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

---

Query: EC:1.4.1.2 (glutamate dehydrogenase)
4,380 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1) A lysosomal protease, a new cathepsin that inactivates glucose-6-phosphate dehydrogenase [EC 1.1.1.49] and some other enzymes and differs from cathepsin B [EC 3.4.22.1] was purified about 2,200-fold from crude extracts of rat liver by cell-fractionation, freezing and thawing, acetone treatment, gel filtration, and DEAE Sephadex and CM-Sephadex column chromatographies. 2) The new cathepsin was markedly activated by the thiol-reagent, 2-mercaptoethanol and inhibited by monoiodoacetate. 3) The molecular weight of the new cathepsin was found by Sephadex G-75 column chromatography to be 22,000, which is smaller than that of cathepsin B. 4) The optimum pH of the enzyme for inactivation of glucose-6-phosphate dehydrogenase was pH 5.0--5.5. The enzyme was unstable in alkali and on heat treatment. 5) The rates of inactivation of glucose-6-phosphate dehydrogenase, apo-ornithine aminotransferase [EC 2.6.1.13], apo-tyrosine aminotransferase [EC 2.6.1.5], apo-cystathionase [EC 4.4.1.1], glucokinase [EC 2.7.1.2], glyceraldehyde-3-phosphate dehydrogenase [EC 1.2.1.12], and malate dehydrogenase [EC 1.1.1.37] by the new cathepsin were higher than those by cathepsin B. However aldolase [EC 4.1.2.13] was inactivated more rapidly by cathepsin B than by the new cathepsin. Lactate dehydrogenase [EC 1.1.1.27], glutamate dehydrogenase [EC 1.4.1.2] and alcohol dehydrogenase [EC 1.1.1.1] were not inactivated by either cathepsin. Unlike cathepsin B, the new cathepsin scarcely hydrolyzes N-substituted derivatives of arginine.
...
PMID:Purification and properties of a new cathepsin from rat liver. 3 59

Posthepatectomy coma was produced in 13 dogs and the cerebrums were biopsied for analysis of concentrations of glucose, glucose-6-phosphate, dihydroxyacetone-phosphate, phosphoenolpyruvate, pyruvate, lactate, citrate, alpha-ketogulutarate, fumarate, malate, oxaloacetate, adenosinetriphosphate, ammonia, and glutamine as well as for activities of glucokinase, phosphofructokinase, pyruvate kinase, isocitrate dehydrogenase, glutamate dehydrogenase, malate dehydrogenase, and malic enzyme. There were no differences from normal in the brain glycolytic substrate concentrations. Four of the Krebs cycle substrates were significantly reduced, but not differently than in dogs sedated for 24 hours. The glycolytic pathway, Krebs cycle, and related enzyme activities were not significantly altered. Cerebral adenosine triphosphate concentration was unchanged but the concentrations of ammonia and glutamine increased threefold.
...
PMID:Effect of total hepatectomy on selected cerebral substrates and enzymes of the glycolytic pathways and Krebs cycle. 17 Jun 98

Activities corresponding to the enzymes glucokinase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, malate dehydrogenase, pyridine nucleotide independent malate dehydrogenase, and glutamate dehydrogenase were found in cell free extracts from Neisseria elongata subsp. gkcolytica. Activities corresponding to 6-phosphogluconate dehydrase and 2-keto-3-deoxy-6-phosphogluconate aldolase were not found. Glucose was catabolized only vira the pentose phosphate pathway. The radiorespirometric findings suggest an extensive recycling of the triose and fructose phosphates. There was no evidence for formation of pyruvate from glucose. Glutamate was oxidized via the tricarboxylic acid cycle. Pyruvate and acetate were obviously catabolized by the glyoxylic and tricarboxylic acid cycles, as in N. elongata.
...
PMID:The catabolism of glucose, glutamate pyruvate and acetate in Neisseria elongata subsp. glycolytica. 85 8

The realtionship between growth rate and the metabolic activity of certain liver enzymes was studied using two strains of White Plymouth Rock chickens which had been selected in divergent directions for eight-week body weight. The activities of hexokinase, glucokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase, citrate synthase, glycogen synthetase, glutamate dehydrogenase and aspartate transaminase were measured at 4, 8 and 20 weeks of age. The mean percentage rate of growth of the birds selected for high eight-week body weight exceeded that of the birds selected for low eight-week body weight only during the early growth period. Thereafter, and until sexual maturity, the low-line birds grew at a faster rate, relative to body size. The mature body weight of the high-line birds exceeded that of the low-line birds by a factor of approximately 1.5. A close similarity was noted between the metabolic activity of certain liver enzymes and the growth rate (relative to body size) of the birds studied. At four and eight weeks of age, the faster-growing birds (whether high- or low-line) generally exhibited a greater capacity for glucose phosphorylation and glycolysis, but a poorer capacity for glycogen synthesis, than the slower-growing birds. At twenty weeks, growth rate and metabolic activity were similar in both strains.
...
PMID:Activity of certain liver enzymes in fast- and slow-growing lines of chickens. 118 17

