Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:APRD00080 (Leaf)
 21,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The transport and phosphorylation of 2-deoxy-D-[3H]galactose in rabbit renal cortical cells was studied. 1. The uptake of 2-deoxy-galactose by cortical slices is associated with an appearance of both free and phosphorylated sugar in the cells. At 1 mM external sugar the cells establish a steady-state gradient of free 2-deoxy-galactose of 3.97 +/- 0.15 (23 animals). 2. The acid-labile sugar phosphate accumulated in the tissue has been identified by a combination of paper and radio-chromatography, as well as on the basis of some of its chemical properties, as 2-deoxy-D-galactose 1-phosphate. Ice-cold trichloroacetic acid produces a decomposition of this compound. 3. Increasing external pH (6-8) brings about a decrease in the steady-state levels of both free and phosphorylated sugar in slices. On the other hand, increasing pH activates the phosphorylation of 2-deoxy-D-galactose by a crude kinase in a tissue extract. 4. Sugar phosphate accumulated in the cells is dephosphorylated by the action of a Zn2+ -activated phosphatase. 5. The efflux of 2-deoxy-D-galactose from the cells is rather slow compared with that found for D-galactose. The efflux is associated with some dephosphorylation of cellular sugar phosphate, and some loss of 2-deoxy-galactose phosphate into the wash-out medium takes place. 6. An inhibition analysis of the uptake of 2-deoxy-D-galactose by the slices indicates that the transport site is shared by D-galactose. The following points of interaction between the sugar molecule and the carrier are identified: C1-OH, C3-OH and C4-OH (both axial) and C6-OH. A (pyranose) ring structure is also essential. A close packing between the substrate and the carrier in the vicinity of C2 is indicated. 7. The data suggest that the above transport system is localized predominantly at the antiluminal (basolateral) face of the renal tubular cells. While the detailed mechanism of the actual transport step (i.e. active transport of the free sugar, or by the action of a phosphotransferase) is still unclear, the data present evidence that both galactokinase and a Zn2+ -activated phosphatase participate in the maintenance of an intracellular steady state of the transported sugar.
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PMID:Transport and phosphorylation of 2-deoxy-D-galactase in renal cortical cells. 1 Sep 99

When Dictyostelium discoideum amoebae (strain V12 M2) are spread at high density on agar containing 1 mM cyclic AMP, essentially all the cells differentiate into stalk cells after 2-3 days. We showed previously that isolated amoebae plated at low density on agar containing cyclic AMP do not differentiate, but can be induced to do so by a layer of high density helper cells from which they are separated by a thin cellophane membrane. We now show that the high density cell population releases a dialyzable factor that, in the presence of cyclic AMP, is capable of inducing isolated amoebae to differentiate into stalk cells. Sugar inhibition, sensitivity to glycosidases, and lectin affinity suggest that the differentiation-inducing activity requires the integrity of an oligosaccharide group containing sialic acid, L-fucose, and N-acetylgalactosamine. In addition, a phosphate group appears to be necessary for biological activity.
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PMID:An oligosaccharide-containing factor that induces cell differentiation in Dictyostelium discoideum. 21 95

The pyruvate kinases of Escherichia coli activated by ribose 5-phosphate (RP) has been partially purified. The active form of the enzyme has a molecular weight of about 180 000 as judged by sucrose density gradient centrifugations and Sephadex G-150 chromatography. On dissociation in the absence of sulfhydryl reagents such as dithiothreitol, the enzyme is inactivated and it has a molecular weight of about 110 000. Various substrates and effectors of the enzyme, with the exception of phosphate, do not influence the association-dissociation equilibrium of the enzyme. The enzyme, unlike pyruvate kinases from many other sources, is not activated by potassium ions. Sulfate and phosphate ions are inhibitory to the enzyme. Phosphate seems to be an allosteric inhibitor and its effect is completely antagonized by activators. The enzyme is activated in an allosteric manner by two classes of compounds, nucleoside monophosphates and sugar phosphates of the hexose monophosphate pathway. Amongst the nucleotides, guanosine 5'-phosphate and adenosine 5'-phosphate are the most effective activators. Amongst the hexose monophosphate pathway intermediates, RP is the most powerful activator, with apparent activation constants as low as 1 Mu. Sugar phosphates esterified at C-1 or both terminal positions are entirely ineffective in activation. The effectors act by changing the Michaelis constant for the substrates. Both of the substrates of the enzyme, adenosine diphosphate and phosphoenolpyruvate, yield cooperative-concentration plots in the presence of unsaturating concentrations of the fixed changing substrate. The initial velocity plots for both substrates become hyperbolic in the presence of saturating concentrations of RP.
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PMID:The control of pyruvate kinases of Escherichia coli. II. Effectors and regulatory properties of the enzyme activated by ribose 5-phosphate. 23 81

