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PubMed1977

Integrated excitatory response to microinjections of L-glutamic acid into the reticular system of the toad.

Microinjections of L-glutamic acid into the mesencephalic tegmentum and diencephalon of anesthetized toads evoked an excitatory response consisting of electrocephalographic and electromyographic activation, and a rise in arterial blood pressure. Electromyographic responses were reduced or absent in diencephalically injected toads. Except for this case, all other components of the response always appeared together and presented the same time course. L-glutamic acid was able to activate a group of neurons at different levels of the reticular system involved in an integrated response of ergotropic nature.

Animals↗
PubMed1991

A novel selective NMDA agonist, N-phthalamoyl-L-glutamic acid (PhGA).

Ionic currents elicited by N-phthalamoyl-L-glutamic acid (PhGA) were investigated on freshly isolated hippocampal neurons with the whole-cell voltage clamp and concentration clamp techniques. PhGA elicited desensitizing inward currents in Mg(2+)-free salines only in the presence of glycine. The dose-response relationship for PhGA was close to a Langmuir isotherm with Kd = 3.7 mM and saturating level 0.75 of that for L-aspartate (L-Asp). PhGA-activated currents were blocked by Mg2+, D-2-amino-5-phosphonovalerate and kynurenate, and had the same reversal potential as L-Asp-activated currents. Complete cross-desensitization was obtained between the responses to PhGA and L-Asp. We conclude that PhGA is a new selective 'superacidic' agonist of the N-methyl-D-aspartate type of glutamate receptor.

Animals↗
PubMed1986

Inhibition of quisqualate-induced seizures by glutamic acid diethyl ester and anti-epileptic drugs.

Glutamic acid diethyl ester (GDEE) is a glutamate antagonist which acts preferentially at the quisqualate-sensitive receptor and has been shown to be an effective anticonvulsant in alcohol withdrawal and homocysteine-induced seizures but ineffective in other seizure models. To better characterize the role of the quisqualate-sensitive receptor in the generation of seizures, quisqualate was administered to mice by intracerebroventricular (ICV) route and immediate onset generalized seizures were observed. The anticonvulsant properties of GDEE and commonly used antiepileptic drugs (AEDs) were investigated with this seizure model. GDEE given by intraperitoneal blocked quisqualate-induced seizures dose-dependently. Diphenyl-hydantoin (50 mg/kg IP), carbamazepine (50 mg/kg IP), diazepam (1; 4 mg/kg IP), phenobarbital (40; 80 mg/kg IP), and valproic acid (250; 340 mg/kg IP) were also administered prior to quisqualate-seizure induction. Only valproic acid blocked seizures at nonsedating doses. The GABA transaminase inhibitor aminooxyacetic acid (20 mg/kg IP) was ineffective, suggesting that here valproic acid is active at excitatory receptors rather than by potentiating GABA post-synaptic inhibition. These data are consistent with the hypothesis that the quisqualate-sensitive receptor is involved in some forms of clinically observed seizures, particularly those which are controlled by valproic acid.

Aminooxyacetic Acid↗
PubMed1972

Spore pool glutamic acid as a metabolite in germination.

Spore glutamic acid pools were examined in dormant and germinating spores using colorimetric and (14)C analytical procedures. Germination of spores of Bacillus megaterium (parent strain), initiated by d-glucose, was accompanied by a rapid drop in the level of spore pool glutamate, from 12.0 mug/mg of dry spores to 7.7 mug/mg of dry spores after 30 sec of germination. Similar decreases in extractable spore pool glutamate were observed with l-alanine-initiated germination of B. licheniformis spores. On the other hand, glutamate pools of mutant spores of B. megaterium, with a requirement of gamma-aminobutyric acid for spore germination, remained unchanged for 9 min of germination, at which time more than 50% of the spore population had germinated. Evidence for conversion of spore pool glutamate to gamma-aminobutyric acid during germination of spores of B. megaterium (parent strain) was obtained.

Alanine↗
PubMed1996

The glutamic acid residue at amino acid 261 of the alpha subunit is a determinant of the intrinsic efficiency of RNA polymerase at the metE core promoter in Escherichia coli.

A mutation in the rpoA gene (which encodes the alpha subunit of RNA polymerase) that changed the glutamic acid codon at position 261 to a lysine codon decreased the level of expression of a metE-lacZ fusion 10-fold; this decrease was independent of the MetR-mediated activation of metE-lacZ. Glutamine and alanine substitutions at this position are also metE-lacZ down mutations, suggesting that the glutamic acid residue at position 261 is essential for metE expression. In vitro transcription assays with RNA polymerase carrying the lysine residue at codon 261 indicated that the decreased level of metE-lacZ expression was not due to a failure of the mutant polymerase to respond to any other trans-acting factors, and a deletion analysis using a lambda metE-lacZ gene fusion suggested that there is no specific cis-acting sequence upstream of the -35 region of the metE promoter that interacts with the alpha subunit. Our data indicate that the glutamic acid at position 261 in the alpha subunit of RNA polymerase influences the intrinsic ability of the enzyme to transcribe the metE core promoter.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2006

Blood compatibility of novel poly(gamma-glutamic acid)/polyvinyl alcohol hydrogels.

