The effect of growth hormone on the incorporation of N15 from ammonium citrate, glycine, L-aspartic acid, L-alanine and L-glutamic acid into amino acids of liver protein.
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Alanine↗
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Imaging of tumors involving bone with 13N-glutamic acid.
Nitrogen-13 labeled L-glutamic acid was evaluated as an imaging agent for tumors involving bone. The enzymatically prepared labeled compound was administered intravenously to dogs with spontaneous tumors, and tumor uptake was determined with a gamma camera and rectilinear scanner. These tumors were well visualized with 13N-glutamic acid, and the results compared favorably with uptake studies performed on the same animals with 99mTc-diphosphonate.
Animals↗
A conserved glutamic acid bridge in serine carboxypeptidases, belonging to the alpha/beta hydrolase fold, acts as a pH-dependent protein-stabilizing element.
Serine endopeptidases of the chymotrypsin family contain a salt bridge situated centrally within the active site, the acidic component of the salt bridge being adjacent to the catalytically essential serine. Serine carboxypeptidases also contain an acidic residue in this position but it interacts through a short hydrogen bond, probably of low-barrier type, with another acidic residue, hence forming a "glutamic acid bridge." In this study, the residues constituting this structural element in carboxypeptidase Y have been replaced by site-specific mutagenesis. It is demonstrated that the glutamic acid bridge contributes significantly to the stability of the enzyme below pH 6.5 and has an adverse effect at pH 9.5. Carboxypeptidase WII from wheat contains 2 such bridges, and it is more stable than carboxypeptidase Y at acidic pH.
Amino Acid Sequence↗
Optimization of cell growth and poly(glutamic acid) production in batch fermentation by Bacillus subtilis.
Poly(glutamic acid) was produced maximally by Bacillus subtilis in batch fermentations at pH 7 and using glycerol at 20 g l(-1) in a glutamic acid/citric acid medium. Poly(glutamic acid) reached 23 g l(-1) after 30 h.
Bacillus subtilis↗
Fragmentation reactions of protonated peptides containing glutamine or glutamic acid.
A variety of protonated dipeptides and tripeptides containing glutamic acid or glutamine were prepared by electrospray ionization or by fast atom bombardment ionization and their fragmentation pathways elucidated using metastable ion studies, energy-resolved mass spectrometry and triple-stage mass spectrometry (MS(3)) experiments. Additional mechanistic information was obtained by exchanging the labile hydrogens for deuterium. Protonated H-Gln-Gly-OH fragments by loss of NH(3) and loss of H(2)O in metastable ion fragmentation; under collision-induced dissociation (CID) conditions loss of H-Gly-OH + CO from the [MH - NH(3)](+) ion forms the base peak C(4)H(6)NO(+) (m/z 84). Protonated dipeptides with an alpha-linkage, H-Glu-Xxx-OH, are characterized by elimination of H(2)O and by elimination of H-Xxx-OH plus CO to form the glutamic acid immonium ion of m/z 102. By contrast, protonated dipeptides with a gamma-linkage, H-Glu(Xxx-OH)-OH, do not show elimination of H(2)O or formation of m/z 102 but rather show elimination of NH(3), particularly in metastable ion fragmentation, and elimination of H-Xxx-OH to form m/z 130. Both the alpha- and gamma-dipeptides show formation of [H-Xxx-OH]H(+), with this reaction channel increasing in importance as the proton affinity (PA) of H-Xxx-OH increases. The characteristic loss of H(2)O and formation of m/z 102 are observed for the protonated alpha-tripeptide H-Glu-Gly-Phe-OH whereas the protonated gamma-tripeptide H-Glu(Gly-Gly-OH)-OH shows loss of NH(3) and formation of m/z 130 as observed for dipeptides with the gamma-linkage. Both tripeptides show abundant formation of the y(2)'' ion under CID conditions, presumably because a stable anhydride neutral structure can be formed. Under metastable ion conditions protonated dipeptides of structure H-Xxx-Glu-OH show abundant elimination of H(2)O whereas those of structure H-Xxx-Gln-OH show abundant elimination of NH(3). The importance of these reaction channels is much reduced under CID conditions, the major fragmentation mode being cleavage of the amide bond to form either the a(1) ion or the y(1)'' ion. Particularly when Xxx = Gly, under CID conditions the initial loss of NH(3) from the glutamine containing dipeptide is followed by elimination of a second NH(3) while the initial loss of H(2)O from the glutamic acid dipeptide is followed by elimination of NH(3). Isotopic labelling shows that predominantly labile hydrogens are lost in both steps. Although both [H-Gly-Glu-Gly-OH]H(+) and [H-Gly-Gln-Gly-OH]H(+) fragment mainly to form b(2) and a(2) ions, the latter also shows elimination of NH(3) plus a glycine residue and formation of protonated glycinamide. Isotopic labelling shows extensive mixing of labile and carbon-bonded hydrogens in the formation of protonated glycinamide.