Nascent calcium phosphate promotes the agglutination and fusion of human erythrocyte ghosts. Membrane phospholipids of erythrocyte ghosts treated with Ca2+ and phosphate ions become exposed to attack by phospholipase C (phosphatidylcholine cholinephosphohydrolase, EC 3.1.4.3) (Bacillus cereus). Freeze-fracture pictures of fused erythrocyte ghosts show the presence of regions deficient in intramemebrane particles in the protoplasmic face which we believe to be regions of fusion. Discontinuous regions of the protoplasmic and exoplasmic faces are observed, which are apparently intermediate stages in the process of fusion. TH-in-section electron micrographs reveal deposits of calcium phosphate in areas of contact and fusion of ghosts. Ca2+ in the presence of N-[tris(hydroxymethyl)methyl]glycine (Tricine) buffer causes the formation of blebs in the membrane but does not cause changes in the intramembrane particle pattern or induce fusion. It is suggested that nascent calcium phosphate acts by forming protein-free regions of phospholipid bilayer which can fuse readily.
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PMID:Membrane ultrastructural changes during calcium phosphate-induced fusion of human erythrocyte ghosts. 32 83

Freeze fracturing electron microscopy of Escherichia coli K12 cells showed that the outer fracture face of the outer membrane is densily occupied with particles. On the inner fracture face of the outer membrane, pits are visible, which are probably complementary to the particles at opposite fracture face. This observation suggests that the particles are micelle-like. In some mutants which lack one or more major outer membrane proteins the density of particles is reduced. The loss of protein d appeared to a prerequisite for this phenomenon. However, mutants which lack all glucose and heptose-bound phosphate in their lipopolysaccharide also have a reduction in particle density whereas, the amount of protein d is normal. Moreover, loss of lipopolysaccharide by EDTA treatment also caused a reduction in the density of particles. From these results it is hypothesized that the particles consist of lipopolysaccharide aggregates stabilized by divalent cations and probably complexed with protein and/or phospholipid.
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PMID:Architecture of the outer membrane of Escherichia coli K12. II. Freeze fracture morphology of wild type and mutant strains. 40 48

Enzyme IIlac, the membrane-bound component of the lactose phosphotransferase system of Staphylococcus aureus, catalyzes the phosphorylation-transport reaction below: (see article). (The sugar can be lactose or one of its analogs.) The effects of the non-ionic detergents Triton X-100, Brij 35, and Tween 40 on the activity of Enzyme IIlac were studied. Especially striking effects were observed using Triton X-100, a detergent previously used to solubilize and isolate this enzyme. A systematic study of Triton effects over a range of concentrations and temperatures demonstrated three aspects of Triton-membrane interaction. At 0.1% Triton and 25 degrees C Enzyme IIlac is activated, but remains particulate. At 0.5% Triton and 0.5% Triton and 37 degrees C, it is rapidly and irreversibly inactivated. Sugar substrates and inhibitory sugar analogs protect Enzyme IIlac against inactivation; the effect is specific for beta-galactosides. The other substrate of Enzyme IIlac, phospho-Factor IIIlac, does not affect Triton inactivation, and the product analog galactose 6-phosphate slightly enhances the inactivation rate.
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PMID:Irreversibel inactivation of the membrane-bound enzyme IIlac of the lactose phosphotransferase system of Staphylococcus aureus by triton X-100 and protection by substrates. 83 39

Highly purified sympathetic nerve vesicles isolated from bovine splenic nerves were treated by hypo-osmotic shocks, freeze-thawing or incubation in the absence or presence of ATP and MgCl. The vesicle preparations were then studied morphologically by electron microscopy and their content of noradrenaline (NA), and soluble proteins analyzed biochemically with special regard to dopamine beta-hydroxylase (DBH). Hypo-osmotic shocks released about 25 per cent of the NA and protein content and about 8 per cent of the DBH activity. This treatment induced swelling of the vesicles but their membranes remained unruptured and they still contained dense cores. Freeze-thawing released about 35 per cent of the NA, 25 per cent of the proteins and 11 per cent of the DBH. After the latter treatment some matrix material still remained in most vesicles but many were less stainable than the intact vesicles in cold control preparations. During incubation at 30 degrees C in an isotonic sucrose-phosphate medium for 30 min the vesicles released most of their NA and soluble DBH activity as well as much of their matrix density. After incubation at 37 degrees C for 30 min most vesicles appeared translucent. After incubation at 30 degrees C for 30 min in the presence of ATP and MgCl the vesicles lost most of their original NA content but retained their DBH activity and most of their matrix density. The results indicate that there is not always a correlation between NA content and retention of matrix density which suggests that DBH might be a component of a macro-molecular complex responsible for the staining reaction taking place in the maxtrix of NA depleted vesicles. This hypothesis is further supported by the finding of striking similarities between DBH isolated from chromaffin granules and the granular and fibrillar material surrounding the nerve vesicles after depletion.
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PMID:On the soluble phase of adrenergic nerve vesicles: correlation of matrix density and biochemical composition. 114 Oct 28

