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At least 199 records · Page 11Linked to original sources
PubMed1994

The addition of glutamic acid or protein to a threonine-deficient diet differentially affects growth performance and threonine dehydrogenase activity in fattening pigs.

The effects of dietary levels of threonine, protein (essential and nonessential amino acids) and glutamic acid (nonessential amino acid) on growth, food intake and threonine metabolism were studied in 54 fattening female pigs (Piétrain x Large White) from 40 to 100 kg live weight. Six experimental diets were compared using a 2 x 3 factorial design: two levels of threonine (0.42 and 0.52 g/100 g) corresponding to a limited and an adequate supply for growth, and three types of nitrogen supply: a basal diet supplying 12.6 g crude protein/100 g, a second diet providing additional protein to give a total supply of 15.6 g crude protein/100 g, and a third diet providing nonessential nitrogen in the form of L-glutamic acid to give the same total supply of 15.6 g crude protein/100 g diet. Protein addition to the basal diets did not modify growth performance but increased L-threonine-3-dehydrogenase (TDG) activity when pigs were fed the higher threonine diet. The addition of L-glutamic acid to the threonine-deficient diet improved growth performance, but there was no effect at the higher level of threonine. Glutamic acid increased TDG activity in pigs fed the low threonine diet. We conclude that glutamic acid may have a sparing effect on threonine when threonine is rate-limiting for protein deposition, but the mechanism of the interaction between the two amino acids remains unknown.

Alcohol Oxidoreductases↗
PubMed2001

[Preparation, characterization and characteristics of copolypeptide consisting of L-aspartic acid and L-glutamic acid].

For the purpose of increasing the hydrophilicity of poly-aspartic acid, a copolypeptide consisting of L-aspartic acid and L-glutamic acid (8: 2 mol/mol) was prepared. The copolymer was characterized by 1H NMR, 13C NMR, differential scanning calorimetry, X-ray and element analysis. 3-hydroxyamino, as a side chain, was linked to the polymer, and poly-(3-hydroxypropyl)-L-aspartamide-L-glutamide (PHPAG) was obtained. The molecular weight of PHPAG was determined by GPC. Tests of the PHPAG on laboratory animals corroborated its potential use as a drug carrier. Acute toxicity studies revealed no death in animals treated, other studies recorded no notable difference between treated and control animals either in terms of principal haematological parameters or in micronucleus test. In vitro enzymatic hydrolysis for the co-polymer was performed using chymotrypsin, fungi protease and trypsin. It showed that these proteins could degrade the copolymer to some degree. The effects of pH, light and humidity on PHPAG were also investigated. The results indicated that it was stable under the experiment conditions.

Animals↗
PubMed1992

Isolation and amino acid sequence of a glutamic acid specific endopeptidase from Bacillus licheniformis.

An endopeptidase cleaving specifically at the carboxyl side of acidic amino acid residues, preferentially at glutamic acid, has been isolated from a commercial extract obtained by fermentation with Bacillus licheniformis. Using ion-exchange chromatography and affinity chromatography on bacitracin-Sepharose, it was possible, from 100 ml commercial extract, to isolate 100 mg homogeneous enzyme in a yield of 50%. It is the first description of a large-scale isolation of a Glu/Asp-specific enzyme. The preparation was essentially free of contaminating activities. The isolated enzyme consists of one peptide chain of 222 amino acid residues and has a calculated molecular mass of 23,589 Da. The determined amino acid sequence shows similarity to the Glu/Asp-specific enzymes previously isolated from Staphylococcus aureus V8, Actinomyces sp. and Streptomyces thermovulgaris. The substrate preference of the enzyme has been investigated. Although non-specific cleavages were observed after prolonged hydrolysis at high enzyme concentrations the enzyme appears to be essentially specific for Glu-Xaa and Asp-Xaa, with strong preference for the former. The isolated enzyme exhibits a bell-shaped pH/activity profile with an optimum at pH 7.5-8.0. The activity is adversely affected by high ionic strength and beneficially affected by the inclusion of calcium ions in the assay medium. The enzyme is completely inhibited by diisopropylfluorophosphate, suggesting that it is a serine endopeptidase. It is partially inhibited by EDTA.

Amino Acid Sequence↗
PubMedDate not supplied

Selective inhibition of homocysteine-induced seizures by glutamic acid diethyl ester and other glutamate esters.

Homocysteine thiolactone causes convulsions when administered to animals, and has recently been reported to have excitatory effects on neurons in the central nervous system. Glutamic acid diethyl ester (GDEE) has previously been found to be an effective antagonist of the central excitation induced by homocysteine and is thought to be a selective antagonist of the quisqualate-sensitive excitatory amino-acid-receptor site. If an interaction of homocysteine with the quisqualate-sensitive receptor site is responsible for its convulsive properties, GDEE might also block the induction of seizures by homocysteine. GDEE in a dosage of 4 mmol/kg almost completely blocked homocysteine-induced seizures in mice; smaller dosages had no effect or only slight inhibitory effects. Glutamic acid dimethyl ester (GDME) and glutamic acid gamma-methyl ester (GMME) also partially blocked homocysteine-induced seizures, but monosodium glutamate and glutamic acid gamma-monoethyl ester (GMEE) had only a slight effect. None of the glutamate esters inhibited seizures induced by pentylenetetrazole. It is therefore suggested that certain types of seizures involve the quisqualic acid excitatory amino-acid-receptor site. Homocysteine-induced seizures may serve as a model of seizures of this type, and GDEE, GDME, and GMME may be effective antagonists of such seizures.

