Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study attempted to determine whether the quantity and the quality of protein intake could influence the activity of some enzymes involved in carbohydrate metabolism. Thus, adult rats were fed for 23 days a diet containing different levels (10 to 70%) and qualities (casein, wheat gluten, and egg yolk) of protein. Variations in liver enzyme activities of pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME), glucose-6-phosphatase (G6Pase), and phosphoenolpyruvate carboxykinase (PEPCK) were studied. Also the changes in enzyme activities were compared with changes in food intake and body weight gain. Increasing the protein level produced a progressive fall in the activities of ME and PK. The decrease in PK activity was greater when the biological value of the dietary proteins was higher (P less than 0.05). On the other hand, the activities of G6PDH and PEPCK increased as the protein level increased. The activity of G6Pase was unchanged. The relationship between the two opposing enzyme activities PK and PEPCK, in relation to protein intake, shows that for each protein studied, the equilibrium between glycolysis and gluconeogenesis was obtained at different protein intakes (1.5, 1.9, and 2.2 g of protein/day/100 g of body weight, respectively, for egg yolk, casein, and wheat gluten) regardless of daily consumption of energy as carbohydrate, which are similar (8 to 9 kcal/day/100 g of body weight). This equilibrium also corresponded to the maximum weight gain (5 g) of the experimental animals. In conclusion, the experimental method used permits a simultaneous assessment of the protein and carbohydrate requirements ensuring the best weight gain in young adult rats.
J Nutr 1975 Dec
PMID:Effects of quantity and quality of dietary protein and variation in certain enzyme activities on glucose metabolism in the rat. 17 17

Hepatic carbohydrate metabolism in genetically diabetic mice (db/db) and their normal littermates has been studied. In db/db mice, body water was below normal and declined with age. The liver of db/db mice was abnormally large in relation to the metabolic mass of the body at all ages studied. In db/db mice, hepatic glycogenolysis, glycogen synthesis, glycogen synthetase, and phosphorylase were markedly increased. Gluconeogenesis from alanine or lactate in perfused livers of db/db mice was greater than normal per 100 g body water. Activities of fructose-1, 6-biophosphatase, glucose-6-phosphatase, glucokinase + hexokinase, and pyruvate kinase were elevated in livers of db/db mice. Diabetic mouse livers perfused with lactate showed a markedly reduced concentration of P-enolpyruvate and clear "forward crossover" between fructose-1, 6-P2 and fructose-6-P. In vivo glucose clearance, measured with [3-3H]glucose, in db/db mice was 170% that of normal mice. Data presented indicate that in livers of db/db mice: 1) glucose production is elevated prior to hyperglycemia, 2) glycogen turns over more rapidly, and 3) glycolytic and gluconeogenic enzymes are elevated paradoxically. These abnormalities are discussed from the viewpoint of their etiology.
Am J Physiol 1975 Dec
PMID:Hepatic metabolism of genetically diabetic (db/db) mice. I. Carbohydrate metabolism. 17 48

Since acrolein can penetrate more quickly and deeply into tissue blocks than glutaraldehyde, the possibility of the use of this aldehyde as a prefixative in enzyme cytochemistry was reinvestigated. At low concentrations, acrolein preserves the activities of the enzymes investigated, including those of glucose-6-phosphatase, which is known as one of the most vulnerable to aldehyde fixation; thus, acrolein is usable in enzyme ultracytochemistry. Enzyme activities are also preserved in tissues fixed with acrolein and glutaraldehyde combined. The rapid penetration of acrolein enables fixation in larger tissue blocks and provides greater freedom in specimen selection, especially important advantages when encountering heterogeneous materials as in pathology.
J Histochem Cytochem 1976 Dec
PMID:Acrolein as a fixative for enzyme cytochemistry. 18 91