Tissue culture for one or seven days of pancreatic islets isolated from 21-day old fetal rats was found to be associated with a marked increase in the oxidation of L-(U-14C) glutamine by intact islets and in the activity of both alanine-glutamate and aspartate-glutamate transaminases as well as glutamate dehydrogenase in islet homogenates. This coincided with an increase in the relative amount of mitochondrial DNA. The activities of glucose-phosphorylating enzymes (hexokinase and glucokinase), glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase were less markedly increased during the culture period than those of enzymes involved in amino acid catabolism and located, in part at least, in mitochondria. The combined data suggest that the functional maturation of fetal islets during the culture period is associated with and may be attributable to a preferential maturation of their mitochondria.
...
PMID:Maturation of fetal rat islet cells in vitro during tissue culture is associated with increased mitochondrial function. 213 6

The early stages of insulin-dependent diabetes mellitus are characterized by a selective inability to secrete insulin in response to glucose, coupled to a better response to nonnutrient secretagogues. The deficient glucose response may be a result of the autoimmune process directed toward the beta-cells. Interleukin-1 (IL-1) has been suggested to be one possible mediator of immunological damage of the beta-cells. In the present study we characterized the sensitivity of beta-cells to different secretagogues after human recombinant IL-1 beta (rIL-1 beta) exposure. Furthermore, experiments were performed to clarify the biochemical mechanisms behind the defective insulin response observed in these islets. Rat pancreatic islets were isolated and kept in tissue culture (medium RPMI-1640 plus 10% calf serum) for 5 days. The islets were subsequently exposed to 60 pM human recombinant IL-1 beta during 48 h in the same culture conditions as above and examined immediately after IL-1 exposure. The rIL-1 beta-treated islets showed a marked reduction of glucose-stimulated insulin release. Stimulation with arginine plus different glucose concentrations, and leucine plus glutamine partially counteracted the rIL-1 beta-induced reduction of insulin release. The activities of the glycolytic enzymes hexokinase, glucokinase, and glyceraldehyde 3-phosphate dehydrogenase, were similar in control and IL-1-exposed islets. Treatment with IL-1 also did not impair the activities of NADH+- and NADPH+-dependent glutamate dehydrogenase, glutamate-aspartate transaminase, glutamate-alanine transaminase, citrate synthase, and NAD+-linked isocitrate dehydrogenase. The oxidation of D-[6-14C]glucose and L-[U-14C]leucine were decreased by 50% in IL-1-treated islets. Furthermore, there was a significant decrease in the ratios of [2-14C]pyruvate oxidation/[1-14C]pyruvate decarboxylation and L-[U-14C]leucine oxidation/L-[1-14C]leucine decarboxylation, indicating that IL-1 decreases the proportion of generated acetyl-coenzyme-A residues undergoing oxidation. However, in the presence of IL-1 there was a significant increase in L-[U-14C]glutamate oxidation. These combined observations suggest that exposure to IL-1 induces a preferential decrease in glucose-mediated insulin release and mitochondrial glucose metabolism. This mitochondrial dysfunction seems to reflect an impairment in proximal steps of the Krebs cycle. It is conceivable that the IL-1-induced suppression and shift in islet metabolism can be an explanation for the beta-cell insensitivity to glucose observed in the early phases of human and experimental insulin-dependent diabetes mellitus.
...
PMID:Differential sensitivity to beta-cell secretagogues in cultured rat pancreatic islets exposed to human interleukin-1 beta. 266 6

We recently described a preferential reduction of the secretory response to nutrient secretagogues (glucose; leucine plus glutamine) in islets maintained in culture after in vitro exposure to streptozotocin (SZ). The present study is an attempt to further clarify the biochemical mechanisms behind this defective insulin response. Mouse pancreatic islets were collagenase isolated and, after 4-5 days in culture, exposed during 30 min at 37 C to 1.8 mM SZ or vehicle alone (controls). The islets were subsequently cultured for 7 days in medium RPMI 1640 plus 10% calf serum, before the enzymatic and metabolic studies were performed. The activities of the glycolytic enzymes, hexokinase, glucokinase, and glyceraldehyde 3-phosphate dehydrogenase, were similar in the control and SZ-exposed islets. The relative amount of cytosolic and mitochondria-bound hexokinase was also unaffected by SZ. However, there was a 30-40% decrease in the activity of NAD+- and NADP+-dependent glutamate dehydrogenase and glutamate-aspartate transaminase in the SZ-treated islets. This coincided with a 40% decrease in L-[U-14C]glutamine oxidation in the SZ-treated islets. The D-glucose catabolism was further examined in the presence of D-[5-3H] and D-[6-14C] glucose. There was no difference between control and SZ islets in terms of glucose utilization at either 1.7 or 16.7 mM glucose. The oxidation of D-[6-14C]glucose was nevertheless decreased by more than 50% in SZ islets incubated at 16.7 mM (but not 1.7 mM) glucose. Altogether, these converging observations suggest a perturbation of distal regulatory processes, apparently at the mitochondrial level, in the D-glucose and L-glutamine catabolism of SZ-exposed islets. Whether this reflects a primary action of SZ on the islet mitochondria, or an inhibitory effect of SZ on the synthesis of mitochondrial enzymes, as a result of nuclear DNA damage, remains to be elucidated.
...
PMID:Defective catabolism of D-glucose and L-glutamine in mouse pancreatic islets maintained in culture after streptozotocin exposure. 296 23