Deuterium↗
Site-directed mutagenic alteration of potential active-site residues of the A subunit of Escherichia coli heat-labile enterotoxin. Evidence for a catalytic role for glutamic acid 112.
Escherichia coli heat-labile enterotoxin (LT) and the related cholera toxin exert their effects on eukaryotic cells through the ADP-ribosylation of guanine nucleotide-binding proteins of the adenylate cyclase complex. The availability of the crystal structure for LT has permitted the tentative identification of residues that lie within or are vicinal to a presumptive NAD(+)-binding site and thus may play a role in substrate binding or catalysis. Using a plasmid clone encoding the A subunit of LT, we have introduced substitutions at such potential active-site residues and analyzed the enzymatic properties of the resultant mutant analogs. Enzymatic analyses, employing both transducin and agmatine as acceptor substrates, revealed that substitutions at serine 61, glutamic acid 110, and glutamic acid 112 resulted in reduction of enzyme activity to < 10% of wild-type levels. Kinetic analyses indicated that alteration of these sites affected the catalytic rate of the enzyme and had little or no effect on the binding of either NAD+ or agmatine. Of the mutant analogs analyzed, only glutamic acid 112 appeared to represent an essential catalytic residue as judged by the relative effects on kcat and kcat/Km. The results provide formal evidence that glutamic acid 112 of the A subunit of LT represents a functional homolog or analog of catalytic glutamic acid residues that have been identified in several other bacterial ADP-ribosylating toxins and that it may play an essential role in rendering NAD+ susceptible to nucleophilic attack by an incoming acceptor substrate.
Amino Acid Sequence↗
Metabolism of glutamic acid in Aspergillus ochraceus during the biosynthesis of ochratoxin A.
The uptake and utilization of glutamic acid in the biosynthesis of ochratoxin A by Aspergillus ochraceus were studied. Uniformly labeled L[14C]glutamic acid was incorporated into both the phenylalanine and isocoumarin moieties of ochratoxin A. Penicillic acid was also labeled. During the early stages of development, the amino acid was used mainly for the synthesis of ribonucleic acid and protein. A portion of glutamic acid was oxidized and was recovered as metabolic 14CO-2. The initial uptake velocity of glutamic acid decreased with age and was pH and temperature dependent. No relationship was found between the initial uptake velocities and ochratoxin A biosynthesis.
Aspergillus↗
Folic acid deficiency and urinary formimino-glutamic acid excretion in the rat.
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Animals↗
Monte Carlo studies on potentiometric titration of poly(glutamic acid).
The potentiometric titration of poly(glutamic acid) with special attention to its helix-coil transition is investigated in terms of the previously developed Monte Carlo method. The simulations of the potentiometric titration are carried out for helical and coiled form of the peptide, separately. A cylindrical rod with spherical ionizable groups is adopted as each conformational model of poly(glutamic acid) molecule. A spherical charge with a hard core potential is assumed as a mobile hydrated ion. The helix-coil transition curves are analyzed by the Zimm-Bragg theory. A satisfactory agreement is achieved for the titration curves with the experimental data in most cases. The significance and the limitations of the simulation method are discussed.
Journal Article↗
Rheology, oxygen transfer, and molecular weight characteristics of poly(glutamic acid) fermentation by Bacillus subtilis.
Poly(glutamic acid) (PGA) is a water-soluble, biodegradable biopolymer that is produced by microbial fermentation. Recent research has shown that PGA can be used in drug delivery applications for the controlled release of paclitaxel (Taxol) in cancer treatment. A fundamental understanding of the key fermentation parameters is necessary to optimize the production and molecular weight characteristics of poly(glutamic acid) by Bacillus subtilis for paclitaxel and other applications of pharmaceuticals for controlled release. Because of its high molecular weight, PGA fermentation broths exhibit non-Newtonian rheology. In this article we present experimental results on the batch fermentation kinetics of PGA production, mass transfer of oxygen, specific oxygen uptake rate, broth rheology, and molecular weight characterization of the PGA biopolymer.
