Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is generally assumed that phosphate (Pi) effluxes from proximal tubule cells by passive diffusion across the basolateral (BL) membrane. We explored the mechanism of BL Pi efflux in proximal tubule-like OK cells grown on permeable filters and then loaded with 32P. BL efflux of 32P was significantly stimulated (P < 0.05) by exposing the BL side of the monolayer to 12.5 mM Pi, to 10 mM citrate, or by acid-loading the cells, and was inhibited by exposure to 0.05 mM Pi or 25 mM HCO3; by contrast, BL exposure to high (8.4) pH, 40 mM K+, 140 mM Na gluconate (replacing NaCl), 10 mM lactate, 10 mM succinate, or 10 mM glutamate did not affect BL 32P efflux. These data are consistent with BL Pi efflux from proximal tubule-like cells occurring, in part, via an electro-neutral sodium-sensitive anion transporter capable of exchanging two moles of intracellular acidic H2PO4- for each mole of extracellular basic HPO4= or for citrate.
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PMID:Basolateral phosphate transport in renal proximal-tubule-like OK cells. 1219 5

Copoly (benzyl glutamate-hydroxy ethyl glutamine) were prepared by partially aminolysis of poly benzyl glutamate with hydroxyl ethylamine at 60 degrees C for predeternined period. As aminolysis was proceeding, the content of hydroxy ethyl glutamine in copolymer increased and the yield of aminolysis decreased. When aminolysis time reached 16.5 hours, a copolymer with 0.357 mole fraction of hydroxy ethyl glutamine was obtained. After 16.5 hours a soluble yellow viscous product of reaction was obtained. The aminolysized specimens displayed more swelling degree in water, that is, more hydrophilits. The meassurement of solid-liquid contact angles showed that an increase in critical surface tention with content of hydroxy ethyl glutamine in copolymer was observed. Likewise a obvious increase in polar component and a slight decrease in dispersive of surface free energy, thus an increase in total surface free energy with content of hydroxy ethyl glutamine was found. The platelet adhesion and deformation test indicated that less platelets were adhered to surfaces of all aminolysized specimens than that of both poly benzyl glutamate and polydimethylsilicone. The least adhered platelets on surface of copolymer with 0.133 mole fraction of content of hydroxy ethyl glutamine were observed. The partiall aminolysis of poly benzyl glutamate films is an effective method to improve its hydrophility and antithrombogenicity.
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PMID:[Study on adhesion of platelets to surface of copoly(benzyl glutamate-hydroxy ethyl glutamine)]. 1256 50

An experimental method for metabolic control analysis (MCA) was applied to the investigation of a metabolic network of glutamate production by Corynebacterium glutamicum. A metabolic reaction (MR) model was constructed and used for flux distribution analysis (MFA). The flux distribution at a key branch point, 2-oxoglutarate, was investigated in detail. Activities of isocitrate dehydrogenase (ICDH), glutamate dehydrogenase (GDH), and 2-oxoglutarate dehydrogenase complex (ODHC) around this the branch point were changed, using two genetically engineered strains (one with enhanced ICDH activity and the other with enhanced GDH activity) and by controlling environmental conditions (i.e. biotin-deficient conditions). The mole flux distribution was determined by an MR model, and the effects of the changes in the enzyme activities on the mole flux distribution were compared. Even though both GDH and ICDH activities were enhanced, the mole flux distribution was not significantly changed. When the ODHC activity was attenuated, the flux through ODHC decreased, and glutamate production was markedly increased. The flux control coefficients of the above three enzymes for glutamate production were determined based on changes in enzyme activities and the mole flux distributions. It was found that the factor with greatest impact on glutamate production in the metabolic network was obtained by attenuation of ODHC activity.
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PMID:Effects of the changes in enzyme activities on metabolic flux redistribution around the 2-oxoglutarate branch in glutamate production by Corynebacterium glutamicum. 1450 73

Aluminum inactivated glutamate dehydrogenase (GDH) by a pseudo-first-order reaction at micromolar concentrations. A double-reciprocal plot gave a straight line with a k(inact) of 2.7 min(-1) and indicated the presence of a binding step prior to inactivation. The inactivation was strictly pH dependent and a marked increase in sensitivity to aluminum was observed as the pH decreased. At a pH higher than 8.5, no inactivation was observed. The completely inactivated GDH contained 2 mol of aluminum per mole of enzyme subunit monomer. When preincubated with enzyme, several chelators such as citrate, NaF, N-(2-hydroxyethyl) ethylenediaminetriacetic acid or ethylenediaminetriacetic acid efficiently protected the enzyme against the aluminum inactivation. In a related experiment, only citrate and NaF released the aluminum from the completely inactivated aluminum-enzyme complex and fully recovered the enzyme activity. Ferritin, NADP+, or nerve growth factor did not show any effects on the recovery of the aluminum-inactivated GDH activity. The dissociation constant for the aluminum-enzyme complex was calculated to be 5.3 microM. Although aluminum has been known to form a complex with nucleotides, no such effects were observed in the inactivation of GDH by aluminum as determined using GDHs mutated at the ADP-binding site, NAD+-binding site or GTP-binding site. Circular dichroism studies showed that the binding of aluminum to the enzyme induced a decrease in alpha helices and beta sheets and an increase in random coil. Therefore, inactivation of GDH by aluminum is suggested to be due to the conformational change induced by aluminum binding. These results suggest a possibility that aluminum-induced alterations in enzymes of the glutamate system may be one of the causes of aluminum-induced neurotoxicity.
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PMID:Inactivation of human glutamate dehydrogenase by aluminum. 1462 97

