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)

Use of the gel film technique in microphotometric determinations of enzyme activity is described. The microscope photometer is computer-controlled. It is programmed to deal with repetitive measurements at up to 12 selected positions within a tissue section and to evaluate recorded reaction rates statistically. Films of polyacrylamide gel with entrapped glucose-6-phosphate dehydrogenase are used as a model to demonstrate the correlation between local enzyme activity and the microphotometrically determined reaction rate. Enzyme activities at different positions in the same tissue section are determined and compared. Activity profiles of five enzymes (glutamate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, succinate dehydrogenase, NAD-dependent tetrazolium reductase) in the liver are presented and show non-uniform intra-acinar distribution patterns. These results are interpreted in the light of the metabolic zonation of the hepatic acinus. Further applications of the method are discussed.
 ...
PMID:Microphotometric determination of enzyme activities in cryostat sections by the gel film technique. 26 70

In a detailed study focused on the methodological problems in dehydrogenase histochemistry [e.g., fixation, diffusion of enzymes and of reduced inermediates, conversion of NADPH and NADP to NADH and NAD, respectively, penetration of tetrazolium salt and formazan substantivity, 'nothing dehydrogenase' reaction, use of exogenous CoQ10 and of flavoprotein substitute (PMS)], the distribution and activity of succinate dehydrogenase, NAD(P)H-tetrazolium reductase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase (H and M types), and of L-glutamate dehydrogenase (E.C.1.4.1.2 and E.C.1.4.1.3) have been investigated in the rat cerebellum. It was evident from the study that reliable results could only be obtained if all the aforementioned factors had been considered. The image of actual concentration of SDH in the neuropil of the molecular layer could only be recorded by adding CoQ10, while other structures exhibited greater balance between SDH and endogenous mitochondrial CoQ. Contrary to previous studies, a reversed localization of the activity of G-6-PDH and LDH was noticed. The elements of molecular and Purkinje layers were rich in G-6-PDH, while the granular layer was nearly depleted. The actual level of LDH could only be recorded if NADH-tetrazolium reductase was bypassed with PMS. The H and M types of LDH coexisted in the three cortical layers, the H type being prevalent and the M type attaining its highest level in synaptic glomeruli followed by the structures of the molecular layer and the Purkinje cells. High activity of GDH was noticed in Bergmann glia followed by synaptic glomeruli, while most other structures showed weak to moderate activity. The two GDH types coexisted in all structures showing activity, except for Bergmann cells, which only showed presence of the E.C. 1.4.1.3 type. Furthermore, Bergmann glia was exceptional by showing no activity of SDH and LDH, but strong activity of G-6-PDH and NADPH-tetrazolium reductase. The granular cells were exceptional by showing weak or no activity of all enzymes in question.
 ...
PMID:Methodological aspects of the histochemical localization and activity of some cerebellar dehydrogenases. 66 87

Using the Hep G2 cell line as a model for the human hepatocyte the question was studied whether Hep G2-peroxisomes could be able to synthesize cholesterol. Hep G2 cell homogenates were applied to density gradient centrifugation on Nycodenz, resulting in good separation between the organelles. The different organelle fractions were characterized by assaying the following marker enzymes: catalase for peroxisomes, glutamate dehydrogenase for mitochondria and esterase for endoplasmic reticulum. Squalene synthase activity was not detectable in the peroxisomal fraction. Incubation of Hep G2 cells with U18666A, an inhibitor of the cholesterol synthesis at the site of oxidosqualene cyclase, together with heavy high density lipoprotein, which stimulates the efflux of cholesterol, led to a marked increase in the activity of squalene synthase as well as HMG-CoA reductase, whereas no significant effect on the marker enzymes was observed. Neither enzyme activity was detectable in the peroxisomal density gradient fraction, suggesting that in Hep G2-peroxisomes cholesterol synthesis from the water-soluble early intermediates of the pathway cannot take place. Both stimulated and non-stimulated cells gave rise to preparations where squalene synthase activity was comigrating with the reductase activity at the lower density side of the microsomal fraction; however, it was also present at the high density side of the microsomal peak, where reductase activity was not detected.
 ...
PMID:Subcellular localization of squalene synthase in human hepatoma cell line Hep G2. 131 47

