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)

Release of the endogenous transmitter, glutamate, was measured from individual cone photoreceptors using a microfluorometric technique. The assay for glutamate was conducted within the lumen of a suction pipette, and was based on the fluorometric measure of the production of NADH from NAD+. This reaction was catalyzed by glutamate dehydrogenase contained in the pipette. Upon introduction of glutamate to the pipette, an increase in the NADH fluorescence was observed, representing the stoichiometric conversion of glutamate to NADH. The fluorescent signal was quantified, allowing an estimate of glutamate release from a single cone upon depolarization. The release observed was elicited upon depolarization of the cell with extrinsic current, and was detectable simultaneous with stimulation of the cell. Depolarization-induced release of endogenous glutamate was from the synaptic pedicle of the cell, and this release decreased with subsequent stimulations. The decrease in the release could be briefly reversed by an increase in the depolarization current used, or by allowing the cell to rest for several minutes.
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PMID:Application of a fluorometric method to measure glutamate release from single retinal photoreceptors. 167 56

An enzymatic method for the determination of free glutamic acid in meat products and dried soups was collaboratively studied in 11 laboratories. In the presence of the enzyme glutamate dehydrogenase, L-glutamic acid is oxidatively deaminated by nicotinamide adenine dinucleotide (NAD) to 2-oxoglutarate. In a reaction catalyzed by diaphorase, the NADH thus formed converts 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride to a formazan, which is measured in the visible range at 492 nm. Fourteen samples (7 samples of minced sausage and 7 samples of dried cauliflower soup) with glutamate contents varying between 0.4 and 16 g/kg were included in the study. Materials were distributed to participants as blind duplicates and as split level pairs. The mean relative standard deviation (RSDR) for reproducibility for the dried soup material containing glutamate between 7 and 16 g/kg was 4.6%. RSDR values for samples of minced sausage containing glutamate at lower levels (0.4-1.3 g/kg) were between 12 and 16%.
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PMID:Enzymatic determination of free glutamic acid in dried soups and in minced sausages: NMKL collaborative study. 168 80

Developmental dynamics was investigated in the activity of glutamate dehydrogenase (GDH, E.C. 1.4.1.2.-4) and glutamine synthetase (GS, E.C. 6.3.1.2) in different parts of the digestive tract of lambs, in dependence on the age from 10 to 90 days; the goal of these investigations was to elucidate in greater detail the role of the above enzymes in nitrogen metabolism. The activity of GDH, and of the coenzymes NADH and NADPH, was followed in the digesta because simple organisms (bacteria, fungi, plants) have two glutamate dehydrogenases: they differ from each other by coenzyme specificity, unlike GDH from animal sources which can utilize both NADH coenzyme and NADPH coenzyme (Fahien et al., 1965; Frieden, 1964). The following activities of GDH and GS were found out in trials with lambs at the age of 10, 20, 30, 40 and 90 days, as to the different parts of digestive tract: in the tissues of rumen, omasum, reticulum, spleen, duodenum, jejunum, ileum, int. caecum and colon the activity of GDH (NADH) varied from 0.031 to 0.305 nkat/mg dry matter, in the digesta from 0 to 2.92 nkat/mg dry matter. An investigation of GDH (NADH, NADPH) dynamics in the digesta of lambs showed the relatively high activity of GDH (NADH) in the digesta of colon at the age of 10 days and that of GDH (NADPH) in the digesta of int. caecum. The activity of GDH (NADH) was also found to be high in the digesta of int. caecum at the age of 20 days. In that period the activity of GDH (NADH, NADPH) in the digesta of rumen, omasum and reticulum was zero.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Glutamate dehydrogenase and glutamine synthetase activity in the digestive tract in lambs in relation to age]. 168 31