Sodium poly(gamma-glutamic acid) (PGA), a water-soluble and biodegradable polypeptide, was reacted with polyvinyl alcohol (PVA) to form hydrogel without any chemical treatment. The gelation occurred probably due to physical cross-linking of polymer chains by interpenetrating hydrogen bonding. From the results of thermal analysis, PGA/PVA exhibited better thermal stability than native PVA. Although the swelling ratio decreased with the increase of PGA content, however, the water resistance and retention were improved. The tensile strength of the PGA/PVA hydrogel membranes was about 15-30% lower than that of the native PVA, whereas the elongation was increased 2.0-2.6 times. The amount of protein adsorbed and platelets adhered on the PGA/PVA membranes were significantly curtailed with increasing PGA content, thereby showing improved blood compatibility. The as-fabricated hydrogels were proven to be non-cytotoxic evaluated in vitro by L-929 fibroblast incubation. Overall results demonstrate that the non-cytotoxic PGA/PVA hydrogels, due to better water resistance, mechanical properties and blood compatibility could be very promising candidates for blood-contacting medical devices.

Animals↗
PubMed1983

Mg2+-, Ca2+-dependent unwinding of DNA by poly-L-glutamic acid.

In order to examine a possibility that the high acidic amino acid region in the nonhistone protein HMG(1+2) is concerned with the Mg2+-, or Ca2+-dependent unwinding of DNA by the HMG(1+2) (1,2), poly-L-glutamic acid was employed as an acidic model peptide for thermal melting temperature analysis. The poly-L-glutamic acid bound to DNA either in the presence or absence of Mg2+. The poly-L-glutamic acid unwound DNA double-helix to a similar extent to HMG(1+2) in the presence of Mg2+ or Ca2+, but not in the absence of them. These results may suggest that the high acidic amino acid region in HMG(1+2) participates in Mg2+-, Ca2+-dependent unwinding of DNA double-helix.

Animals↗
PubMed1990

Structural studies of acidic polymers produced by the O23 reference strain of Serratia marcescens: presence of amide-linked glutamic acid.

The major fraction of an acidic galactoglucomannan present in lipopolysaccharide extracts from cell walls of the O23 reference strain of Serratia marcescens has the tetrasaccharide repeating-unit shown. In a minor fraction, L-glutamic acid was amide-linked to about half of the D-glucuronic acid residues. The possible contributions of the acidic polymers and a neutral polymer produced by the organism to cross-reactions with other serogroups are discussed.

Acids↗
PubMed1981

Glutamic acid in nervous tissue and changes of the taurine content: its implication in the treatment of epilepsy.

In order to account for interdependent changes in the steady state cerebral levels of glutamic acid, taurine and glutamine, two compartments are considered which are connected by an adjustable flow valve. The first compartment may be equated with neuronal structures and confines most of the steady state content of glutamic acid. The second compartment represents glia and contains most cerebral glutamine; taurine is sequestered by both anatomic compartments. The adjustable valve symbolises a combination of rate limited release, transport, and enzymic mechanisms responsible for connecting the glutamate containing structures with those sequestering glutamine. These compartments only represent a portion of the total intracerebral metabolism of glutamic acid (see 19).

Animals↗
PubMed1982

Effect of kainic acid, glutamate, and aspartate on CO2 production by goldfish tectal slices.

For a study of the excitatory effect of kainate, glutamate, and aspartate in the goldfish optic tectum, these substances were tested on the production of CO2 from radioactive glucose in tectal slices incubated in Krebs-Ringer medium for fish. Kainate increased the rate of CO2 production for up to 30 min in a dose-related manner, the effect being maximum at 0.1 mM concentration and decreasing at higher doses. The effect was blocked by ouabain (1 mM) as well as by the substitution of choline for Na+ in the incubation medium. Glutamate and aspartate exerted a less pronounced excitatory effect on CO2 production at higher concentration than kainate. This effect was also abolished by ouabain. Glutamate, added to the medium at a concentration at least 100-fold higher than kainate, partially reversed the increase in CO2 production induced by kainic acid. No similar effect was noticed for aspartate. The supposed glutamate antagonists glutamic acid diethylester (1 mM) and proline (5 mM) did not affect the excitatory action of kainic acid or exert an antagonistic effect towards glutamate. At higher concentration (10 mM) glutamic acid diethylester increased CO2 production, an effect that was, however, ouabain insensitive. Methyltetrahydrofolic acid (1 mM), a substance reported to compete for the kainate receptor, did not inhibit the effect of kainic acid or increase CO2 production.