Bacillus subtilis↗
Free glutamic acid content of milk in Indian mothers.
Free amino acids levels in the milk of 11 healthy Indian mothers were determined using automatic precolumn derivatization procedure. The aim of the study was to find out the relative concentration of glutamic acid and glutamine in the milk. Glutamic acid is the dominant free amino acid found in the milk of Indian mothers. Glutamic acid and glutamine together formed the major nonessential amino acids present in the human milk. Although glutamic acid has been shown to be the major amino acid in human milk in many studies, to the best our knowledge, this is the first report to confirm that glutamic acid is the most abundant amino acid in milk in Indian mothers.
Adult↗
[A model of enzymatic decarboxylation of glutamic acid].
Interaction of glutamate decarboxylase with its adequate substrate and some quasi-substrates was studied by spectrokinetic, quantum-chemical and some other approaches. It was shown that in the course of decarboxylation an abortive transamination of pyridoxal-5'-phosphate leading to the enzyme inactivation does occur. Identification of intermediate coenzyme-substrate complexes allowed to formulate a model of enzymatic decarboxylation taking into account both the main and abortive reactions. The analysis of electronic structure of the intermediates revealed some of the factors determining the functional specificity of the reaction under study.
Circular Dichroism↗
Alpha-methyl-L-glutamic acid uptake by high affinity dicarboxylic amino acid transport system in Streptococcus faecalis.
The transport of alpha-methyl-L-glutamic acid was studied in Streptococcus faecalis. Energey-dependent uptake against substantial concentration gradients was observed. Kinetic experiments indicated that, in contrast to L-glutamic acid, only a single catalytic component (high affinity) and a diffusion controlled process participated in alpha-methyl-L-glutamic acid uptake. At concentrations up to 10 mM, alpha-methyl-glutamate transport was almost completely abolished in a mutant strain lacking a high affinity dicarboxylic amino acid transport system. In competition experiments, alpha-methylglutamic acid antagonized glutamate uptake via the high affinity system, and only slightly via the low affinity system. Column chromatography of cell extracts showed that very little (approx. 5%) of the accumulated amino acid was converted to metabolites during short term incubations. These studies indicate that, at concentrations up to 3-5 mM, alpha-methyl-L-glutamic acid can be used as a specific, relatively metabolically inert substrate of the high affinity dicarboxylic amino acid transport system in S. faecalis.
Amino Acids, Dicarboxylic↗
Isomers and homologues of L-glutamic acid 5-n-butyl ester as promoters of sediment formation in raw soy sauce.
Soy sauce was found to contain promoters of sediment formation at 60 degrees C, one of which has previously been identified as L-glutamic acid 5-n-butyl ester. Isomers and homologues of L-glutamic acid 5-n-butyl ester (n-propyl, isopropyl, n-butyl, isobutyl, and sec-butyl esters of L-glutamic acid) were synthesized using 80% (w/w) sulfuric acid as a catalyst and identified by 1H-NMR and the ninhydrin test. The yields of L-glutamic acid 5-n-propyl, isopropyl, n-butyl, isobutyl, and sec-butyl esters from 10 g L-glutamic acid were 25, 101, 72, 130, and 134 micromol, respectively. For maximum sediment formation in 1 ml soy sauce, 1.2, 8.6, 22.0, 22.0, and 26.5 micromol/ml of n-butyl, n-propyl, isobutyl, sec-butyl, and isopropyl esters were respectively required. Sediment-forming activity was not observed with L-glutamic acid and L-glutamic acid 5-methyl, ethyl and tert-butyl esters.
Journal Article↗
Effects of neurotransmitter candidates on 45Ca uptake by cortical slices of rat brain: stimulatory effect of L-glutamic acid.
The effects of neurotransmitter candidates and the characteristics of the stimulatory effect of L-glutamic acid (L-Glu) on 45Ca uptake by rat brain slices were investigated. 45Ca uptake was significantly stimulated by acetylcholine, serotonin and especially L-Glu, but not by other neurotransmitter candidates. L-Glu caused dose-dependent stimulation of 45Ca uptake (L-Glu-stimulated 45Ca uptake), its effect being half-maximal at 1 microM. The related compounds D-glutamic acid, D,L-alpha-aminoadipic acid and N-methyl-D,L-glutamic acid (final conc. of 10 microM) also stimulated 45Ca uptake, but less than 10 microM L-Glu. D,L-alpha-Methylglutamic acid and L-glutamic acid diethylether (final conc. of 10 microM), which are specific inhibitors of L-Glu, inhibited L-Glu-stimulated 45Ca uptake. Mg,Ca-ATPase activity was hardly affected by a concentration of 10 microM L-Glu that caused maximal stimulation of 45Ca uptake. These findings suggest that L-Glu-stimulated 45Ca uptake by brain cortical slices is linked to L-Glu receptor.