Carbamylation of the NH2-terminal residues of the beta chains on hemoglobin (alpha2beta2c) leads to a reduced but still significant binding of 2,3-diphosphoglycerate, but has no effect on the oxygen-linked binding of chloride or phosphate, both of which are thought to bind to some of the same residues as the organic phosphate. Studies by others have shown that the binding of inorganic anions is not diminished in either horse hemoglobin or in hemoglobin Little Rock, in which four of the six other binding sites (histidine residues) for organic phosphates are replaced by glutamine residues. We suggest, therefore, that lysines 82 of the beta chains, which are the remaining 2 residues in the binding crevice for the organic phosphate, and which are invariant in the known sequences of mammalian hemoglobins, may be the primary binding site for inorganic anions. The extent of inhibition of gelation by increasing ionic strength is identical for the hybrids alpha2beta2, alpha2cbeta2, and alpha2beta2c of hemoglobin S. These results indicate the NH2-terminal residues of the chains are not involved in primary electrostatic interactions during aggregation of deoxyhemoglobin S.
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PMID:The interaction of anions with hemoglobin carbamylated on specific NH2-terminal residues. 117 67

Five per cent (w/v) extracts of defatted Ambrosia elatior pollen were prepared in bicarbonate-buffered saline (Coca's extract) and Coca's extract with 50% glycerol (Gly-Coca's extract). Sterile extracts were stored in untreated glassware and glassware coated with silicone. Stock extracts were diluted in phosphate-buffered saline (PBS) and stored at 5 +/- 3 degrees C. Extracts 1:20, 1:40, and 1:400 were assayed at approximately 6-wk intervals for antigen E. Quantitative determinations were made by modified double diffusion in agarose gels using known standards of antigen E for comparison. Results from the first year of this 3-yr study show no significant reduction in 1:20 Gly-Coca's extracts and a highly significant reduction of antigen E in 1:20 Coca's extracts. Further analysis of variance indicates significant reduction in all 1:40 and 1:400 extracts. Differences in the initial extracting solvents did not significantly affect these more dilute extracts. No significant differences were observed in the untreated and silicone-coated glassware. In terms of per cent antigen E reduction, 1:20 Gly-Coca's showed negligible reduction and Coco's at 1:20 declined nearly 50% in antigen E content. Extracts stored at 1:40 retained only 40% of the original antigen E content, while diluted extracts stored at 1:400 retained only 35% of the initial antigen E after 1 yr of storage at 5 +/- 3 degrees C.
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PMID:Studies on the deterioration of antigen E in extracts of Ambrosia elatior. 124 82

A nontracer amount (0.25 mmol/kg of body weight) of 2-deoxyglucose (DG) was intravenously injected into rats, which were frozen 2 and 4 min later in liquid nitrogen. Freeze-dried samples of CNS regions and cell bodies of spinal motor neurons were prepared, and the concentrations of glucose, glucose 6-phosphate, DG, and DG 6-phosphate (DG6P) in them were microassayed after 3,000-1,500,000-fold amplification using an enzymatic amplification reaction, NADP cycling. Based on the time course of glucose, DG, and DG6P concentrations in arterial plasma and the anterior horn of the spinal cord, the Sokoloff-type rate equations for DG and DG6P concentrations were mathematically solved, and the resultant DG and DG6P concentration functions were fitted to the data points using the nonlinear least-squares fitting SALS package program. This fitting provided four rate constants for the functions and supported the theoretical basis for our calculations of glucose utilization rate (GUR) when DG was administered in nontracer amounts. The GUR was highest in the spinal motor neurons and lowest in the white matter of the cerebellum. Neuron-rich structures, such as the cerebellar molecular and granular layers and the anterior horn of the spinal cord, had higher GUR values than the white matter of the cerebellum and spinal cord.
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PMID:Microdetermination of 2-deoxyglucose and 2-deoxyglucose 6-phosphate to determine glucose utilization rates in single neurons and small CNS regions after injecting nontracer amounts of 2-deoxyglucose. 149 15


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