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 maximal rates (Vmax) of some enzyme activities related to synaptosomal energy metabolism were studied in different types of synaptosomes from cerebellar cortex of Macaca Fascicularis (Cynomolgus monkey). Different synaptosomal populations, namely "large" and "small" synaptosomes, were isolated from the anterior lobule of the cerebellar cortex of monkeys treated p.o. with dihydroergocriptine at the dose of 12 mg/kg/day before and during the induction of a Parkinson's-like syndrome by MPTP administration (i.v., 0.3 mg/kg/day for 5 days). The enzymes were chosen according to their regulatory role and as markers of the following metabolic pathways: (a) glycolysis ((hexokinase, phosphofructokinase, lactate dehydrogenase), (b) Krebs' (TCA) cycle (citrate synthase, malate dehydrogenase), (c) amino acid, glutamate metabolism (glutamate dehydrogenase, glutamate-pyruvate- and glutamate-oxaloacetate-transaminases), (d) acetylcholine catabolism (acetylcholinesterase) and (e) ATPases, i.e. Na(+)-K(+)-ATPase, Mg(2+)-ATP synthetase, Mg(2+)-ATPase, Ca(2+)-Mg(2+)-ATPase and Ca(2+)-ATPase Low and High affinity for Ca2+. The MPTP administration modified the activities of citrate synthase, malate dehydrogenase, Na(+)-K(+)-ATPase, acetylcholinesterase and glutamate-oxaloacetate transaminase only on selected types of synaptosomes. Pharmacological treatment by dihydroergocriptine was able to recovery at the steady-state levels the activities of these enzymes, thus demonstrating a partial protective effect on these biochemical parameters.
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PMID:Parkinson-like disease by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity in Macaca fascicularis: synaptosomal metabolism and action of dihydroergocriptine. 817 63

Glutamate dehydrogenase (L-glutamate:NADP+ oxidoreductase, deaminating and transaminating, EC 1.4.1.4) was purified to homogeneity from the extremely thermophilic archaebacterial isolate AN1 (a member of the Thermococcales). The enzyme comprised a large proportion of the soluble cell protein (11%) and was purified in high yield. The molecular mass of the native enzyme was 204 kDa, while the subunit molecular mass was 47 kDa, indicating a tetrameric structure. The enzyme is specific for NADP(H) rather than NAD(H) by a factor of greater than 1000, as judged by Vmax/Km. Glutamate synthase activity was about 50% of the glutamate dehydrogenase activity. Activity was markedly enhanced by calcium, magnesium and manganese ions. The enzyme was highly thermostable with t1/2 values of 12.5 h and 47 min at 90 degrees C and 103 degrees C, respectively.
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PMID:Glutamate dehydrogenase from the extremely thermophilic archaebacterial isolate AN1. 839 86

Photoaffinity labeling with [alpha-32P]8N3GTP and [gamma-32P]8N3GTP was used to identify the guanine binding domain of the GTP regulatory site within glutamate dehydrogenase (GDH). Without photolysis, 8N3GTP mimicked the regulatory properties of GTP on GDH activity with 8N3GTP exhibiting a Ki of 5 microM while the Ki for GTP was about 0.6 microM. Under optimal photolabeling conditions saturation of photoinsertion with 1 microgram of GDH revealed an apparent Kd of 9 +/- 4 microM for [gamma-32P]8N3GTP. Photolabeling with this analog could be competitively inhibited with GTP with an apparent Kd of 12 +/- 2 microM. Other nucleotides such as ATP and NAD(P)H could not reduce the amount of photoinsertion as effectively as GTP. ADP could decrease photoinsertion, but only at much higher concentrations. NAD(P)+, GDP, AMP, and GMP had little effect on photoinsertion. Divalent cations Mg2+ and Ca2+ also reduced photoinsertion significantly while the monovalent K+ and Na+ ions had no effect. Aluminum(III)-chelate or iron(III)-chelate affinity chromatography and reversed-phase HPLC were used to purify photolabel-containing peptides generated with either trypsin or chymotrypsin. This identified a portion of the guanine binding domain within the GTP regulatory site as the region containing the sequence Ile439 to Tyr454. Photolabeling of this peptide was prevented 91% by the presence of 300 microM GTP during photolysis. Lys445 was not identified in sequence analyses of the photolabeled peptides. Also, trypsin was unable to cleave the photolabeled peptide at this site. These results suggest that Lys445 may be the residue modified by [alpha-32P]8N3GTP.
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PMID:Identification of a guanine binding domain peptide of the GTP binding site of glutamate dehydrogenase: isolation with metal-chelate affinity chromatography. 843 45