Animals↗
PubMed2002

Spiro[2.2]pentane as a dissymmetric scaffold for conformationally constrained analogues of glutamic acid: focus on racemic 1-aminospiro[2.2]pentyl-1,4-dicarboxylic acids.

In search for novel conformationally constrained analogues of L-glutamic acid, a diastereodivergent synthesis of the four 1-aminospiro[2.2]pentyl-1,4-dicarboxylic acid racemic pairs is reported along with their stereochemical assignment, conformational analysis, and preliminary biological evaluation as potential glutamate (ionotropic and metabotropic) ligands.

Dicarboxylic Acids↗
PubMed1967

Intracellular localization of nitrate reductase, nitrite reductase, and glutamic Acid dehydrogenase in green leaf tissue.

Greenhouse grown seedlings of corn (Zea mays L.) and foxtail (Setaria faberii Herrm.) were used as source material in determining the intracellular localization of nitrate reductase, nitrite reductase, and glutamic acid dehydrogenase, Nonaqueous and aqueous isolation techniques were used to establish that nitrite reductase is localized within the chloroplasts, but that nitrate reductase and glutamic acid dehydrogenase are not. Nonaqueous isolation gives distribution patterns of nitrite reductase which are the same as those observed for NADP-dependent 3-phosphoglyceraldehyde dehydrogenase but which differ drastically from the patterns observed for pyruvic acid kinase. The distribution patterns for nitrate reductase are the same as those of pyruvic acid kinase. The techniques used do not eliminate the possibility that nitrate reductase and pyruvic acid kinase are localized on the external chloroplast membrane.The data obtained establish that glutamic acid dehydrogenase of green leaves is localized within the mitochondria.

Journal Article↗
PubMedDate not supplied

Enzymatic determination of free glutamic acid in dried soups and in minced sausages: NMKL collaborative study.

An enzymatic method for the determination of free glutamic acid in meat products and dried soups was collaboratively studied in 11 laboratories. In the presence of the enzyme glutamate dehydrogenase, L-glutamic acid is oxidatively deaminated by nicotinamide adenine dinucleotide (NAD) to 2-oxoglutarate. In a reaction catalyzed by diaphorase, the NADH thus formed converts 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride to a formazan, which is measured in the visible range at 492 nm. Fourteen samples (7 samples of minced sausage and 7 samples of dried cauliflower soup) with glutamate contents varying between 0.4 and 16 g/kg were included in the study. Materials were distributed to participants as blind duplicates and as split level pairs. The mean relative standard deviation (RSDR) for reproducibility for the dried soup material containing glutamate between 7 and 16 g/kg was 4.6%. RSDR values for samples of minced sausage containing glutamate at lower levels (0.4-1.3 g/kg) were between 12 and 16%.

Food Additives↗
PubMed1996

Effects of L-glutamic acid and its agonists on snail neurones.

The sensitivities of 22 giant neurone types of an African giant snail (Achatina fulica Férussac) to threo-beta-hydroxy-L-glutamic acid (threo-L-BHGA), a derivative of L-glutamic acid (L-Glu), applied by brief pneumatic pressure ejection, were examined under current clamp. The 5 neurone types were depolarized by this compound, whereas 2 were hyperpolarized. The 4 neurone types, PON (periodically oscillating neurone), RAPN (right anterior pallial nerve neurone), d-RPLN (dorsal-right parietal large neurone) and RPeNLN (right pedal nerve large neurone) that are excited by threo-L-BHGA and one type, v-LCDN (ventral-left cerebral distinct neurone), inhibited by this compound, were selected to study their pharmacological features in detail. Effects of the stereoisomers of L-Glu and threo-L-BHGA, and mammalian L-Glu receptor agonists, ejected by brief pressure, on the 5 Achatina neurone types were examined under voltage clamp. d-RPLN produced an inward current (Iin) by L-Glu and threo-L-BHGA, whereas this neurone type was insensitive to D-Glu and erythro-L-, threo-D- and erythro-D-BHGA. This was also excited by AMPA, indicating that the pharmacological features of the L-Glu receptors in this neurone type were similar to those of the mammalian ionotropic AMPA type L-Glu receptors. RAPN produced Iin by L-Glu and threo-L-BHGA. This neurone type was also excited by quisqualic acid and ibotenic acid, indicating that the features of the L-Glu receptors were similar to those of the mammalian metabotropic L-Glu receptors. PON and RPeNLN produced Iin by L-Glu and threo-L-BHGA. These neurone types were also excited by quisqualic acid, AMPA and ibotenic acid, indicating that their L-Glu receptors seemed to be in the mixed type, of the two types mentioned. On the other hand, v-LCDN produced an outward current (Iout) by threo-L- and erythro-L-BHGA, but was insensitive to L-Glu, indicating that the receptors activated by L-BHGA were not L-Glu receptors. This neurone type was also inhibited by quisqualic acid.