Acetylcholine↗
Enhanced glutamic acid production by a H+-ATPase-defective mutant of Corynebacterium glutamicum.
Previously we reported that a mutant of Corynebacterium glutamicum ATCC14067 with reduced H+-ATPase activity, F172-8, showed an approximately two times higher specific rate of glucose consumption than the parent, but no glutamic acid productivity under the standard biotin-limited culture conditions, where biotin concentration was set at 5.5 microg/l in the production medium (Sekine et al., Appl. Microbiol. Biotechnol., 57, 534-540 (2001)). In this study, various culture conditions were tested to check the glutamic acid productivity of strain F172-8. The mutant was found to produce glutamic acid under exhaustive biotin limitation, where the biotin concentration of the medium was set at 2.5 microg/l with much smaller inoculum size. When strain F172-8 was cultured under the same biotin-limited conditions using a jar fermentor, 53.7 g/l of glutamic acid was produced from 100 g/l glucose, while the parent produced 34.9 g/l of glutamic acid in a medium with 5.5 microg/l biotin. The glutamic acid yield of strain F172-8 also increased under Tween 40-triggered production conditions (1.2-fold higher than the parent strain). The amounts of biotin-binding enzymes were investigated by Western blot analysis. As compared to the parent, the amount of pyruvate carboxylase was lower in the mutant; however, the amount of acetyl-CoA carboxylase did not significantly change under the glutamic acid production conditions. To the best of our knowledge, this is the first report showing that the H+-ATPase-defective mutant of C. glutamicum is useful in glutamic acid production.
Biotin↗
N-acetyl-L-glutamic acid.
In the structure of N-acetyl-L-glutamic acid, C7H11NO5, each molecule is directly hydrogen bonded to four others by a total of six hydrogen bonds. Two carboxylic O atoms and the N atom are donors, while all three acceptors are O atoms. There is also an intramolecular hydrogen bond with the N atom as donor and a carboxylic O atom as acceptor. The carboxyl O and H atoms are ordered. The conformation of the carbon chain with respect to the C3-C4 bond is trans as in L-glutamic acid hydrochloride, rather than gauche as in the beta form of L-glutamic acid.
Glutamates↗
Studies in metabolic spectra. IV. Effects of tetracyclines, some of their derivatives, and chloramphenicol on accumulation of glutamic acid in Escherichia coli.
Cheng, Lorraine (Radiobiochemistry Department, Chas. Pfizer & Co., Inc., Maywood, N. J.) and J. F. Snell. Studies in metabolic spectra. IV. Effects of tetracyclines, some of their derivatives, and chloramphenicol on accumulation of glutamic acid in Escherichia coli. J. Bacteriol. 83:711-719. 1962.-Escherichia coli strain 21 was incubated in the Warburg apparatus at 37 C with sodium acetate-2-C(14) and 0.1 mumole/ml of various test compounds. Up to 1 hr, de novo C(14)-glutamic acid (synthesized from the C(14)-acetate precursor) accumulation in the fermentation broth was found to be a common phenomenon for the control cells and cells treated with oxytetracycline, chlortetracycline, tetracycline, and chloramphenicol. Subsequently, C(14)-glutamic acid continued to accumulate in the broth of the inhibited cells, but began to disappear from the broth of the control cells. During the first half hour, the rate of accumulation was most rapid in the presence of oxytetracycline. At 3 hr the total de nova C(14)-glutamic acid was found to be the same whether cells were treated with oxytetracycline or not. However, the distribution of this glutamic acid was different. In the oxytetracycline-treated cells, more than 87% of the total de nova C(14)-glutamic acid was in the broth, and only 13% was incorporated into the cell residue. In the control cells, no C(14)-glutamic acid was found in the broth, although 67% was in the cell residue. The possibility that the tetracyclines and chloramphenicol have different modes of action, and that oxytetracycline inhibits the incorporation of d-glutamic acid into the cell wall and membrane material in E. coli 21, was discussed.
Chloramphenicol↗