The effect of oral intake of endotoxins was studied in 12 prepubertal gilts. The animals were given 30 or 100 mg of ET each in their regular morning feed ration. Blood samples were collected periodically during 24 h and the clinical status, including rectal temperature, was recorded at the same time. Hematological and clinical chemical analyses that included serum bile acids, glutamate dehydrogenase, alkaline phosphatase, calcium, iron, zinc and a blood plasma metabolite of prostaglandin F2 alpha, were done. The animals showed no obvious clinical symptoms following endotoxin feeding. The major findings were increased bile acid and glutamate dehydrogenase values with the most prominent rises being recorded 10-12 h after endotoxin intake. In a later experiment, 6 animals were injected i.v. with endotoxin in doses in the range 0.1-0.5 micrograms/kg b.w. Blood samples were taken and analysed as in the endotoxin-feeding experiment. Within 1 h of injection, all animals showed symptoms such as vomiting, fever and dyspnea. The clinical signs disappeared within 2-5 h. The injections were followed by increases in bile acids, glutamate dehydrogenase and prostaglandin F2 alpha metabolite. To conclude, this study indicates that clinically healthy prepubertal gilts react to ingested endotoxin in feed but that no apparent clinical disturbances ensue.
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PMID:Effects of oral and intravenous administration of endotoxin in prepubertal gilts. 845 2

In the period of March 1988-March 1989, in 20 Lower Austrian sheep breeding farms blood samples were taken in two-month intervals from sheep of the following breeds: 130 Tyrolean Mountain sheep, 59 German Improved Land breed, 59 East Friesian and 57 German Blackheaded Mutton breed sheep. The following standards for sheep were evaluated: Erythrocytes 7,2-11,9 T/L, haematocrit 0,25-0,41 1/L, haemoglobin 82-147 g/L, lymphocytes 34-80%, segmented neutrophils 10-53%, band neutrophils 1-3%, eosinophilic granulocytes 0-24%, basophilic granulocytes 0-1%, monocytes 0-1%, calcium 1,8-2,8 mmol/L, phosphorus 1,0-2,6 mmol/L, magnesium 0,6-1,3 mmol/L, total protein 53-81 g/L, albumin 22-41 g/L, aspartate aminotransferase 27-81 U/L, alanine aminotransferase 3-25 U/L, gamma glutamic transaminase 24-59 U/L, alkaline phosphatase 44-355 U/L, creatine kinase 3-130 U/L, glutamic dehydrogenase 2,0-36,5 U/L, total bilirubin 0,7-5,1 mumol/L, cholesterol 1,1-3,2 mmol/l, urea nitrogen 1,3-12,7 mmol/l, creatinine 50-112 mumol/L. Apart from that, additional standards for the mentioned breeds of sheep were evaluated, revealing significant differences. Also the age and the time of the year proved to have an influence upon the ascertained blood values.
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PMID:[The hematologic parameters, concentrations of minerals and metabolic products and activities of enzymes in sheep]. 847 Oct 13