The trans-(+/-)-1,2-diaminocyclohexaneplatinum(II) complexes of multidentate L-glutamate (Glu) and L-aspartate (Asp) were prepared and their antitumor activity was examined in relation with their coordination modes. All these complexes were obtained as a mixture of (O,O')- and (O,N)-chelate isomers due to rapid isomerization of the initially formed (O,O')-isomer to the thermodynamically more stable (O,N)-isomer. The (O,O')/(O,N)-isomeric mixture with the mole ratio of 80/20 exhibited excellent antitumor activity while the pure (O,N)-isomer was only marginally active. Therefore, in order to prevent the linkage isomerization of the active (O,O')-isomer to the inactive (O,N)-isomer, we have designed N-substituted amino dicarboxylic acids as a leaving group and prepared a new series of complexes, [Pt(dach)(RGlu)] and [Pt(dach)(RAsp)] (dach=trans-(+/-)-1,2-diaminocyclohexane; R=acetyl (Ac), propionyl (Pro), pivaloyl (Piv), carbobenzyloxy (Cbz) or phthaloyl (Phth)) and characterized by means of elemental analyses, and 1H NMR, 195Pt NMR and IR spectroscopies. The N-substituted amino dicarboxylate ligands were found to coordinate to platinum(II) ion through only the (O,O')-chelation mode, and their Pt(II) complexes were chemically stable in aqueous solution. The present Pt(II) complexes of N-substituted amino dicarboxylic acids showed excellent antitumor activity against both murine leukemia L1210 and human tumor cells. Especially, the highly hydrophobic N-phthaloylglutamate complex, [Pt(dach)(PhthGlu)], exhibited an outstanding in vitro activity (IC50=2.22 microM) on the human stomach cancer cells which are not responsive to cisplatin and carboplatin.
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PMID:Coordination modes vs. antitumor activity: synthesis and antitumor activity of novel platinum(II) complexes of N-substituted amino dicarboxylic acids. 1465 38

We present results of applied field nonequilibrium molecular dynamics simulations (AF NEMD) of a minimal beta-barrel model channel intended to represent an L-type calcium channel that suggests a possible relationship between glutamate side chain conformational changes and ion flux in calcium channels. The beta-barrel is used to provide a scaffolding for glutamate side chains and a confinement for electrolyte of dimensions similar to the expected channel structure. It was preloaded with ions to explore relative rates of ion exit for different occupancy configurations. Our simulations with an asymmetrical flexible selectivity filter represented by four glutamate side chains (EEEE), one of which differs in initial dihedrals from the other three, indicate a plausible mechanism for the observed anomalous mole fraction effect seen in calcium channels. Apparent rates of electric field-induced exit from channels preloaded with three Na+ ions are much higher than for channels with one Ca2+ followed by two Na+ ions, consistent with the common notion that Ca2+ block of Na+ current is due to competition between the Ca2+ and Na+ ions for the negatively charged (EEEE) locus. In our model, the Ca2+ ion ligates simultaneously to the four negatively charged glutamate side chains and sterically blocks the permeation pathway. Ca2+-relief of Ca2+-block is suggested by a much higher rate of exit for channels preloaded with three Ca2+ ions than for channels with two Ca2+ ions.
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PMID:Applied field nonequilibrium molecular dynamics simulations of ion exit from a beta-barrel model of the L-type calcium channel. 1523 53