A major difference between the metabolism of Leishmania species amastigotes and cultured promastigotes was found in the area of CO2 fixation and phosphoenolpyruvate metabolism. Malate dehydrogenase (EC 1.1.1.37) and phosphoenolpyruvate carboxykinase (EC 4.1.1.49) were at much higher activities in amastigotes than promastigotes of both L. m. mexicana and L. donovani, whereas the reverse was true of pyruvate kinase (EC 2.7.1.40). Pyruvate carboxylase (EC 6.4.1.1) and malic enzyme (carboxylating) (EC 1.1.1.40) could not be detected in L. m. mexicana amastigotes. Promastigotes of L. m. mexicana had a high NAD-linked glutamate dehydrogenase activity in comparison to amastigotes, whereas NADP-linked glutamate dehydrogenase activity was detected only in amastigotes. Leishmania m. mexicana culture promastigotes were killed in vitro by the trivalent antimonial Triostam (LD50, 20 micrograms/ml) and the trivalent arsenical melarsen oxide (LD50, 20 micrograms/ml), but they were unaffected by Pentostam. Neither antimonial drug significantly inhibited leishmanial hexokinase (EC 2.7.1.2), phosphofructokinase (EC 2.7.1.11), pyruvate kinase, malate dehydrogenase or phosphoenolpyruvate carboxykinase, whereas melarsen oxide was a potent inhibitor of all the enzymes tested except phosphoenolpyruvate carboxykinase.
...
PMID:Leishmania mexicana: enzyme activities of amastigotes and promastigotes and their inhibition by antimonials and arsenicals. 298 38

The activities of a number of enzymes in rat liver have been measured at different times during adulthood and senescence and expressed as a percentage of maximal activity that can be attained after hormonal stimulation. Three different profiles can be detected. Type I profile shows decreasing activities during adolescence (1--3 months of age), increasing activities during adulthood (4--12 months of age) and relatively high activities thereafter. Enzymes of this group are carbamoyl-phosphate synthase and arginase; DNA content shows the same pattern. Type II profile shows decreasing activities during adolescence and relatively low activities thereafter. Enzymes of this group are tyrosine aminotransferase, glucose-6-phosphatase, and glucokinase. Type III profile shows relatively high activities during adolescence, adulthood and senescence. Enzymes of this group are ornithine transcarbamoylase, glutamate dehydrogenase and hexokinase. Some enzymes are constant with age in females, but slowly decrease in activity with age in males; decreasing levels of androgens and possibly also thyroid hormones can explain this decrease in males. Decreasing activities of carbamoyl-phosphate synthase and arginase during adolescence can be attributed to a depressant effect of gonadal hormones. The difference between relatively high and relatively low basal activities of enzymes in adult and senescent rats corresponds with their relatively long and short half-lives, respectively. This relation implicates a similar rate of synthesis of glucocorticosteroid hormone-dependent enzymes.
...
PMID:Changes in the control of enzyme clusters in the liver of adult and senescent rats. 611 95

Enzyme activities and DNA content have been measure in axolotl liver during the metamorphic period (4-8 months after spawning). Three different types of enzyme activity profiles were observed. In the type I profile (carbamoyl-phosphate synthase, arginase, ornithine transcarbamoylase, and glutamate dehydrogenase) enzyme activity is high in the youngest animals studied, and shows a minimum at 5 months followed by a maximum at 8 months of age. Thereafter activities do not change or slightly decrease. In the type II profile (tyrosine aminotransferase, glucose-6-phosphatase) enzyme activity shows a peak at 5 months of age and is low thereafter. Hexokinase, the enzyme with a type III profile, shows high activity throughout the metamorphic period. DNA content remains high throughout the metamorphic period but decreases 50% between 9 and 12 months of age, probably due to an increase in the size of the hepatocytes. No glucokinase activity was detected. High activities of cluster II enzymes represent early metamorphic events, while the rising part of cluster I is associated with late metamorphic events. The apparent molecular specific activity increases during natural development between 5 and 9 months of age, or precociously, upon thyroid hormone treatment. This change in apparent molecular specific activity is correlated to the advent of ureotelism.
...
PMID:Enzyme clusters during the metamorphic period of Ambystoma mexicanum: role of thyroid hormone. 612 71


1 2 3 4 5 6 Next >>

---