The activities of hexokinase isoenzymes, lactate dehydrogenase, cytosolic NAD-linked glycerophosphate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, and glutamate dehydrogenase were measured in homogenates of rat purified pancreatic B and non-B islet cells. In B cell homogenates, the maximal activity of hexokinase and glucokinase was one to two orders of magnitude lower than that of lactate dehydrogenase. The activity of the mitochondrial FAD-linked glycerophosphate dehydrogenase was also much lower than that of the cytosolic NAD-linked glycerophosphate dehydrogenase . A comparable hierarchy in the activity of these enzymes was observed in non-B islet cells. These findings reinforce the view that the preferential stimulation of oxidative glycolysis observed in insulin-producing cells, when exposed to high concentrations of D-glucose, is attributable to a Ca2+-induced activation of the mitochondrial FAD-linked glycerophosphate dehydrogenase, rather than to saturation of the catalytic activity of lactate dehydrogenase.
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PMID:Relevance of lactate dehydrogenase activity to the control of oxidative glycolysis in pancreatic islet B-cells. 861 12

We established a simple and rapid kinetic assay for measurement of calcium in serum by using urea amidolyase (EC 3.5.1.45) from yeast species. The method is based on inhibition of the enzyme by calcium. In the assay, we eliminated endogenous ammonium ion by use of glutamate dehydrogenase (GLDH; EC 1.4.1.4); then in the presence of urea amidolyase, urea, ATP, bicarbonate, magnesium, and potassium ions, ammonium ion production was inversely proportional to calcium ion concentration in serum. The concentration of ammonium ion formed was determined by adding GLDH to produce NADP+ in the presence of 2-oxoglutarate and NADPH; we then monitored the change of absorbance at 340 nm. The within-run CVs of this method were 1.7-3.2% (n = 10) at 1.53-3.08 mmol/L, respectively. Day-to-day (total) CVs were 2.8-4.1%. Analytical recovery was 92-112%. The presence of other ions, ascorbic acid, reduced glutathione, bilirubin, hemoglobin, citrate, lipemic material, or human serum albumin did not affect this assay system. The correlation between values obtained with our method (y) and o-cresolphthalein complexone method (CPC) (x) was: y = 1.001x + 0.077 mmol/L (r = 0.949, Sy[symbol: see text]x = 0.079, n = 100); with the other enzymatic method (x) it was: y = 0.952x + 0.021 mmol/L (r = 0.955, Sy[symbol: see text]x = 0.074, n = 100). The SEs for each method were: 0.025 mmol/L, our method; 0.023 mmol/L, CPC method; and 0.025 mmol/L, the other enzymatic method.
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PMID:New enzymatic assay for calcium in serum. 869 77

1. The effects of lifarizine (RS-87476) on intracellular Ca2+ rises and the release of glutamate from rat cerebrocortical synaptosomes depolarized with 30 mM KCl were investigated by use of entrapped fura 2 and exogenous glutamate dehydrogenase. 2. Prior (1 min) addition of lifarizine decreased 30 mM KCl-induced total glutamate release, with 3 microM and 10 microM causing 39% and 72% averaged decreases from controls. The calcium-dependent component of glutamate release (approx. 40% of total) was similarly decreased by 47% and 74%, whereas the calcium-independent component was decreased by only 32% and 43% respectively. 3. In parallel experiments with fura-2-loaded synaptosomes, lifarizine reduced the depolarization-induced increases in intracellular [Ca2+], suggesting that this is the means by which the decreases in glutamate release are brought about. Lifarizine inhibited both the plateau and the spike phases of the Ca2+ increases suggesting that, in addition to its known sodium channel blocking properties, it may also inhibit more than one class of calcium channel in the synaptosomes. 4. Lifarizine at 1 microM and 3 microM also inhibited the rises in intracellular [Ca2+] in rat cultured cortical neurons depolarized with 60 mM KCl. 5. These effects of lifarizine on intracellular Ca2+ and glutamate exocytosis may contribute to its neuroprotective action.
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PMID:Inhibition by lifarizine of intracellular Ca2+ rises and glutamate exocytosis in depolarized rat cerebrocortical synaptosomes and cultured neurones. 873 90

