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)

Acute renal failure was induced in male rats by the subcutaneous injectioon of 4 mg HgC12 per kg body weight. Enzyme activities of the proximal tubule were studied histochemically at six time intervals from 15 min to 24 h. The enzyme studied were alkaline phosphatase, 5'-nucleotidase, acid phosphatase, alpha-glycerophosphate dehydrogenase (NAD-independent), malic dehydrogenase, succinic dehydrogenase, latic dehydrogenase, glucose-6-phosphate dehydrogenase and glucose-6-phosphatase. Decreases in activity were observed for alkaline phosphatase and 5'-nucleotidase after 15 min. Acid phosphatase was decreased after 30 min. These three enzymes returned to control levels after 3 h, but malic dehydrogenase and alpha-glycerophosphate dehydrogenase were decreased at this time interval. Succinic dehydrogenase was first decreased after 6 h. The earliest morphological changes detectable by light microscopy were observed in pars recta tubules in the medullary rays after 6 h, a time when all enzymes studied showed widespread decreased activity throughout the proximal tubule. After 24 h, the pars convoluta appeared morphologically normal but the pars recta was necrotic and exhibited calcification, whereas enzyme activity was decreased (absent in some cases) in both pars convoluta and pars recta. These results support the hypothesis that Hg++, when given in a sublethal dose, is associated with early histochemical changes in the brush border of the proximal tubule, which may be related to early changes in sodium reabsorption and to the subsequent development of acute renal failure. The observation that changes in plasma membrane-associated enzymes occur early and prior to alterations in enzymes of mitochondria and the endoplasmic reticulum suggests that Hg++ interacts initially with the plasma membrane.
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PMID:Studies on the pathophysiology of acute renal failure. II. A histochemical study of the proximal tubule of the rat following administration of mercuric chloride. 18 27

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.
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PMID:Ca2+ -uptake into noradrenaline-storing granules of bovine splenic nerves. 18 27

Xenopus laevis (Daudin) adult specimens were submitted to hypophysectomy. Although the operation resulted subtotal, it served the purpose of removing the prolactin-producing cells, whereby the involvement of endogenous prolactin in osmoregulation phenomena was excluded. In the operated animals treated with ovine prolactin the following metabolic parameters, which are closely dependent upon interrenal activity, were estimated: 1) intestine alkaline phosphomonoesterase activity (E.C. 3.1.3.1); 2) liver glycogen level; 3) glucose-6-phosphatase (E.C. 3.1.3.9.) and phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32.) in the liver; 4) blood glucose level; 5) blood ammonia and urea levels; 6) carbamoylphosphate synthetase activity in the liver (E.C. 2.7.2.a); 7) muscle sodium and potassium levels. The above metabolic parameters were found to be pressed by subtotal hypophysectomy and after subsequent prolactin treatment showed the tendency to go back to values similar to those of control animals.
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PMID:Biochemical data on subtotally hypophysectomized Xenopus laevis (Daudin) adult specimens treated or not with prolactin. 21 25

A procedure was developed for the isolation of cardiac sarcolemmal vesicles. These vesicles are enriched about ten-fold (with respect to the tissue homogenate) in K+-stimulated p-nitrophenylphosphatase, (Na+ + K+)-ATPase, 5'-nucleotidase activities and sialic acid content, all of which are believed to be components of the sarcolemma. The sarcolemma of tissue culture cardiac cells were radioiodinated and the distribution of this radioiodine paralleled the distribution of the other membrane markers above. There was very little contamination of the sarcolemmal fraction by sarcoplasmic reticulum (as judged by Ca2+-ATPase and glucose-6-phosphatase activities) or inner mitochondrial membranes (as judged by succinate dehydrogenase activity). There may, however, be some contamination by outer mitochondrial membranes (as judged by monoamine oxidase and rotenone-insensitive NADH cytochrome c reductase activities) which have rarely been monitored in cardiac sarcolemmal preparations. The purity of this preparation is good when compared with other cardiac sarcolemmal preparations. This preparation should be very useful in studying the roles of the cardiac sarcolemma (e.g. in excitation contraction coupling and Ca2+ binding).
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PMID:Isolation and characterization of cardiac sarcolemma. 22 23

