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)

A membrane vesicle fraction isolated from exponentially growing Aspergillus fumigatus strain Ag 507 cultures was obtained by mechanical disruption of intact Aspergillus cells under specific osmotic conditions followed by a pH fractionation technique. Electron micrographs of the membrane vesicles indicated unit membrane structures free from cell wall material. High glucose-6-phosphatase and low lactate dehydrogenase activities verified the relative purity of the membrane vesicle fraction. Allergic bronchopulmonary aspergillosis (ABPA) patient and normal human sera were incubated with the membrane vesicle fraction followed by colloidal gold tagged rabbit antiserum to human IgG or IgE. Electron micrographs indicated ABPA patient sera possessed specific IgG and IgE antibodies to membranous components. The detergent octyl-beta-D-glucopyranoside was used to extract membrane vesicle components (MC). The enzyme profile of MC compared with cell sap components (CS) showed differences in types of enzymes. Two-dimensional polyacrylamide gel electrophoretic analyses of MC and CS detected components shared as well as unique to each fraction. In crossed immunoelectrophoresis using both rabbit antisera raised to MC and ABPA patient sera, 5 peaks were detected, while analysis of CS using rabbit antisera raised to CS produced 20 major peaks. Immunoelectrophoresis and double immunodiffusion data supported the crossed immunoelectrophoretic data: MC differed from CS. Enzyme-linked immunosorbent assay indicated high specific IgG and IgE antibody levels to MC in ABPA patient sera. Crossed immuno-affinoelectrophoresis with concanavalin A partially characterized the MC, which consist of components which have glycoprotein elements (i.e., containing alpha-D-glucose or alpha-D-mannose).
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PMID:Biochemical and immunochemical analyses of detergent solubilized antigens from membrane vesicles of Aspergillus fumigatus. 332 2

An algorithm has been devised to facilitate the diagnostic approach to the causes of hypoglycemia. This systematic approach enables the physician to reach the final diagnosis in a logical way without subjecting the child to unnecessary and possibly hazardous investigations. The algorithm is based on the following measurements as required by each patient: concentrations of blood glucose, lactate, ketone bodies, and glucose-regulating hormones. These measurements are performed with the patient in the fasting state and after loading tests (glycerol and galactose) as needed. If indicated, an enzymatic test is performed to establish the final diagnosis. Eighteen children aged 1 month to 7 years who had persistent or recurrent hypoglycemia have been examined according to this algorithm. The correct diagnosis was arrived at in 17 patients. The diagnosis was not reached in one neonate who had glucose-6-phosphatase deficiency and initially did not have lactic acidosis; once lactic acidosis developed, his illness fitted perfectly into the algorithm.
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PMID:An algorithmic approach to diagnosis of hypoglycemia. 381 39

Uterine plasma membrane preparations were obtained by centrifugation on discontinuous sucrose gradients. The specific activity of the plasma membrane marker 5'-nucleotidase was increased 10-fold while the specific activity of glucose-6-phosphatase was increased 3-fold. Electron microscopy showed mainly closed vesicles having diameters mainly in the range of 0.1 to 0.4 micron and an absence of other recognizable organelles such as mitochondria. D-Glucose transport was inhibited by sulfhydryl reagents, phloretin, and cytochalasin B. Uptake was prevented at high osmotic pressures. The Km of glucose transport was 12.2 +/- 1.1 mM. Studies of the inhibition of [3H]cytochalasin B binding by D-glucose indicated that the value of the Kd of the cytochalasin B-transporter complex was larger than 1 microM. These data demonstrate the potential usefulness of these preparations in the study of glucose transport in rat uterus and its control by steroid hormones.
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PMID:Glucose transport by uterine plasma membranes. 403 86