Ten scientific organizations formed a joint international committee to provide expert recommendations for clinical pathology testing of laboratory animal species used in regulated toxicity and safety studies. For repeated-dose studies in rodent species, clinical pathology testing is necessary at study termination. Interim study testing may not be necessary in long-duration studies provided that it has been done in short-duration studies using dose levels not substantially lower than those used in the long-duration studies. For repeated-dose studies in nonrodent species, clinical pathology testing is recommended at study termination and at least once at an earlier interval. For studies of 2 to 6 weeks in duration in nonrodent species, testing is also recommended within 7 days of initiation of dosing, unless it compromises the health of the animals. If a study contains recovery groups, clinical pathology testing at study termination is recommended. The core hematology tests recommended are total leukocyte (white blood cell) count, absolute differential leukocyte count, erythrocyte (red blood cell) count, evaluation of red blood cell morphology, platelet (thrombocyte) count, hemoglobin concentration, hematocrit (or packed cell volume), mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration. In the absence of automated reticulocyte counting capabilities, blood smears from each animal should be prepared for reticulocyte counts. Bone marrow cytology slides should be prepared from each animal at termination. Prothrombin time and activated partial thromboplastin time (or appropriate alternatives) and platelet count are the minimum recommended laboratory tests of hemostasis. The core clinical chemistry tests recommended are glucose, urea nitrogen, creatinine, total protein, albumin, calculated globulin, calcium, sodium, potassium, total cholesterol, and appropriate hepatocellular and hepatobiliary tests. For hepatocellular evaluation, measurement of a minimum of two scientifically appropriate blood tests is recommended, e.g., alanine aminotransferase, aspartate aminotransferase, sorbitol dehydrogenase, glutamate dehydrogenase, or total bile acids. For hepatobiliary evaluation, measurement of a minimum of two scientifically appropriate blood tests is recommended, e.g., alkaline phosphatase, gamma glutamyltransferase, 5' -nucleotidase, total bilirubin, or total bile acids. Urinalysis should be conducted at least once during a study. For routine urinalysis, an overnight collection (approximately 16 hr) is recommended. It is recommended that the core tests should include an assessment of urine appearance (color and turbidity), volume, specific gravity or osmolality, pH, and either the quantitative or semiquantitative determination of total protein and glucose. For carcinogenicity studies, only blood smears should be made from unscheduled sacrifices (decedents) and at study termination to aid in the identification and differentiation of hematopoietic neoplasia.
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PMID:Harmonization of animal clinical pathology testing in toxicity and safety studies. The Joint Scientific Committee for International Harmonization of Clinical Pathology Testing. 874 16

The role of endogenous mitochondrial Mg2+ as a potential regulator of mitochondrial dehydrogenase activity, and therefore of cellular respiration, was measured in isolated mitochondria containing matrix Ca2+ and Mg2+ levels resembling those occurring in vivo. Ca2+ and Mg2+ depletion was carried out using the cation ionophore A23187 in the presence or absence of the Ca2+ uniporter inhibitor ruthenium red (RR). Divalent cation depletion inhibits the oxidation of alpha-ketoglutarate or pyruvate in states 4 and 3, slows uncoupled respiration and results in decreased membrane potential. Since the addition of Mg2+ could not restore respiration, these dehydrogenases appear not to be regulated by Mg2+. In contrast, similar cation depletion stimulates succinate dehydrogenase (or glutamate dehydrogenase) in state 4 without decreasing membrane potential. The addition of RR caused authentic uncoupling, accompanied by a decrease in membrane potential and an increase in membrane permeability. These effects could be completely reversed by Mg2+. These and other data, showing that Mg2+ depletion results in a change of respiration depending on the substrate oxidized and the metabolic state, indicate that Mg2+ removal may have direct and indirect effects on mitochondrial respiration. A clear direct effect is the stimulation of succinate or glutamate dehydrogenase by decreasing matrix Mg2+. Hence, changes in matrix Mg2+ (in addition to those of Ca2+) could be of great consequence, not only for the control of respiration but also for metabolic pathways affected by changes in concentrations of matrix substrates.
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PMID:Mg2+ control of respiration in isolated rat liver mitochondria. 884 Nov 28


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