Kinetic studies indicate that glucose-6-phosphatase is a multifunctional enzyme. a) Phosphohydrolase activities. The mannose-6-phosphatase activity is low (Km = 8 mM, VM = 90 nmoles. min-1mg-1). The enzyme shows a strong affinity for glucose-6-phosphate (Km = 2.5 mM, VM = 220 nmoles.min-1mg-1). beta-glycerophosphate (K1 = 30 mM), D-glucose (Ki = 120 mM) are mixed type inhibitors; pyrophosphate (Ki = 2 mM) is a non competitive one. b) Phosphotransferase activities. Di and triphosphate adenylic nucleosides or phosphoenol pyruvate are not substrates. Carbamylphosphate serves as a phosphoryl donor with D-glucose as acceptor. The phosphate transfer is consisstent with a random mechanism in which the binding of one substrate increases the enzymes affinity for the second substrate. Apparent Km values for carbamyl-phosphate range from 5.2 mM (D-glucose concentration leads to infinity) to 8 mM (D-glucose concentration leads to 0). The corresponding apparent Km values for D-glucose are 59 mM (carbamyl-phosphate concentration leads to infinity) to 119 mM (carbamyl-phosphate concentration leads to 0). Maximal reaction velocity with infinite levels of both substrates is 270 nmoles.min-1.mg-1. Pyrophosphate is a poor phosphoryl donnor (Km = 55 mM with D-glucose concentration 250 mM). In addition we do not find any latency; detergents, namely sodium deoxycholate, Triton X 100 do not affect or inhibit glucose-6-phosphatase activity.
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PMID:[Monkey liver microsomal glucose-6-phosphatase]. 23 60

By means of a preparation technique based on the discontinuous sucrose density gradient, subcellular fractions were isolated from guinea pig intestinal smooth muscle cells. A fraction which distributed to a 33% sucrose layer showed relatively high activities of 5'-nucleotidase, Na+ . K+-ATPase and ouabain sensitive Na+ . K+-ATPase. The fraction had a low NaN3 sensitive Mg2+-ATPase activity. On the other hand, the high activity of glucose-6-phosphatase showed a broad distribution. Though the sucrose density gradient proceeded over a series of the fine layers, cross-contamination of microsome into the 33% sucrose fraction was not reduced. To reduce microsomal cross-contamination, another procedure was employed. The homogenization time of 77000 xg sediment to be layered on the top of the sucrose density gradients was prolonged. This procedure did not change the distribution of K+ activated p-nitrophenylphosphatase, K+ activated ouabain sensitive p-nitrophenylphosphatase and ouabain sensitive Na+ . K+-ATPase activities. The peak of NADH cytochrome c reductase activity was shifted to a 38% sucrose fraction from a 33% sucrose fraction and the activity of this marker enzyme in the 33% sucrose fraction decreased to 60% of that of the prior procedure.
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PMID:[Examination of plasma membrane-enriched fraction from guinea pig intestinal smooth muscle by means of some marker enzymes (author's transl)]. 23 74

To determine the hepatic and intestinal toxicity of sodium cyanate, this compound was administered to rats by orogastric tube (PO) or intraperitoneal injection (IP). At low dosage (50 mg. per kilogram per day PO for 8 weeks), the animals showed no clinical effects other than mild lethargy. They had normal intestinal absorption studies, but demonstrated decreased liver G6PD activity and a slight increase in hepatic glycogen. At higher dose levels (200 mg. per kilogram per day PO for 10 days, 400 mg. per kilogram per day PO for 3 days, and 100 mg. per kilogram per day IP for 10 days), the animals became very lethargic and developed hind-limb paralysis; many animals died during the period of dosing. The severity and rate of onset of symptoms increased proportionally with the dose level. Liver sections from rats receiving these higher doses showed striking increases in glycogen deposition. Activities of hepatic enzymes involved in glycogen synthesis and degradation were measured in rats receiving 200 mg. per kilogram per day PO or 100 mg. per kilogram per day IP. Significant decreases were noted in the activities of glucose-6-phosphatase and G6PD in PO-dosed rats. The activities of phosphorylase, UDPG-pyrophosphorylase, glycogen synthetase, phosphoglucomutase, and debrancher did not differ from control rats. In IP-dosed rats, significant decreases were observed in the activities of glucose-6-phosphatase, G6PD, phosphorylase, and UDPG-pyrophosphorylase, but not in the other glycogen-related enzymes. Our data suggest that sodium cyanate affects several enzymes of hepatic glycogen metabolism but that the enzymes vary in their susceptibility (glucose-6-phosphatase and G6PD greater than phosphorylase and UDPG pyrophosphorylase.
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PMID:In vivo hepatic and intestinal toxicity of sodium cyanate in rats: cyanate-induced alterations in hepatic glycogen metabolism. 23 70