An activity stain to detect glutamine transaminase K subjected to nondenaturing polyacrylamide gel electrophoresis (ND-PAGE) was developed. The gel is incubated with a reaction mixture containing L-phenyl-alanine, alpha-keto-gamma-methiolbutyrate (alpha KMB), glutamate dehydrogenase, phenazine methosulfate (PMS) and nitroblue tetrazolium (NBT). Glutamine transaminase K catalyzes a transamination reaction between phenylalanine and alpha KMB. The resultant methionine is a substrate of glutamate dehydrogenase. The NADH formed in the oxidative deamination of methionine reacts with PMS and NBT to form a blue band on the surface of the gel coincident with glutamine transaminase K activity. Cysteine S-conjugate beta-lyase activity is detected in the gel by incubating the gel with a reaction mixture containing alpha KMB (to ensure maintenance of the enzyme in the pyridoxal 5'-phosphate form), S-(1,2-dichlorovinyl)-L-cysteine (DCVC), PMS, and NBT. The products of the lyase reaction interact with PMS and NBT to form a blue dye coincident with the lyase activity. In addition, a new assay procedure for measuring cysteine S-conjugate beta-lyase activity was devised. This procedure couples pyruvate formation from DCVC to the alanine dehydrogenase reaction. Preparations of purified rat kidney glutamine transaminase K yield a single protein band on ND-PAGE (apparent Mr approximately 95,000). This band coincides with both the cysteine S-conjugate beta-lyase and glutamine transaminase K activities. Activity staining showed that homogenates of rat kidney, liver, skeletal muscle, and heart possess a glutamine transaminase K/cysteine S-conjugate beta-lyase activity with an Rf value on ND-PAGE identical to that of purified rat kidney glutamine transaminase K.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glutamine transaminase K and cysteine S-conjugate beta-lyase activity stains. 172 51

Steady-state kinetic properties of glutamate dehydrogenase from Clostridium symbiosum are reported. Rates with NADP(H) are over three hundred times lower than with NAD(H) under identical conditions. The 3-acetyl pyridine and 6-deamino adenine analogues of NAD+, on the other hand, are used almost as well as NAD+ itself. Amino acid specificity is very tight at both pH 7 and pH 9. The best alternative substrate of those tested, L-alpha-amino-gamma-nitraminobutyrate, gave only 0.5% of the rate seen with glutamate. With 400 microM NAD+ a 160-fold variation of the glutamate concentration gave a linear Eadie plot apart from slight inhibition at the highest concentrations. With 40 mM L-glutamate and varied [NAD+], the Eadie plot appeared linear between 1.6 microM and 60 microM and again between 60 microM and 2000 microM, but the slopes of the two lines differed by a factor of 8.4. This striking pattern is not attributable to impurities in the coenzyme or to changes in the state of aggregation of the enzyme. For the high concentration range (greater than 60 microM NAD+), the presence of all four linear terms in the reciprocal form of the initial rate equation indicates a sequential mechanism. Similar measurements made for APAD+ and dnNAD+ show no sign of non-linearity in the Eadie plot over the wide concentration ranges explored. In the reductive amination direction, with NADH as coenzyme, linear reciprocal plots were obtained for all three substrates. Systematic variation of concentrations led via primary, secondary and tertiary plots to all eight possible initial-rate parameters in a linear reciprocal initial-rate equation. Compulsory-order and enzyme-substitution mechanisms appear to be excluded, and a random route to the central complex seems the only possibility compatible with the results.
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PMID:Functional studies of a glutamate dehydrogenase with known three-dimensional structure: steady-state kinetics of the forward and reverse reactions catalysed by the NAD(+)-dependent glutamate dehydrogenase of Clostridium symbiosum. 176 63

The hyperthermophilic archaebacterium Pyrococcus furiosus contains high levels of NAD(P)-dependent glutamate dehydrogenase activity. The enzyme could be involved in the first step of nitrogen metabolism, catalyzing the conversion of 2-oxoglutarate and ammonia to glutamate. The enzyme, purified to homogeneity, is a hexamer of 290 kDa (subunit mass 48 kDa). Isoelectric-focusing analysis of the purified enzyme showed a pI of 4.5. The enzyme shows strict specificity for 2-oxoglutarate and L-glutamate but utilizes both NADH and NADPH as cofactors. The purified enzyme reveals an outstanding thermal stability (the half-life for thermal inactivation at 100 degrees C was 12 h), totally independent of enzyme concentration. P. furiosus glutamate dehydrogenase represents 20% of the total protein; this elevated concentration raises questions about the roles of this enzyme in the metabolism of P. furiosus.
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PMID:Extremely thermostable glutamate dehydrogenase from the hyperthermophilic archaebacterium Pyrococcus furiosus. 176 79