Animals↗
PubMed1987

Active site of Pseudomonas aeruginosa exotoxin A. Glutamic acid 553 is photolabeled by NAD and shows functional homology with glutamic acid 148 of diphtheria toxin.

Photoaffinity labeling with native NAD, a method employed earlier with diphtheria toxin (DT), was used to identify an active site residue of Pseudomonas aeruginosa exotoxin A (ETA). An enzymically active fragment (Mr 27,000), derived by partial digestion of ETA with thermolysin, was irradiated with ultraviolet light (254 nm) in the presence of various radiolabeled preparations of NAD. Label from the nicotinamide moiety was efficiently transferred to the protein (maximally 0.79 mol/mol), and the label was exclusively located at position 553. This position, like that photolabeled in DT (position 148), corresponds to glutamic acid in the native protein. Chromatographically identical photo-products were generated at these positions in the two toxins. Glu-553 lies in a cleft in domain III that is believed to represent the active site of ETA, and other evidence supports the notion that Glu-553 of ETA and Glu-148 of DT are directly involved in catalysis. When Glu-553 of ETA was aligned with Glu-148 of DT, we found similarities of local primary structure not detected earlier. These results suggest that the catalytically active domains of ETA and DT may be evolutionarily related, and they provide information that should prove useful for preparing vaccines against ETA by recombinant DNA methods.

ADP Ribose Transferases↗
PubMed1999

Role of nitric oxide on GABA, glutamic acid, activities of GABA-T and GAD in rat brain cerebral cortex.

The results of the present study clearly shows that a correlation exists between nitric oxide (NO) and gamma-aminobutyric acid transaminase (GABAT-T) activity as well as gamma-aminobutyric acid (GABA), glutamic acid and the activity of glutamic acid decarboxylase (GAD). Supporting of this 10 min after the administration of L-Arginine (L-Arg) increased GABA concentration and diminished the activity of GABA-T. There was no change in GAD activity and glutamic acid level. Administration of convulsion inducing agent Picrotoxin (PCT) decreased the NO concentration in the brain and enhanced the activity of GABA-T, and the fact that the NOS inhibitor (N(G)-nitro-L-Arg methyl ester (L-NAME) diminished the activity of NOS and increased the activity of GABA-T provide another support for the involvement of NO on GABA-T activity. The present study clearly showed that high concentrations of NO in the brain suppresses the activity of GABA-T.

4-Aminobutyrate Transaminase↗
PubMed1983

Glutamic acid decarboxylase in cerebrospinal fluid in infancy and childhood Part II. Glutamic acid decarboxylase activity in cerebrospinal fluid of children with neurological diseases.

Glutamic acid decarboxylase (GAD) activity in cerebrospinal fluid (CSF) was determined in 53 patients with neurological diseases as follows: Epilepsy (n:17), febrile convulsions (n:3), meningoencephalitis (n:17), encephalopathies (n:10), CNS leukemia (n:3), congenital hydrocephalus (n:2) and pseudoileus neonatorum (n:1). Compared with the mean normal value (5.2 +/- 2.5 pmol CO2 formed/hr/ml) reported in Part I, a significant increase of GAD activity in CSF was demonstrated in patients with uncontrolled epileptic seizures (11.4 +/- 3.9 pmol CO2 formed/hr/ml), febrile convulsions (13.5 +/- 8.7), viral meningitis with or without encephalitis (20.3 +/- 13.6), encephalopathies (30.0 +/- 25.9), CNS leukemia (11.1 +/- 5.0), congenital hydrocephalus (20.5 +/- 7.3) and pseudoileus neonatorum (28.6). Markedly high GAD activity was found in patients with CNS leukemia several days after intrathecal injection of methotrexate (39.8 +/- 18.0). On the other hand, significantly low GAD activity was shown in patients with bacterial meningitis or brain abscess (1.3 +/- 1.2). This suggests that some bacterial factors may be inhibitory toward GAD activity in CSF. High GAD activity in CSF may be useful as an indicator of aseptic brain dysfunction, although it was not always correlated with the severity of symptoms.

Adolescent↗
PubMed1987

Engineering of the active site of human lysozyme: conversion of aspartic acid 53 to glutamic acid and tyrosine 63 to tryptophan or phenylalanine.

Three human lysozymes containing a mutation either at Asp-53 to Glu or at Tyr-63 to Trp or Phe were synthesized and examined for their immunological and enzymatical activities in comparison with the native one. All mutants were immunologically indistinguishable from native human lysozyme. The [Trp63] and [Phe63] mutants catalysed the hydrolysis of Micrococcus lysodeikticus cell wall and glycol chitin effectively, while the [Glu53] mutant displayed very low activity toward M. lysodeikticus cells and no detectable activity toward glycol chitin.

Amino Acid Sequence↗