Six young adult male rhesus monkeys were given diethylnitrosamine ip for 3-5 years. Liver biospies were done monthly. After 6 months, biopsy specimens showed individual hepatocytes and small foci of hepatocytes that were intensely positive for glycogen. During the second and later years, larger foci of such cells developed. In sections stained with hematoxylin and eosin, the glycogen-containing hepatocytes generally appeared unusually clear. Some hepatocytes, however, had eosinophilic or basophilic cytoplasm. Nuclear enlargement and atypic developed, particularly outside the foci. The hepatocytes within most foci were uniform in their histochemical features: glycogen was elevated, glucose-6-phosphatase was decreased, and ATPase activity was present not only along the bile canalicular surface but also along the enire cell membrane. After 3-5 years, neoplastic nodules and hepatocarcinomas developed in 5 of 6 animals. Two nodules and particularly the heptocarcinomas differed from the foci in one of more histochemical parameters. The findings suggested that the glycogen-containing, histochemically altered cells of the foci in one or more histochemical parameters. The findings suggested that the glycogen-containing, histochemically altered cells of the foci may be the first step in the development of neoplasia; further steps toward malignancy appeared to be frequently associated with additional alterations, such as loss of sinusoidal ATPase and re-formation of glucose-6-phosphatase.
J Natl Cancer Inst 1976 Dec
PMID:Sequential hepatic histologic and histochemical changes produced by diethylnitrosamine in the rhesus monkey. 18 98

Noradrenaline-storing granules, a mitochondrial fraction and a microsomal fraction of bovine splenic nerve trunks were prepared by differential centrifugation. These particulate fractions were characterized by their noradrenaline content, succinate dehydrogenase and glucose-6-phosphatase activity. In the presence of ATP-Mg2+ all three fractions accumulated 45Ca2+ during incubation with 0.1 mM 45 CaCl2, buffered with potassium phosphate or glycylglycine (pH 7.5; 28 degrees C). The accumulated 45 Ca2+ was not removable by EGTA, and the uptake was absent at 0 degrees C or after destruction of the particles by sonication. The behaviour of the 45 Ca2+ -uptake into all three fractions against varying ATP-concentrations, metabolic inhibitors (pentachlorophenol, desaspidine, 2,4-dinitrophenol, N-ethylmaleimide, p-chloromercuribenzoate, sodium azide, amobarbital) and drugs (phenoxybenzamine, verapamil, prenylamine, reserpine, bretylium, phentolamine) was studied. Under nearly all conditions there were differences between the 45 Ca2+ -uptake into mitochondria and that into microsomes, which suggests two distinct uptake processes. The 45 Ca2+ -uptake into the granule fraction behaved intermediate between the two other fractions under many conditions, but not under all. Therefore, it is not possible to explain the 45 Ca2+ -uptake into the granule fraction as being due to contamination with mitochondria and microsomes; an inherent ATP-Mg2+ -dependent 45Ca2+ -uptake into the nerve granules must be postulated, which is not directly coupled with the noradrenaline transport into these particles. A particulate fraction (14000-100000 g), containing noradrenaline granules, was prepared from the vas deferens of the rat. Incubation with 5 X 10(-6) M (-)-noradrenaline and 0.1 mM 45Ca2+ showed that the particles of this fraction take up noradrenaline and 45Ca2+. The uptake of both was dependent on ATP-Mg2+. The ATP-Mg2+ -dependent uptake of both noradrenaline and 45Ca2+ was substantially reduced in the corresponding tissue fraction prepared from denervated vasa deferentia.
Naunyn Schmiedebergs Arch Pharmacol 1976 Dec
PMID:Ca2+ -uptake into noradrenaline-storing granules of bovine splenic nerves. 18 27

The activity of hexokinase, glucose-6-phosphatase and glucose-6-phosphoric dehydrogenase was studied in the liver of rats after one hour, one and five days after a single oral administration of organic phosphorus insecticide valekson. It was determined that administration of the preparation led to an increase of activity in the homogenate and solubilization of glucose-6-phosphatase, activation of glucose-6-phosphoric dehydrogenase and inhibition of hexokinase. The changes were maximum one hour after the administration of the compound. The results show that a decrease of the intensity of glucose-6-phosphate formation and metabolism is one of the pathogenetic factors in the development of valekson-induced intoxication.
Biull Eksp Biol Med 1977 Dec
PMID:[Activity of glucose-6-phosphate metabolism enzymes in the livers of rats with experimental valekson poisoning]. 20 53

