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Design, synthesis, and biological activities of classical N-[4-[2-(2-amino-4-ethylpyrrolo[2,3-d]pyrimidin-5-yl)ethyl]benzoyl]-l-glutamic acid and its 6-methyl derivative as potential dual inhibitors of thymidylate synthase and dihydrofolate reductase and as potential antitumor agents.

Two novel analogues, N-[2-amino-4-ethyl[(pyrrolo[2,3-d]pyrimidin-5-yl)ethyl]benzoyl]-l-glutamic acid (2) and N-[2-amino-4-ethyl-6-methyl[(pyrrolo[2,3-d]pyrimidin-5-yl)ethyl]benzoyl]-l-glutamic acid (4), were designed and synthesized as potent dual inhibitors of thymidylate synthase (TS) and dihydrofolate reductase (DHFR) and as antitumor agents. Compound 2 had inhibitory potency against human DHFR similar to N-[4-[2-(amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5-yl)ethyl]benzoyl]-L-glutamic acid (LY231514) and 1, whereas 4 was inactive against human DHFR. Both 2 and 4 were more potent than LY231514 against E. coliTS. Against human TS, 2 was 7-fold less potent than LY231514 and 4 showed similar inhibitory activity as LY231514. In contrast to 2, which was an efficient substrate of human folypolyglutamate synthetase (FPGS), 4 was a poor substrate of FPGS. Compound 2 showed GI50 values in the nanomolar range against more than 18 human tumor cell lines in the standard NCI preclinical in vitro screen.

Antineoplastic Agents↗

Clinical and biochemical characteristics of nonobese type 2 diabetic patients with glutamic acid decarboxylase antibody in Korea.

We evaluated the prevalence of glutamic acid decarboxylase autoantibody (GADA) in nonobese patients with type 2 diabetes mellitus in Korea and investigated the characteristics of GADA-positive and GADA-negative patients. Two years later, we assessed the progression of beta-cell function in these patients. Of the 647 nonobese patients with type 2 diabetes mellitus enrolled in the study, 10.1% was positive for GADA. Glutamic acid decarboxylase antibody-positive patients had lower fasting and stimulated C-peptide levels compared with GADA-negative patients (1.70 +/- 0.72 vs 1.24 +/- 0.59 microg/L, P < .001; 2.59 +/- 1.51 vs 1.99 +/- 0.82 microg/L, P < .001). Patients treated with insulin had lower fasting and stimulated C-peptide levels than those not treated (1.13 +/- 0.52 vs 1.66 +/- 0.73 microg/L, P = .002; 1.85 +/- 0.69 vs 2.49 +/- 0.91 microg/L, P = .004) and had higher titers of GADA (30.5 +/- 7.3 vs 6.0 +/- 4.8 U/mL, P < .001). In terms of progression of beta-cell function, fasting and stimulated C-peptide levels were significantly lower in GADA-positive patients after 2 years (from 1.24 +/- 0.59 to 0.95 +/- 0.54 microg/L, P = .004; from 1.99 +/- 0.82 to 1.61 +/- 0.77 microg/L, P = .007), whereas no such difference was observed in the GADA-negative patients. We demonstrate that a significant proportion of Korean patients may be positive for GADA; this is consistent with studies of white subjects, although disagrees with previous reports on Korean subjects. By assessing the presence of GADA in Korean type 2 diabetic patients, we are able to predict their course of beta-cell function and identify in advance those who are likely to require insulin treatment.

Adult↗

Specific binding of L-[3H]-glutamic acid to rat substantia nigra synaptic membranes.

