory and reversible character. Only lactate dehydrogenase showed an increase in the enzymatic activity which speaks for an increase in the glycolysis process in the heart muscle. In the light of our own presented research results we assume that the experimental beta--adrenergic blockade of the heart muscle in rats does not evoke more important enzymatic changes which are noticeable in histochemical microscope examination.
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PMID:Histochemical studies of some myocardial oxido-reductive enzymes after experimental beta-adrenergic blockade with propranolol. 21 81

Membrane vesicles isolated from Escherichia coli ML 308--225 have been analyzed by crossed immunoelectrophoresis, and immunoprecipitates corresponding to the following cellular components have been identified: ATPase (EC 3.6.1,3), two or three NADH dehydrogenases (EC 1.6.99.3), D-lactate dehydrogenase (EC 1.1.1.27), glutamate dehydrogenase (EC 1.4.1.4), dihydro-orotate dehydrogenase (EC 1.3.3.1), 6-phosphogluconate dehydrogenase (EC 1.1.1.43), polynucleotide phosphorylase (EC 2.3.7.8), beta-galactosidase (EC 3.2.1.23), lipopolysaccharide, and Braun's lipoprotein. The cellular origin of many of the vesicle immunogens is determined, and Braun's lipoprotein is used as a marker to quantitate the extent of outer membrane contamination (less than 3%). Membrane antigens are also characterized with regard to their amphiphilic or hydrophilic properties by charge-shift crossed immunoelectrophoresis. Furthermore, the following immunogens cross-react with components in membrane vesicles prepared from Salmonella typhimurium: one of the three NADH dehydrogenases, ATPase, polynucleotide phosphorylase, 6-phosphogluconate dehydrogenase, Braun's lipoprotein, and three unidentified antigens. In the accompanying paper [Owen, P., & Kaback, H. R. (1979) Biochemistry 18 (following paper in this issue)] quantitative immunoadsorption is utilized to establish the topology of the vesicles with respect to the distribution of antigens on the inner and outer faces of the membrane.
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PMID:Immunochemical analysis of membrane vesicles from Escherichia coli. 21 20

Serum glutamic oxaloacetic transaminase (GOT), mitochondrial GOT (GOTm), glutamic-pyruvic transaminase (GPT) and glutamate dehydrogenase activities were determined in 43 healthy controls and in 280 cases of liver diseases. A simplified column chromatographic method coupled with UV assay was employed for separation of GOTm. The activity was measured by following decrease in abosrbance of NADH at 340 nm. The lowest activity of GOTm determined with a coefficient of variation below 10% was 6 mIU/ml. High GOTm activities were found in acute hepatitis (acute stage), subacute hepatitis and primary biliary cirrhosis and were generally associated with high total GOT (GOTt) activities. The activity ratio of GOTm/GOTt varied depending on the stage and severity of liver diseases. The GOTm/GOTt ratio was decreased in acute, fulminant and subacute hepatitides. No significant reduction in the ratio was found in bile duct obstruction, alcoholic liver injury or metastatic liver cancer. Although relatively high GOTm/GOTt ratios were found in some patients with severe hepatic injury, they had no definite association with poor prognosis. These results indicate that the marked elevation in GOTt over GPT in advanced chronic hepatitis, liver cirrhosis and primary hepatoma was mainly due to preferential leakage of cytoplasmic GOT (GOTs).
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PMID:The mechanism of the release of hepatic enzymes in various liver diseases. 1. Alterations in cytoplasmic and mitochondrial enzyme activities in serum. 22 31

The changes induced by phenobarbital in cerebral enzymatic activities of the Krebs' cycle (citrate synthase, malate dehydrogenase) and electron transfer chain (total NADH-cytochrome c reductase and cytochrome oxidase) were studied. In addition, the activity of lactate dehydrogenase of acetylcholine esterase and of glutamate dehydrogenase was also studied. These enzymatic activities were evaluated in the homogenate in toto and in a crude mitochondrial fraction from rat brain. The modifications in some of these activities indicate that several new metabolic situations occur in brain tissue after phenobarbital treatment.
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PMID:Effect of phenobarbital on cerebral energy state and metabolism. Enzymatic activities. 23 Jun 18