An 8-month-old female, maintained on breast feeding for 6 months, experienced numerous attacks of hyperventilation when weaned to baby food and was admitted with severe lactic acidosis (20 mM) and hypoglycemia. Physical examination was negative except for hepatomegaly. Fasting (18 hr) after stabilization on a high carbohydrate diet resulted in hypoglycemia (plasma glucose 40 mg/100 ml), lactic acidosis (6-10 mM), and a rise in plasma alanine. Glucagon produced a glycemic response after 6 hr, but not after 18 hr fasting. Intravenous galactose increased plasma glucose (Delta 45 mg/100 ml) but intravenous fructose, glycerol, and alanine caused a 40-50% fall in plasma glucose and a significant rise in lactate (Delta 3-4 mM). Liver biopsy showed fatty infiltration. Liver slices incubated with galactose, lactate, fructose, alanine, or glycerol converted only galactose to glucose. Hepatic glycolytic intermediates were increased below the level of fructose-1,6-diphosphate and decreased above. Hepatic phosphorylase, glucose-6-phosphatase, amylo-1,6-glucosidase, phosphofructokinase, fructose-1-phosphate aldolase, and fructose-1,6-diphosphate aldolase levels were normal, but no fructose-1,6-diphosphatase (FDPase) activity was detected. Further studies on the liver homogenate of this patient revealed the presence of an acid-precipitable activator of FDPase. Normal plasma glucose and lactate levels were maintained on an 800 cal diet of 66% carbohydrate (sucrose and fructose excluded). 5% protein, and 20% fat. When carbohydrate was reduced to 35% and protein or fat increased to 23 and 53% respectively, lactic acidosis and hypoglycemia recurred. These studies show that a deficiency of FDPase produced infantile lactic acidosis and hypoglycemia and can be controlled by an appropriate diet.
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PMID:Hepatic fructose-1,6-diphosphatase deficiency. A cause of lactic acidosis and hypoglycemia in infancy. 434 Oct 15

The three Golgi fractions isolated from rat liver homogenates by the procedure given in the companion paper account for 6-7% of the protein of the total microsomal fraction used as starting preparation. The lightest, most homogeneous Golgi fraction (GF(1)) lacks typical "microsomal" activities, e.g., glucose-6-phosphatase, NADPH-cytochrome c-reductase, and cytochrome P-450. The heaviest, most heterogeneous fraction (GF(3)) is contaminated by endoplasmic reticulum membranes to the extent of approximately 15% of its protein. The three fractions taken together account for nearly all the UDP-galactose: N-acetyl-glucosamine galactosyltransferase of the parent microsomal fraction, and for approximately 70% of the activity of the original homogenate. Omission of the ethanol treatment of the animals reduces the recovery by half. The transferase activity is associated with the membranes of the Golgi elements, not with their content. Galactose is transferred not only to N-acetyl-glucosamine but also to an unidentified lipid-soluble component.
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PMID:Golgi fractions prepared from rat liver homogenates. II. Biochemical characterization. 435 72

1. GSD-I is described in a child with partial deficiency of hepatic glucose-6-phosphatase. 2. Growth retardation and hepatosplenomegaly were major clinical features. 3. Hyperlipidaemia, lactic acidaemia, hyperuricaemia and reduced uric acid clearance were major biochemical findings. 4. Although the glucose response to glucagon and galactose was impaired, there was a striking absence of hypoglycaemia which may be attributable to residual catalytic activity of the enzyme. 5. Preliminary studies of the crude liver enzyme showed it to have a normal pH inactivation profile and apparent Km with a reduced Vmax. 6. No evidence of increased PP-ribose-P availability in fresh liver tissue was detected. 7. Continuous glucose feeding resulted in accelerated growth without complete correction of lactic acidosis or hyperuricaemia. 8. GSD-I with partial deficiency of hepatic glucose-6-phosphatase should be considered in patients with gout or hyperuricaemia associated with hypertriglyceridaemia and lactic acidaemia even in the absence of hypoglycaemia.
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PMID:Clinical and enzymological studies in a child with type I glycogen storage disease associated with partial deficiency of hepatic glucose-6-phosphatase. 615 47

The topography of phosphatidylcholine, phosphatidylethanolamine and triacylglycerol biosynthetic enzymes within the transverse plane of rat liver microsomes was investigated using two impermeant inhibitors, mercury-dextran and dextran-maleimide. Between 70 and 98% of the activities of fatty acid : CoA ligase (EC 6.2.1.3), sn-glycerol-3-phosphate acyltransferase (EC 2.3.1.15), phosphatidic acid phosphatase (EC 3.1.3.4), diacylglycerol acyltransferase (EC 2.3.1.20), diacylglycerol cholinephosphotransferase (EC 2.7.8.2) and diacylglycerol ethanolaminephosphotransferase (EC 2.7.8.1) were inactivated by mercury-dextran. Dextran-maleimide caused 52% inactivation of the sn-glycerol-3-phosphate acyltransferase. Inactivation of each of these activities except fatty acid : CoA ligase occurred in microsomal vesicles which remained intact as evidenced by the maintenance of highly latent mannose-6-phosphatase activity (EC 3.1.3.9). These glycerolipid biosynthetic activities were not latent, indicating that substrates have free access to the active sites. Moreover, ATP, CDP-choline and CMP appeared unable to penetrate the microsome membrane. These data indicate that the active sites of thease enzymes are located on the external surface of microsomal vesicles. It is concluded that the biosynthesis of phosphatidylcholine, phosphatidylethanolamine and triacylglycerol occurs asymmetrically on the cytoplasmic surface of the endoplasmic reticulum.
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PMID:Topography of phosphatidylcholine, phosphatidylethanolamine and triacylgycerol biosynthetic enzymes in rat liver microsomes. 615 20