The specific binding of L-[3H]-glutamic acid (GLU) was investigated in synaptic membranes from rat substantia nigra. L-[3H]-GLU binding to the membrane preparations occurred in a reversible and saturable way. The specific binding was stimulated by the presence of CaCl2 and was reduced by freezing and thawing the membranes. Scatchard analysis of the saturation isotherms yielded a non-linear plot suggesting that the binding reaction does not occur through a simple bimolecular association. Assuming non-interacting binding sites, a high (KD1, 139 nM; Bmax1, 3.5 pmoles/mg protein) and a low (KD2, 667 nM; Bmax2, 15.1 pmoles/mg protein) affinity L-[3H]-GLU binding site were obtained. The kinetics of dissociation of bound L-[3H]-GLU was biphasic; the respective dissociation rate constant (k-1) being 0.20 min-1 and 0.013 min-1. A series of amino acid receptor agonists and antagonists were tested as inhibitors of L-[3H]-GLU specific binding. Quisqualic acid, L-GLU and D-alpha-aminoadipate (D-alpha-AA) were the most potent inhibitors. DL-2-amino-4-phosphonobutyrate (APB), N-Methyl-D-aspartate (NMDA) and D-GLU were moderate inhibitors, whereas diaminopimelic acid (DAPA) and glutamate diethyl ester (GDEE) exhibited the lowest relative potency. Kainic acid (KA), gamma-aminobutyric acid (GABA) and bicuculline were not able to modify at any concentration used the specific binding of L-[3H]-GLU. These data demonstrate the presence of specific GLU binding sites in synaptic structures at substantia nigra level and support the idea that excitatory amino acids may play a role in synaptic transmission in this brain region.

2-Aminoadipic Acid↗

Association between nonsyndromic cleft lip with or without cleft palate and the glutamic acid decarboxylase 67 gene in the Japanese population.

Nonsyndromic cleft lip with or without cleft palate (NSCLP) is one of the most common craniofacial malformations. Both genetic and environmental factors are involved in the pathogenesis. In addition to its role as an inhibitory neurotransmitter, gamma-aminobutyric acid (GABA) synthesized by glutamic acid decarboxylase (GAD) is presumed to play a role in normal embryonic, especially facial, development. This notion has been substantiated by the fact that Gad67 knockout mice have been shown to have cleft palate. We hypothesized that GAD67 may be involved in the development of NSCLP and investigated the possible association between the GAD67 gene (GAD67) and NSCLP in Japanese patients. We screened 50 probands for single nucleotide polymorphisms (SNPs) in GAD67 using denaturing high performance liquid chromatography (DHPLC) and found seven SNPs. Since two SNPs showed complete linkage disequilibrium (LD) to the other SNPs, we constructed a 5-locus haplotype of GAD67. The frequency distribution of the haplotype differed between NSCLP patients and controls (P = 0.0028). The frequency of -445A, -292A, -147G, 111C, and IVS9-39T haplotype in the NSCLP patients was significantly lower than that in controls (P = 0.00098). In a transmission disequilibrium test (TDT) in 99 parent-offspring trios, we found -445C, -292C, -147G, 111C, and IVS9-39C haplotype was preferentially transmitted to the patients with cleft lip and palate (P = 0.0077). Our data suggest that GAD67 is involved in the pathogenesis of NSCLP in the Japanese population.

Asian People↗

The hydrogen-bonding network in (+)-N-tosyl-L-glutamic acid.

The asymmetric unit of the alpha polymorph of (+)-N-tosyl-L-glutamic acid, C12H15NO6S, contains two independent molecules which differ in conformation. The carboxylic acid groups form an infinite zigzag chain with characteristic R(2)(2)(8) rings running along the b axis. Intermolecular N-H...O and C-H...O contacts mediate the formation of a three-dimensional supramolecular structure described by R(4)(3)(22), R(6)(6)(44) and R(8)(8)(54) graph-set descriptors. Comparison of the extended structure with that of N-(benzenesulfonyl)glutamic acid shows that a subtle difference in the periphery of the molecule, i.e. the replacement of the toluyl group with a phenyl group, can be accompanied by dramatic changes in molecular assembly.

Crystallography, X-Ray↗

Structural analogues of L-glutamic Acid gamma-(4-hydroxyanilide) and gamma-(3,4-dihydroxyanilde) as potential agents against melanoma.