The maximal rate (Vmax) of some mitochondrial enzyme activities related to energy transduction (citrate synthase, alpha-ketoglutarate dehydrogenase, malate dehydrogenase, succinate dehydrogenase, NADH-cytochrome c reductase, cytochrome oxidase) and amino acid metabolism (glutamate dehydrogenase, glutamate-pyruvate transaminase and glutamate-oxaloacetate transaminase) are evaluated in non synaptic ("free") and intrasynaptic mitochondria from brain hippocampus. The different mitochondrial populations were isolated from rat subjected to single i.p. treatment with saline solution, almitrine (30 mg/kg) and delta-yohimbine (10 mg/kg). In control rats, the mitochondrial populations exhibit different enzymatic patterns. Acute treatment with almitrine decreases cytochrome oxidase activity in intra-synaptic mitochondria, while acute treatment with delta-yohimbine decreases succinate dehydrogenase activity in both types of free and intra-synaptic mitochondria. NADH-cytochrome c reductase activity is also decreased by acute treatment with almitrine ("free" and "synaptic" mitochondria) and delta-yohimbine (synaptic mitochondria only).
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PMID:Factors involved in drug interference on enzyme activities of three mitochondrial populations from rat hippocampus. 180 34

The affinity label 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 5'-triphosphate (8-BDB-TA-5'-TP) has been shown to react with bovine liver glutamate dehydrogenase in the region of the GTP-dependent NADH inhibitory site with incorporation of about 1 mol of reagent/mol of subunit [Ozturk, D. H., Safer, D., & Colman, R. F. (1990) Biochemistry 29, 7112-7118]. The modified enzyme was shown to contain only 5 free sulfhydryl groups upon 5,5'-dithiobis (2-nitrobenzoate) titration as compared with 6 in the unmodified enzyme. In the unmodified enzyme digested with trypsin, 6 cysteinyl peptides were detected by high-performance liquid chromatography upon treatment with iodo [3H]acetic acid. In contrast, only 5 (carboxymethyl)cysteinyl peptides were detected in 8-BDB-TA-5'-TP-modified enzyme. When carboxymethylated modified and unmodified enzymes were digested with thermolysin, 6 peptide sequences containing (carboxymethyl)cysteine were obtained in the unmodified enzyme, but only 5 were observed in the modified enzyme. The (carboxymethyl)cysteine which was absent in the modified enzyme was determined to be Cys-319, leading to the conclusion that 8-BDB-TA-5'-TP reacts with Cys-319, thereby preventing it from subsequent reaction with radioactive iodoacetate. It was previously reported that 6-[(4-bromo-2,3-dioxobutyl)thio]-6-deaminoadenosine 5'-diphosphate (6-BDB-TA-5'-DP) modifies Cys-319 in this enzyme [Batra, S. P., & Colman, R. F. (1986) Biochemistry 25, 3508-3515].(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of cysteine-319 as the target amino acid of 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 5'-triphosphate in bovine liver glutamate dehydrogenase. 185 24

An assay for a direct photometric determination of F XIII in untreated and undiluted plasma was developed. In a one-step procedure F XIII is activated by thrombin and Ca2+ and cross-links glycine-ethylester to a specific glutamine containing peptide substrate. The released ammonia is incorporated into alpha-ketoglutarate by glutamate dehydrogenase, and the NADH consumption of this reaction is measured photometrically at 340 nm. NADH-consumption is directly proportional to the F XIII activity. Fibrin polymerization and the corresponding turbidity is avoided by the use of a fibrin aggregation inhibitor. The procedure is rapid and simple and enables to measure within the range of 0 to 150% F XIII. It can be performed with automated analyzers as well as with common photometric equipment. The normal range of F XIII activity in 167 healthy donors was determined to be 70 to 140%.
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PMID:A photometric assay for blood coagulation factor XIII. 187 15

A radioisotopic procedure for the assay of 3-hydroxybutyrate is presented. It is based on the measurement of NADH, generated in the 3-hydroxybutyrate dehydrogenase reaction, through the conversion of 2-[U-14C]ketoglutarate to 14C-labeled L-glutamate in the presence of beef liver glutamate dehydrogenase. The assay is linear in the range of 2.5 to 20.0 pmole/sample and about 100-times more sensitive than previous methods. The procedure proved useful for the measurement of 3-hydroxybutyrate in liver samples not exceeding 25 micrograms wet weight.
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PMID:Assay of 3-hydroxybutyrate in the picomolar range. 188 29


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