The effects of histone 2A and some polycations on microsomal carbamylphosphate:D-glucose phosphotransferase and glucose-6-phosphate phosphohydrolase activities (D-glucose-6-phosphate phosphohydrolase, EC 3.1.3.9), have been investigated. 1. Histone 2A and polycations activate the two enzymic activities. At a constant cation concentration, this activation increases with the number of cationic groups per molecule. 2. Activation by histone 2A is related to its fixation on microsomal membranes. This fixation varies with quantities of histones and pH. 3. The nature of the interactions between histones and microsomal membranes is shown to be electrostatic, probably between the cationic groups of histones and the anionic group of membranous lipids. 4. Kinetic analysis reveal that histone 2A increases the maximal reaction velocity but does not affect the apparent Michaelis constant values for the substrates. 5. The role played by the cationic groups of histone 2A on the microsomal glucose 6-phosphatase, is discussed.
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PMID:[Effects of basic proteins of low molecular weight on the phosphohydrolase and phosphotransferase activities of microsomal glucose-6-phosphatase in adult monkey hepatocytes (author's transl)]. 625 Jun 25

A girl presented with an important growth retardation, hepatomegaly, fasting hypoglycemia, lactic acidosis, increased serum cholesterol, triglycerides and uric acid, and increased liver glycogen (7.5%). There was no rise in blood glucose after IV galactose or fructose, but glucagon gave a delayed response. Type Ib glycogen storage disease was suggested by the low normal activity of glucose-6-phosphatase (G-6-Pase) which reached 1.8 units/g (normal, 2 to 10 units/g) and the normal activity of other glycogenolytic enzymes, measured in homogenates prepared in H2O (mean +/- S.E. in control subjects: 59% +/- 7; in type Ia GSD: 92% +/- 3). The activity of G-6-Pase measured as described above increased to 3.8 units/g of liver 1 year after PCS and 7.85 units/g of liver after 3 years. At that time, a simultaneous assay of the enzyme in a fresh, previously not frozen liver biopsy, homogenized in 0.25 M sucrose, revealed only about 29% of the activity of the same sample prepared in H2O (mean +/- S.E. in three controls: 95.8% +/- 8.9.
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PMID:Clinical and biochemical findings before and after portacaval shunt in a girl with type Ib glycogen storage disease. 625 80

The factors regulating glucose-6-phosphatase (EC 3.1.3.9) activity and substrate specificity in hepatic microsomes were studied by determining the rate-limiting reaction for the hydrolysis of glucose-6-P, and by examining the effect of detergent activation on phosphotransferase activity. Examination of the pre-steady state kinetics of glucose-6-phosphatase revealed that the steady state rate is determined by the rate of hydrolysis of the enzyme-P intermediate. Treatment of the enzyme with detergent does not alter the extent of the rapid release of glucose per mg of protein, but activates the steady state rate of catalytic turnover. Specificity of the enzyme was evaluated by comparing the effects of mannose and glucose as phosphate acceptors in the phosphotransferase reaction catalyzed by glucose-6-phosphatase. Untreated glucose-6-phosphatase discriminates against mannose as compared with glucose in that mannose and glucose bind to the enzyme-P intermediate of untreated enzyme, but mannose is not an acceptor of Pi. Mannose is an acceptor, however, after treatment of microsomes with detergent. These data cannot be explained in terms of the currently accepted "compartmentation" model for the regulation of glucose-6-phosphatase. The detergent-induced changes in kinetic properties appear to reflect alterations in the intrinsic characteristics of glucose-6-phosphatase, which could result from interaction with its membrane environment.
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PMID:The role of the membrane in the regulation of activity of microsomal glucose-6-phosphatase. 627 75


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