The secreted phospholipase A(2) from bee venom (bvPLA(2)) contains a membrane binding surface composed mainly of hydrophobic residues and two basic residues that come in close contact with the membrane. Previous studies have shown that the mutant in which these two basic residues (K14 and R23) as well as three other nearby basic residues were collectively changed to glutamate (charge reversal), like wild-type enzyme, binds with high affinity to anionic phospholipid vesicles. In the present study, we have measured the equilibrium constants for the interaction of wild-type bvPLA(2), the charge-reversal mutant (bvPLA(2)-E5), and the mutant in which the five basic residues were changed to neutral glutamine (bvPLA(2)-Q5) with phosphatidylcholine (PC) vesicles containing various amounts of the anionic phosphatidylserine (PS). Remarkably, bvPLA(2)-E5 with an anionic membrane binding surface binds more tightly to vesicles as the mole percent of PS is increased. Computational studies predict that this is due to a significant upward shift in the pK(a) of E14 (and to some extent E23) when the enzyme binds to PC/PS vesicles such that the carboxylate of the glutamate side chain near the membrane surface undergoes protonation. The experimental pH dependence of vesicle binding supports this prediction. bvPLA(2)-E5 binds more weakly to PS/PC vesicles than does wild-type enzyme due to electrostatic protein-vesicle repulsion coupled with the similar energetics of desolvation of basic residues and glutamates that accompanies enzyme-vesicle contact. Studies with bvPLA(2)-Q5 show that only a small fraction of the total bvPLA(2) interfacial binding energy ( approximately 10%) is due to electrostatics.
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PMID:Interfacial binding of bee venom secreted phospholipase A2 to membranes occurs predominantly by a nonelectrostatic mechanism. 1549 Nov 36

Screening tests for glutamate producing strains were carried out, with the media containing carbohydrate and ammonia source as chief ingredients. Glutamate as well as certain other amino acids was detected by paper chromatography in culture broth of many microorganisms tested. Accumulation of L-glutamate in a significant amount (at least a few mg of glutamate per ml of broth) has been demonstrated by various strains of bacteria, streptomycetes, yeasts, and fungi. The highest level of glutamate production has been obtained by a new species of Micrococcus, yielding as much as 0.25 mole of it from one mole of glucose. The courses of fermentations mainly by known strains of microorganisms are shown. The importance of the cultural condition and strain specificity for the production of amino acids are briefly described.
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PMID:Studies on the amino acid fermentation. Part 1. Production of L-glutamic acid by various microorganisms. 1596 88

Illuminated pea (Pisum sativum) chloroplasts actively catalyzed (glutamine plus alpha-ketoglutarate)-dependent O(2) evolution (average of 12 preparations 10.6 mumole mg chlorophyll per hour). The reaction was specific for glutamine and alpha-ketoglutarate; concentrations of 0.2 mm alpha-ketoglutarate and 0.6 mm glutamine, respectively, effected half-maximum rates of O(2) evolution. The reaction was inhibited by 3-(3,4-dichlorophenyl)-1-1-dimethylurea and did not occur in the dark. After osmotic shock chloroplasts did not catalyze O(2) evolution. The reaction was inhibited by azaserine and glutamate but not by 10 mm ammonia, 2.5 mm methionine sulfoximine, or 5 mm amino-oxyacetate; addition of amino-oxyacetate together with aspartate inhibited O(2) evolution. Arsenate (3 mm) enhanced O(2) evolution. The highest molar ratio for O(2) evolved per mole of alpha-ketoglutarate supplied was 0.40; the corresponding values for glutamine in the absence and presence of 3 mm arsenate were 0.20 and 0.24, respectively. The (glutamine plus alpha-ketoglutarate)-dependent O(2) evolution is attributed to photosynthetically coupled glutamate synthase activity and the activity is sufficient to account for the assimilation of inorganic nitrogen. The low molar ratio for glutamine is discussed.Chloroplasts also catalyzed (aspartate plus alpha-ketoglutarate)-dependent O(2) evolution but this reaction was inhibited by 5 mm amino-oxyacetate and it was insensitive to azaserine and methionine sulfoximine. This reaction was attributed to transaminase and photosynthetically coupled malate dehydrogenase activities.
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PMID:A polarographic study of glutamate synthase activity in isolated chloroplasts. 1666 92

The amino acid composition of endosperm cavity sap and of sieve tube saps from the flag leaf, peduncle, rachis, grain pedicel, and grain were determined for wheat plants just past the mid-half of grain filling. On a mole percent basis, glutamine accounted for almost half of the amino acids in sieve tube sap from the peduncle and ear. Other protein amino acids, plug gamma-aminobutyrate, were present in varying, but mostly low (a few mole percent) proportions. The amino acid composition of phloem exudate resembled that of the mature wheat grain. The proportions of amino acids in the endosperm cavity were generally similar to those of the sieve tube sap supplying the grain. Cysteine, however, while virtually absent from sieve tube sap, comprised 1 to 2 mole percent of amino acids in the endosperm cavity, suggesting it is transported in a different form. Also, alanine and, to a lesser extent, glutamate were relatively more prominent in endosperm cavity sap than in the sieve tube sap. Thus, while most amino acids were more concentrated in the sieve tube sap than in the endosperm cavity sap, alanine and glutamate appeared to be moving from the sieve tube to the endosperm cavity in the absence of, or perhaps even against, their concentration gradients.
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PMID:Amino Acid Composition Along the Transport Pathway during Grain Filling in Wheat. 1666 28


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