The sequential pattern of lipid accumulation and associated biochemical changes were studied in two commonly used experimental models of nutritional fatty liver in rats. Female rats were maintained for 8 weeks on high fat, low protein diets containing adequate methionine and choline, and drinking water ad libitum (Diet 1), or deficient in methionine and choline and containing 20% ethanol as a substitute for drinking water (Diet 2). Histologically, there was a progressive increase in liver lipids, mainly in the periportal areas. Occasional foci of liver cell necrosis with lipogranuloma formation occurred in areas of severe fatty change. These changes appeared earlier and were more marked in rats maintained on Diet 2. Electron micrographs revealed large lipid droplets in the liver cells, which sometimes contained myelin figures. The mitochondria were enlarged, distorted and appeared as amorphous structures with disorientated cristae in rats on Diet 1, whereas they had a condensed conformation in rats maintained on Diet 2. Rough endoplasmic reticulum was fragmented and degranulated particularly in rats on Diet 1, and smooth endoplasmic reticulum showed hyperplasia and vesiculation in rats on Diet 2. There was a progressive increase in the total liver lipids and triglycerides in both the groups of rats. This fatty change was accompanied by a significant increase in hepatic 3-hydroxybutyrate, acetoacetate, malate, 2-oxoglutarate, citrate, lactate, ammonia, glutamate, alanine and aspartate, and a significant decrease in oxaloacetate, urea and glucose concentrations. The mass action ratios for alanine aminotransferase, aspartate amino transferase, and glutamate dehydrogenase, generally moved in a parallel direction. Hepatic ATP content was considerably reduced accompanied by a decrease in [ATP]/[ADP] ratios and a significant increased in [lactate]/[pyruvate] and [3-hydroxybutyrate]/[acetoacetate] ratios. There was a corresponding decrease in the [NAD+]/[NADH] ratios both in the cytoplasmic and mitochondrial compartments. These biochemical changes were particularly severe in rats maintained on Diet 1 and Diet 2 for 8 weeks. There was a very good relationship between impaired mitochondrial and endoplasmic reticulum functions, redox and phosphorylation states, and the relevance of their changes to the fate of fatty liver cells.
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PMID:Lipid accumulation in the rat liver: a histological and biochemical study. 23

Using the semi-continuous cultivation technique we could establish that specifically in Streptomyces noursei JA 3890b during growth on a medium supplied with D,L-alanine, NH4+, and maize starch there are two different phenotypes of the organism and stationary states of metabolism, respectively. The expression of either the metabolic state I with an enhanced capacity to oxidative deamination of alanine via the NAD+-dependent alanaine dehydrogenase or the metabolic state 2 which may be characterized by the preferred use of ammonium ions via the NADP+-dependent glutamate dehydrogenase was shown to depend strongly on the conditions of inoculum cultivation. When the amino acid permeases were derepressed by cultivating the inoculum cells on amino acid media, probably due to the defective mechanism of negative feedback control of amino acid influx in this strain an abnormously high uptake of alanine was observed that, consequently, was correlated to the enhanced oxidation of this amino acid as well as to the intensive production of ammonia within the cell. This overproduction of cellular NH4+ seems to bring about the subsequent repression of biosynthetic glutamate dehydrogenase and so on the accumulation of ammonia autocatalytically may rise up (metabolic state I). On the other hand, if the influx of alanine was kept low and the NADH oxidation was less efficient, respectively, or when there was high cellular activity of glutamate dehydrogenase the level of ammonia never did exceed the respressory limit and, accordingly, the expression of the metabolic state 2 was observed. Switching-over of metabolic flux from the state 2 towards the state 1 can be brought about either by increasing the level of nitrogen sources in the medium or by adding buffers pH greater than 7.5. In contrast, decrease of cellular level of NH4+ was shown to induce the transition of metabolic state 1 into the state 2. This can be achieved not only by limitation of nitrogen source but also by adding different aminobenzoic acids and, alternatively, effectors of membrane function (short-chain alcohols), inhibitors of cytochrome oxidases (sodium azide, potassium cyanide), heavy metal (Fe++)-chelating agents (catechol, 2,5'-dipyridyl, o-phenanthroline), beta-alanine, and buffers pH less than 7. This suggests that these effectors are capable of preventing the abnormously high influx of amino acids as well as its wasteful catabolism within the cell of S. noursei JA 3890b. Therefore, it seems likely that by this way the aminobenzoic acids and similar effectors can diminish the catabolite repression or inhibition of secondary metabolism by cellular excess of some nitrogen compounds in good agreement with its well-known stimulatory action on the biosynthesis of the antibiotic nourseothricin in this strain.
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PMID:Regulative influence of o-aminobenzoic acid on the biosynthesis of nourseothricin in cultures of Streptomyces noursei JA 3890b. IV. Bistability of metabolism and the mechanism of action of aminobenzoic acids. 23 65