Nine heretofore unknown mono- and dihydroxyanilide analogues of the cytotoxic mushroom metabolites L-glutamic acid gamma-(4-hydroxyanilide) (1) and L-glutamic acid gamma-(3,4-dihydroxyanilide) (3, agaridoxin) were synthesized and tested as inhibitors of the growth of B16 mouse melanoma cells in culture. The naturally occurring anilides 1 and 3 had ID50 values of 0.10 and 0.27 mM, respectively. The analogue of 1 in which the gamma-L-glutamyl moiety was replaced by beta-L-aspartyl showed only a threefold decrease in activity, whereas attachment of the phenolic OH group to the meta instead of the para position resulted in a tenfold decrease. Other structural modifications, such as O-methylation or deletion of the carboxyl or amino group in the side chain, led to compounds of still lower activity (ID50 greater than 1.0 mM). The only analogue in the series with more activity than either 1 or 3 against B16 cells was L-glutamic acid gamma-(2,5-dihydroxyanilide) (14), which had an ID50 value of 0.051 mM. These data suggest that the gamma-L-glutamyl side chain in 1 or 3 plays a significant role in the biological action of these compounds, though some flexibility appears to exist insofar as the positioning of OH groups on the aromatic ring is concerned.

Anilides↗

A determinant of resistance of Neisseria gonorrhoeae to killing by human phagocytes: an outer membrane lipoprotein of about 20 kDa with a high content of glutamic acid.

A protein of about 20 kDa was extracted by sodium cholate (1%, w/v) from outer membranes of a strain of Neisseria gonorrhoeae, BS4 (agar), which is resistant to killing by human phagocytes. When the protein was purified by repeated fractionation on Sephadex G75, contamination with other outer-membrane proteins and lipopolysaccharide was negligible. The protein contained a full complement of amino acids, with high levels of glutamic acid. Carbohydrate, detected by the anthrone method and by sugar and hexosamine analysis, was present, but at very low levels. There was a significant content of fatty acids (about 5.7% of the protein), indicating a lipoprotein. The 20 kDa lipoprotein: (1) neutralized the ability of antiserum against whole organisms of BS4 (agar) to reduce the resistance of this strain to phagocyte killing; (2) evoked in mice an antiserum which reduced this resistance and immunoblotted only with 20 kDa lipoprotein in the cholate extract of outer membranes; and (3) promoted resistance to intracellular killing of an otherwise phagocyte susceptible gonococcal strain (BSSH). This is strong evidence that it is a determinant of gonococcal resistance to phagocyte killing.

Bacterial Outer Membrane Proteins↗

Determination of glutamic acid and gamma-aminobutyric acid in Ringer's solution without desalination at the femtomole level by gas chromatography chemical ionization mass spectrometry.

For the quantification of glutamic acid in Ringer's solution, pentafluoropropionic methyl ester was the most sensitive derivative. The detectable concentration was 0.01 microM glutamic acid in Ringer's solution; the amount of the preparation was 1 pmol and the injection into a gas chromatograph mass spectrometer was 10 fmol. For the quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was quantification of gamma-aminobutyric acid in Ringer's solution, the trifluoroacetal-hexafluoropropionyl ester was detectable at a concentration of 0.01 microM. Ringer's salts facilitated acylation in the order heptafluorobutyric anhydride greater than pentafluoropropionic anhydride greater than trifluoroacetic anhydride. The effect depended on esterification of carboxy groups in the order methyl ester greater than hexafluoropropionyl ester greater than butyl ester. Sodium carbonate, sodium acetate and sodium citrate also facilitated acylation with pentafluoroproionic anhydride, while sodium phosphate inhibited the acylation and sodium sulfate inhibited it slightly. The pentafluoropropionic methyl ester of glutamic acid was stable for up to 10 days, when it was dissolved in acetone and stored at -18 degrees C.