Microsomal glucokinase is solubilized by incubation in the presence of several metabolites. After solubilization of the enzymes, the membranes present free sites for specific binding of glucokinase, therefore, they can be purified by affinity chromatography on Sepharose--ATP-glucokinase. This method yields membranous vesicles which contain, in addition to glucokinase, uridylyl-transferase, phosphoglucomutase, sialyl-transferase and adenylate cyclase. Galactosyl-transferase, glucose-6-phosphatase and NADPH cytochrome c reductase are absent. It appears that functionally related enzyme from UDP-glucose biosynthesis are aggregated onto specific patches of the membrane, most likely from Golgi apparatus.
FEBS Lett 1978 Dec 01
PMID:[Isolation by affinity chromatography of specialized membrane fractions from cat liver microsomes]. 21 51

In order to obtain more precise information on an eventual presence of extra-membranous lipids in the interior of the nucleus, the effects of Triton X-100 on the lipid content and ultrastructure of isolated rat liver nuclei was investigated. Enzyme markers (a.o. glucose-6-phosphatase) were used to control impurities of the nuclear fractions biochemically along with transmission electron microscopy and qualitative and quantitative light microscopy to check the condition of the nuclei obtained. Treatment of the nuclear fraction with increasing concentrations of Triton X-100 resulted in a decrease of the phospholipid content down to 25% at a Triton X-100/protein ratio of 0.4. A further decrease to 8% was measured at a ratio of 1.5. Electron microscopy of nuclei of the latter group showed nuclei containing outer membrane fragments in 2.5% of their surfaces. The composition of lipids extracted from a nuclear fraction appeared to be markedly changed after treatment with Triton X-100 with an increase of the percentage of neutral lipids and the phospholipids diphosphatidyl-glycerol and spingomyelin. From the chemical and morphological data obtained, the conclusion was drawn that a substantial part of the lipids remaining in the isolated nuclei after treatment with Triton X-100 is localized in both membranes of the nuclear envelope. It cannot however, be excluded that a small portion would be present in the interior of the nuclei.
Cytobiologie 1978 Dec
PMID:The influence of Triton X-100 on the nuclear envelope of the isolated liver cell nuclei. 21 70

Hyperinsulinemia was produced in fetal rhesus monkeys for 21 days in the last third of gestation by subcutaneous pork insulin injected at 19 U a day. Plasma insulin concentrations in treated fetuses (N = 4) were 3525 microU/ml. There was no difference in paired pre- and post-treatment fetal plasma glucose concentration. Activity of the hepatic enzymes that promote glucose utilization (glucokinase and hexokinase) and glycolysis (phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase) was unaffected. Similarly, glycogen metabolism enzymes (active and inactive synthase and phosphorylase) were unaltered. Two gluconeogenic enzymes (PEPCK and glucose-6-phosphatase) were diminished in the treated group compared with controls. Fetal hyperinsulinemia enhanced lipogenic and NADPH-producing enzyme activities, as evidenced by a twofold increase in fatty acid synthase and in citrate cleavage enzyme activity. Malic enzyme was absent. Hyperinsulinemia with euglycemia (1) increases the activity of enzymes that participate in lipogenesis, (2) decreases some of those controlling gluconeogenesis, and (3) has no effect on the enzymes of glycolysis.
Diabetes 1979 Dec
PMID:Chronic hyperinsulinemia in the fetal rhesus monkey: effects on hepatic enzymes active in lipogenesis and carbohydrate metabolism. 22 50

Intrauterine growth retardation was induced in rats by ligation of the artery of one of both uterine horns. Activities of pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1,6-diphosphatase and glucose-6-phosphatase in liver were measured at 0, 1, 3 and 6 h after delivery in newborn rats from normal and sham-operated litters, and from ligated and contralateral uterine horns. Lower activities of fructose-1,6-diphosphatase were found in small-for-gestational-age animals in comparison with animals from contralateral horns. When small-for-gestational-age animals were compared with animals from sham litters (which could be regarded as more satisfactory controls), the activities of two other gluconeogenic enzymes (pyruvate carboxylase and glucose-6-phosphatase) appeared to be lower as well. It is concluded that a delay in the development of these gluconeogenic enzymes could play a role in neonatal hypoglycemia in small-for-gestational-age rats.
Early Hum Dev 1979 Dec
PMID:Gluconeogenic key enzymes in normal and intrauterine growth-retarded newborn rats. 23 14


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