Methods are described in which liberation of ammonia from amino acid substrates by the D- and L-amino acid oxidases may be coupled with the NADH-dependent reductive amination of 2-oxoglutarate catalysed by exogenous glutamate dehydrogenase (L-glutamate: NAD oxidoreductase (deaminating), EC 1.4.1.2). The inhibition of D-amino acid oxidase (D-amino acid:O2 oxidoreductase (deaminating), EC 1.4.3.3) by ADP needed to activate and stabilise glutamate dehydrogenase was relieved by FAD, and the substrate was D-alanine at approximately 6-fold Km concentration. Neither FAD or FMN were required in the L-amino acid oxidase (L-amino acid:O2 oxidoreductase (deaminating), EC 1.4.3.2) assay; this utilised L-leucine as substrate in a concentration approximately 7-fold the Km value. The methods were reasonably sensitive and precise, and a linear relationship between activity and enzyme concentration prevailed up to an absorbance change of 0.050 per min. They have the advantage of being amenable to automation and to employment of fluorescence techniques should greater sensitivity be required.
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PMID:Coupled optical rate determinations of amino acid oxidase activity. 23 96

Neurospora glutamate dehydrogenase (NADP-specific) is rapidly inactivated upon reaction with tetranitromethane. This inactivation is completely prevented by the presence of coenzyme (NADP) or nicotinamide mononucleotide (NMN) but not by substrate. NADH, or 2'-monophosphoadenosine-5'-diphosphoribose. Amino acid analysis indicates that the primary effect of modification is nitration of a single residue of tyrosine per polypeptide chain. We have identified the reactive tyrosine by isolation of a single, uniquely labeled peptide after hydrolysis with trypsin followed by cleavage with cyanogen bromide. The modified residue proved to be tyrosine-168 in the linear sequence. This residue is not present in the part of the sequence that had been previously implicated as involved in the binding of the adenylate portion of the coenzyme. Both NMN and 2-monophosphoadenosine-5'-diphosphoribose act as competitive inhibitors of NADP in the oxidation of glutamate with Ki values of 4.65 x 10(-4) M and 4.30 x 10(-4) M, respectively. Thus, the specific protection afforded by NADP and NMN, but not by 2'-monophosphoadenosine-5'-diphosphoribose, indicates that tyrosine-168 is involved in binding the nicotinamide portion of the coenzyme.
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PMID:Nicotinamide adenine dinucleotide phosphate-specific glutamate dehydrogenase of Neurospora. III. Inactivation by nitration of a tyrosine residue involved in coenzyme binding. 23 46

A method is described for determining the activity of deoxycytidylate deaminase in serum. The ammonia liberated from deoxycytidine monophosphate has been specifically determined by enzymatic amination of alpha-ketoglutarate using glutamate dehydrogenase. The concurrent oxidation of NADH2 at 340 nm was proportional to the ammonia liberated from deoxycytidine monophosphate. Using the technique described, a result would be available to the clinician in under 4.5 h. The "normal activity" for deoxycytidine deaminase in normal male, female and pregnancy sera has been determined.
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PMID:A rapid method for the determination of deoxycytidylate deaminase activity in pregnancy serum. 24 May 23


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