Gas Chromatography-Mass Spectrometry↗

Mice lacking the 65 kDa isoform of glutamic acid decarboxylase (GAD65) maintain normal levels of GAD67 and GABA in their brains but are susceptible to seizures.

The gene encoding of the 65 kDa isoform of the gamma-aminobutyric acid (GABA)-synthesizing enzyme, glutamic acid decarboxylase (GAD), GAD65, was targeted in mice by homologous recombination. Viable GAD65 -/- mice were obtained with the expected mendelian frequency and displayed no gross morphological defects. Despite the complete loss of GAD65 mRNA and protein in a homozygous mutant, there was no difference in GABA content in the brains of GAD65 +/+, +/-, and -/- mice. As for the other 67 kDa isoform (GAD67), the levels of mRNA and protein were largely unchanged by the GAD65 mutation. General behavior, including locomotor activity and performance in the Morris water maze task, appeared normal, but seizures were more easily induced by picrotoxin and pentylenetetrazol: the latencies to seizures induced by picrotoxin were shorter and the dose of pentylenetetrazol required for induction of seizures was lower.

Animals↗

Hb Catonsville (glutamic acid inserted between Pro-37(C2)alpha and Thr-38(C3)alpha). Nonallelic gene conversion in the globin system?

Hb Catonsville is an unstable variant in which glutamic acid is inserted into the alpha-globin chain between Pro-37(C2) and Thr-38(C3). The peptide sequence data are consistent with the DNA sequence of the polymerase chain reaction-amplified fragment of the variant globin gene, which shows the insertion of the triplet codon--GAA--into the mutant alpha-globin gene. In the normal alpha-globin gene cluster the codon for glutamic acid is GAG rather than GAA. Thus, there are two features unique to Hb Catonsville, one the insertion of a single residue into the interior of the alpha-globin chain, and two the presence of the alternate codon for glutamic acid. The experimental evidence suggests that Hb Catonsville may be an example of nonhomologous nonallelic gene conversion, an observation not previously reported in this gene family. The mutation occurs in the critical alpha 1 beta 2 interface of the hemoglobin tetramer and leads to a variant with high oxygen affinity, a reduced cooperativity, and Bohr effect.

Alleles↗

[Anti-ammonemic activity of the gamma-ethyl ester of glutamic acid. Controlled clinical study].

A controlled clinical trial was made of the anti-ammoniaemic properties of gamma-ethylester glutamic acid, arginine and placebo in a series of 45 patients with hepatic insufficiency characterized by hyperammonemia (excluding cases of pre-coma and coma) randomly assigned to three groups for treatment with: gamma-ethylester of glutamic acid (25 g), l-arginine (25 g) and physiological solution in identical 500 ml bottles. Various parameters were controlled. The results obtained were assessed with different statistical techniques, depending on the parameter concerned and the aims of the trial. Blood ammoniaemia was significantly decreased by both-ethylester of glutamic acid and arginine though the former was more effective quantitatively and in terms of time. SGOT and BSF values also followed the same pattern.

Ammonia↗

[Inhibition of glutamine synthetase activity by biologically active derivatives of glutamic acid].

The inhibition of activity of glutamine synthetase from Chlorella and porcine brain by 4-hydroxy-D-4-fluoro-D,L- and 4-amino-D,L-glutamic acids diastereoisomers was studied. Each compound was shown to exert the same inhibiting effect on glutamine synthetase from both sources. In case of threo-4-hydroxy-D-glutamic acid the inhibition of the Chlorella enzyme was of a competitive and of a completely mixed type. The enzyme inhibition by 4-fluoro-D, L-glutamic acids seemed to be of a completely non-competitive type. The Ki values for all inhibition reactions were determined. A comparison of biochemical parameters and biological activity revealed that the most effective inhibitors of the enzyme exert a most potent antitumour and antiviral action.

Animals↗

Assay and properties of glutamic acid decarboxylase in homogenates of crayfish nervous tissue.