Glutamate is a major source of energy for Fusobacterium species but its mode of catabolism has not hitherto been elucidated. Cell suspensions of F. nucleatum and F. varium, as representative species from the oral cavity and gastrointestinal tract, respectively, both decarboxylated position-labelled glutamate but by different pathways. 14CO2 was released only from C-5 by F. nucleatum whereas F. varium decarboxylated glutamate at either C-1 or C-5. In both species, 2 mols of glutamate fermented yielded 2 mols of acetate and 1 mol of butyrate, suggesting the possibility of three metabolic pathways: the 2-oxoglutarate, mesaconate and 4-aminobutyrate pathways. Enzymes representative of the three pathways were assayed for in cell-free extracts of fusobacteria. All species tested possessed high levels of both glutamate dehydrogenase and 2-oxoglutarate reductase, indicating the presence of the 2-oxoglutarate pathway. Enzymes representative of the mesaconate pathway were detected in F. sulci, F. ulcerans, F. mortiferum and F. varium, while the latter two species also possessed the 4-aminobutyrate pathway. The pathways of glutamate catabolism therefore bore no relationship to the site of isolation of the fusobacteria tested but instead correlated with their chemotaxonomic properties. Thus, F. varium, F. mortiferum, F. ulcerans and F. sulci, which possess a peptidoglycan structure based on diaminopimelic acid, have either two or three pathways for glutamate catabolism whereas F. nucleatum and other species that have a lanthionine-based murein metabolized glutamate solely by the 2-oxoglutarate pathway.
 ...
PMID:Pathways of glutamate catabolism among Fusobacterium species. 167 5

Rapid identification of Fusobacterium spp. is hampered by their inability to ferment carbohydrates and the availability of relatively few useful phenotypic characters. In an attempt to identify new diagnostic markers for species, we reported recently the potential utility of glutamate dehydrogenase (GDH) electrophoretic mobilities for distinguishing eight species of Fusobacterium. We have extended these observations to include all recognised members of the genus except F. prausnitzii and F. perfoetens, and our results show that they cluster into three broad electrophoretic groups. Some species, such as F. periodonticum, F. simiae and F. necrophorum, possessed GDH with similar electrophoretic mobilities. However, within such clusters, the electrophoretic migration of 2-oxoglutarate reductase (OGR) distinguished between species. Neither GDH or OGR mobility alone clearly differentiated all species, but their combined use provided unambiguous discrimination of all species except F. varium and F. mortiferum. The DNA base compositions of all species except F. naviforme (ATCC 25832) and F. sulci, were within the range 26-34 mol% G + C, suggesting the genus may be homogeneous. However, the peptidoglycan composition divided the genus into two major groups that contained either lanthionine or diaminopimelic acid; F. mortiferum peptidoglycan contained both dibasic amino acids.
 ...
PMID:Identification of Fusobacterium species by the electrophoretic migration of glutamate dehydrogenase and 2-oxoglutarate reductase in relation to their DNA base composition and peptidoglycan dibasic amino acids. 225 Feb 88

Selected aspects of the metabolism of Plasmodium falciparum are reviewed, but conclusions based on the study of other species of plasmodia are intentionally not included since these may not be applicable. The parasites increase glucose consumption 50-100 fold as compared to uninfected red cells; most of the glucose is metabolized to lactic acid. The parasite contains a complete set of glycolytic enzymes. Some enzymes such a hexokinase, enolase and pyruvate kinase are vastly increased over corresponding levels in uninfected red cells. However, the pathway for synthesizing 2,3-diphosphoglycerate (2,3-DPG) is absent. Parasitized red cells show a decline in the concentration of 2,3-DPG which may function as an inhibitor for certain essential enzyme pathways. Pentose shunt activity is increased in absolute terms, but as a percent of total glucose consumption, there is a decrease during parasite infection of the red cell. The parasite contains a gene for G6PD and can produce a small quantity of parasite-encoded enzyme. It is not clear if the production of this enzyme can be up-regulated in G6PG deficient host red cells. The NADPH normally produced by the pentose shunt can be obtained from other parasite pathways (such as glutamate dehydrogenase). NADPH may subserve additional needs in the infected red cell such as driving diribonucleotide reductase activity--a rate limiting enzyme in DNA synthesis. The role of NADPH in protecting the parasite-red cell system against oxidative stress (via glutathione reduction) remains controversial. Parasitized red cells contain about 10 times more NAD(H) than uninfected red cells, but the NADP(H) content is unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Plasmodium falciparum carbohydrate metabolism: a connection between host cell and parasite. 225 22

An incubation medium was established for the microphotometric demonstration of glutamate dehydrogenase (Gldh) in cryostat sections of the rat hippocampus which served as an exemplary brain region. The final incubation medium consisted of 100 mM L-glutamic acid monosodium salt, 5 mM NAD, 10 mM sodium azide (NaN3), 5 mM ADP, 20 mM sodium chloride, 0.15 mM phenazine methosulfate (PMS), 5 mM nitroblue tetrazolium chloride and 22% polyvinyl alcohol (PVA) in 0.05 M Hepes buffer; the final pH was 7.5. The study showed that in the histochemical demonstration of Gldh the use of relatively high PVA concentrations were necessary to avoid diffusion artefacts because Gldh seems to be only loosely bound to the mitochondrial matrix. The use of NaN3 as a blocker of the respiratory chain was indispensible, because without NaN3 most reduction equivalents were lost through the respiratory chain. With PMS as an exogenous electron carrier, the demonstrable Gldh activities increased significantly indicating that, in the case of Gldh, the endogenous NADH tetrazolium reductase was not sufficiently effective. Furthermore, it was shown that Gldh was affected by many small molecules (e.g. activation by sodium ions, inhibition by magnesium and calcium ions) so that minor variations of the incubation conditions may cause major differences in demonstrable activities.
 ...
PMID:Microphotometric determination of enzymes in brain sections. III. Glutamate dehydrogenase. 233 53