Animals↗
PubMedDate not supplied

[L-Glutamic acid modulates the cytotoxic effect of tumor necrosis factor in the HL-60 cell line].

L-Glutamic acid was shown to increase the stability of cells of the HL-60 line of human promyelocyte leukemia to the cytotoxic action of tumor necrosis factor alpha (TNF-alpha) due to the inhibition of apoptotic and NF-kappaB-activating cascades induced by this cytokine. At the same time, L-glutamic acid increases the TNF-alpha-mediated differentiating signal and the accompanying enhancement of the phosphatidylinositol-specific phospholipase C activity. Therefore, it is a promising agent for the reduction of total toxicity and inflammatory processes during treatment with TNF-alpha. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 6; see also http://www.maik.ru.

Antineoplastic Agents↗
PubMed1981

[The contribution of betaine and glutamic acid to nitrogen digestion and balance during feeding of vinasse to growing pigs].

A conventional balance trial was conducted with growing pigs to study to what extent betaine and glutamic acid contained in vinasse (condensed molasses solubles) contribute to N digestion and balance. Five pigs each were given either a basal diet (95% ground barley + 5% cellulose) or a mixed ration of 77% basal diet plus 23% vinasse, based on dry matter (DM). The vinasse contained, per kg DM, 29.6 g N, 27.7 g NPN, 22.5 g betaine, 32.9 g "free" total L-glutamic acid, of which 96% was pyrrolidone carboxylic acid plus glutamine. For these N fractions of the vinasse, mean apparent digestibilities were 44.7, 63.8, 99.8 and 97.6%, respectively. Accordingly, betaine and total glutamic acid contributed 20 and 23%, respectively, of the apparently digestible total N of the vinasse. The pigs given vinasse excreted, per day, 257 mg more betaine and 364 mg more trimethylamine-N-oxide with their urine than the group given the basal diet. The contribution of betaine N of the vinasse to the N balance of the pigs on the mixed ration amounted to 11%.

Animal Feed↗
PubMed1995

Quinazoline antifolate thymidylate synthase inhibitors: replacement of glutamic acid in the C2-methyl series.

The synthesis of a series of analogues of the potent thymidylate synthase (TS) inhibitor N-[4-[N-[(3,4-dihydro-2-methyl-4-oxo-6- quinazolinyl)methyl]-N-prop-2-ynylamino]benzoyl]-L-glutamic acid (ICI 198583, 1) is described in which the glutamic acid residue has been replaced by other alpha-amino acids. Most of these analogues were prepared by coupling of tert-butyl-4-(prop-2-ynylamino)benzoate (37) with 6-(bromomethyl)-3,4-dihydro-2-methyl-4-oxoquinazoline (34) followed by deprotection of the tert-butyl ester to the acid and azide-mediated coupling to the appropriate amino acid or amino acid ester. In cases where the amino acid ester was unreactive with the acid azide, a modification was used in which the quinazolinone moiety was protected as its 3-(pivaloyloxy)methyl derivative. This permitted the generation of the more reactive acid chloride of the p-aminobenzoate unit. In general these modifications result in compounds that have equivalent potency to 1 as inhibitors of isolated TS except where the amino acid lacks a lipophilic alpha-substituent. These compounds appear to require the reduced folate carrier (RFC) for transport into cells, but since they are not converted intracellularly into polyglutamated forms, they have a lower level of cytotoxicity compared to 1. The removal of the alpha-carboxylic acid has given a second set of analogues of 1 which contain simple alkyl amide, benzyl, substituted benzyl, and heterocyclic benzyl amide derivatives. These are considerably less potent than 1 as TS inhibitors but display 1-10 microM cytotoxicities due to the fact that they do not require RFC transport and can presumably readily enter cells by passive diffusion through the cell membrane. Molecular modeling and NMR studies indicated that the incorporation of, respectively, 7-methyl and 2'-fluoro substituents would favor the optimum conformation of these molecules for interaction with the TS enzyme. Accordingly, these substituents were incorporated into selected examples to give the series of analogues 47-55. These all show enhanced (approximately 10-fold) inhibition of TS compared to their unsubstituted counterparts. In the substituted benzylamides (51, 52) and heterocyclic benzyl amides (53-55) the ability to enter cells by passive diffusion results in highly potent (< 1 microM) cytotoxic agents.

Animals↗