Enveloped and unenveloped forms of herpes simplex virus (HSV) occurring in infected rabbit lung (ZP line) cells were purified by differential and discontinuous Ficoll density gradient centrifugation. Then the viral particles were separated in a sucrose-D2O density gradient. In the course of the procedures, both virus preparations were freed of Mg2+-dependent Na+ plus K+-stimulated adenosine triphosphatase (ATPase), 5'-nucleotidase, and glucose-6-phosphatase activities. However, Mg2+ -activated ATPase was shown to be firmly associated with purified virions. The recovery of infectious virus was 50-60 percent. The specific infectivities (TCID50/mg protein) of the purified enveloped and unenveloped viral particles were 1-2 times 10(10) and 2-5 times 10(6), respectively. The infectivity of the unenveloped viral particles was discussed.
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PMID:Purification and separation of enveloped and unenveloped herpes simplex virus particles. 24 Dec 23

When lead acetate was administered intraperitoneally to young rats at a dose of 20 mg/kg (five times a week for 6 weeks), their growth rate was retarded when compared with controls injected with sodium acetate. Only a small amount of the heavy metal reached the circulation and exerted limited effects on typical target organs. However, large, electron-dense inclusion bodies were found in the abdominal cavity. The in vivo intestinal absorption of glucose was reduced. When perfused at 40 mM concentration, the experimental animals had a mean absorption rate of 152.1 nmol/min . cm vs. 230.6 in the controls (p less than 0.01). Also, sodium and potassium transport was reduced. No effects were observed on amino acid transport and (Na+-K+)-ATPase. Mg++-ATPase, glucose-6-phosphatase, fructose-1, 6-diphosphatase, pyruvate kinase, succinic dehydrogenase, and tryptophan hydroxylase in the small intestinal mucosa and the kidney were unaltered. Renal alkaline phosphatase was decreased. These studies confirm the greater susceptibility of some active transport mechanisms of the small intestinal mucosa to lead toxicity, compared to those of the kidney.
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PMID:Alterations of intestinal and renal functions in rats after intraperitoneal injections of lead acetate. 46 71

When chickens are infected with the coccidial parasite Eimeria necatrix, the plasma membrane of intestinal cells harbouring second-generation schizonts becomes refractory to mechanical shearing, hypotonic shock and ultrasonication. Plasma membrane from these infected cells was isolated to high purity as judged by enriched levels of ouabain-sensitive (Na+ + K+)-stimulated Mg2-dependent ATPase activity and sialic acid content, the lack of detectable cytochrome oxidase and glucose-6-phosphatase activities and electron microscopic analysis of the final preparation. Wide-angle X-ray diffraction patterns recorded from the isolated membranes revealed that during the later stages of parasite maturation the host cell plasma membrane acquires increasing proportions of gel-phase lipid. By contrast, purified membrane from isolated parasites is in a liquid-crystalline state. The transition temperature of host cell plasmalemma at 100 h postinfection is 61 degrees C, about 20 degrees C above physiological temperature. By contrast, liposomes of plasma membranes from infected cells undergo a thermal transition at about 28 degrees C. The accumulation of gel-phase lipid in the host cell plasma membrane is not attributable either to an increase in the constituent ratio of saturated to unsaturated fatty acids or to a significant change in the cholesterol to phospholipid ratio. During the late stages of infection, the cells become stainable with trypan blue which suggests that the acquisition of crystalline phase lipid disrupts the permeability of the host cell plasmalemma.
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PMID:Induction of gel-phase lipid in plasma membrane of chick intestinal cells after coccidial infection. 48 63


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