Squalene synthetase activity in liver microsomes from rats sacrificed at three different times of the diurnal cycle showed no significant differences. Addition of 4% cholestyramine to the food resulted in a marked increase in activity (280% of control), independent of the time of killing. 3-Hydroxy-3-methylglutaryl coenzyme A reductase and cholesterol 7 alpha-hydroxylase activity, determined as positive controls, were also found to be elevated by cholestyramine and additionally showed a diurnal variation. On the other hand, five control enzyme activities, not directly related to cholesterol metabolism, i.e. glutamate dehydrogenase, NADPH cytochrome-c reductase, beta-hexosaminidase, catalase and acyl coenzyme A oxidase, showed neither an influence of cholestyramine feeding nor a time of sacrifice dependent variation.
 ...
PMID:Regulation of squalene synthetase activity in rat liver: elevation by cholestyramine, but no diurnal variation. 294 75

The effects of different cerebro-protective agents on selected key enzymes of the energy metabolism of rat primary glial cultures and rat cerebral cortex were studied. As indicators for the capacity of the most important pathways of energy metabolism the following enzyme activities were determined: hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G-6-P-DH), malate dehydrogenase (MDH), glutamate dehydrogenase (GDH), and cytochrome-c-reductase (CCR). After a one week growth period, rat glial cultures were incubated for 3 or 4 weeks with the substances to be tested. Bencyclane (5 X 10(-5) mol/l) increased the activities of HK, G-6-P-DH, and LDH, whereas PFK and CCR were reduced. Pyritinol (10(-4) mol/l) led to a higher G-6-P-DH activity, simultaneously lowering the values for PFK, CCR, PK, LDH, and MDH. Under the influence of an extract of the leaves of Ginkgo bilobae (EGB; 100 mg/l) PFK, LDH, and MDH activities were reduced. All these alterations in enzyme activities went along with simultaneous reductions in protein content, therefore not allowing to exclude toxic effects with regard to the doses used. Moreover, direct interference with the analytical procedure was demonstrable for bencyclane and EGB. Piracetam (10(-3) mol/l), flunarizine (10(-6) mol/l), dihydroergocristine (5 X 10(-6) mol/l), and nicergoline (5 X 10(-6) mol/l) failed to induce any alteration in the employed doses. The most striking effects were obtained with meclofenoxate which was tested at 10(-3) and 10(-4) mol/l. The higher dose caused an elevation of HK, PFK, CCR, G-6-P-DH, GDH and MDH activities, while slightly reducing PK. With the lower dose of meclofenoxate CCR and G-6-P-DH activities were increased. Short-term incubation of the cultures with 10(-3) mol/l meclofenoxate for 24 hr led to an increase in LDH, G-6-P-DH, and GDH activities. Chronic incubation with meclofenoxate (10(-3) mol/l) followed by 48 hr deprivation of the drug resulted in elevated HK, PFK, CCR, G-6-P-DH, GDH, and MDH activities. These changes were accompanied by alterations in related metabolite levels. These include elevations in the concentration of creatine phosphate and fructose-1,6-bisphosphate, whereas glucose-6-phosphate levels were reduced. After one week of meclofenoxate deprivation the activities of CCR and G-6-P-DH were still elevated. The metabolites of meclofenoxate dimethylaminoethanol (DMAE; 10(-3) mol/l) and p-chlorophenoxyacetic acid (10(-3) mol/l) were also investigated.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Effects of cerebro-protective agents on enzyme activities of rat primary glial cultures and rat cerebral cortex. 294 86

The reductase enzymes in Nitrosomonas and Nitrobacter were studied under anaerobic conditions when the oxidase enzymes were inactive. The most effective electron-donor systems for nitrate reductase in Nitrobacter were reduced benzyl viologen alone, phenazine methosulphate with either NADH or NADPH, and FMN or FAD with NADH. Nitrite and hydroxylamine reductases were found in both nitrifying bacteria, and optimum activity for each enzyme was obtained with NADH or NADPH with either FMN or FAD. The product of both these enzymes was identified as ammonia. In extracts of Nitrosomonas the ammonia was further utilized by an NADPH-specific glutamate dehydrogenase. (15)N-labelled nitrite, hydroxylamine and ammonia were rapidly incorporated into cell protein by Nitrosomonas, and Nitrobacter in addition incorporated [(15)N]nitrate. Relatively gentle methods of cell disruption were compared with ultrasonic treatment, to enable a more exact study to be undertaken of the intracellular distribution of the oxidase and reductase enzymes. The functional relationship of these opposing enzyme systems in the nitrifying bacteria is considered.
 ...
PMID:Properties of some reductase enzymes in the nitrifying bacteria and their relationship to the oxidase systems. 438 32


1 2 3 4 Next >>