The activity of glutamic acid decarboxylase (GAD) was measured in homogenates of crayfish nervous tissue. Radioactive GABA and CO2 were formed from radioactive glutamic acid in approximately equimolar amounts. Product formation was linear for 9.5 hr at 11-32 degrees C with about 1-30 micrograms homogenate protein. Enzyme activity remained high at pH 7-10 but declined steeply above pH 10.5 and below pH 7. Enzyme activity was stimulated by pyridoxal phosphate, 2-mercaptoethanol, and potassium phosphate; at higher than optimal concentrations of each the activity was reduced. Sodium phosphate altered the stimulatory effect of potassium phosphate. Crayfish GAD behaves like a typical neural GAD but is distinguishable biochemically from GAD of other species.

Animals↗

Immunocytochemical localization of glutamic acid decarboxylase in physiologically identified interneurons of hamster spinal laminae III-V.

Neurons in Rexed's laminae III-V of an isolated spinal cord-skin patch preparation from hamsters were recorded in whole-cell mode and stained intracellularly with biocytin. Evidence of inhibitory synaptic function was obtained via post-hoc immunofluorescent labeling with a monoclonal antibody directed against an axon terminal isoform of brain glutamic acid decarboxylase. For a subset of neurons, examination with laser scanning confocal microscopy revealed punctate accumulations of glutamic acid decarboxylase immunoreactivity within axon enlargements (1-3 microm diameter), as imaged in single optical sections and confirmed by subsequent optical scans in the orthogonal plane. Axons of glutamic acid decarboxylase-immunoreactive neurons were found to exhibit dense local terminations overlapping the soma and dendrites or bifurcated into lengthy rostrocaudal daughter branches ventral to the cell body. The degree and uniformity of immunolabeling in axonal enlargements varied considerably, even amongst boutons belonging to the same cell. Glutamic acid decarboxylase-positive neurons received input from myelinated (A) afferent fibers and responded to natural stimuli appropriate for activating responses in low threshold mechanoreceptors. These results provide evidence that two different populations of GABAergic inhibitory interneurons are involved in local and intersegmental circuits that mediate integration of mechanosensory information in the deep spinal dorsal horn.

Animals↗

[Selective sensitivity of synaptosomal cyclases to glutamic acid].

Electron cytochemical studies have been made of the effect of various concentrations of the glutamic acid on localisation of adenylate and guanylate cyclases in synaptosomes from the brain cortex of rats. It was found that the glutamic acid (10(-3) M) stimulates the activity of intrasynaptosomal adenylate cyclase, but does not affect postsynaptic pool of the enzyme. The effect of glutamate on guanylate cyclase results in the increase of the frequency of the reaction both in synaptosomal and postsynaptic membranes. It is suggested that in the conduction of glutamate signal, guanylate cyclase--cGMP, but not adenylate cyclase--cAMP, system may be involved, although activation of intrasynaptosomal adenylate cyclase indicates its participation in presynaptic processes.

Adenylyl Cyclases↗

Possible coexistence of amino acid (gamma-aminobutyric acid), amine (dopamine) and peptide (substance P); neurons containing immunoreactivities for glutamic acid decarboxylase, tyrosine hydroxylase and substance P in the hamster main olfactory bulb.

The coexistence of immunoreactivities for glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH) and substance P (SP) was revealed in the hamster main olfactory bulb, using the peroxidase-antiperoxidase immunohistochemical method. Adjacent 40 micron thick Vibratome sections were incubated in different antisera and those cells which were bisected by the plane of sectioning were identified at the paired surfaces of two consecutive sections. The coexistence of the immunoreactivities for 1) TH and GAD, 2) TH and SP and 3) GAD and SP in the same cells could thus be determined by observing the immunoreactivity of the two halves of the cell incubated in two different antisera. About 70% of TH-like immunoreactive (TH-LI) neurons in the periglomerular region also contained GAD-like immunoreactivity, whereas about 45% of GAD-LI ones were also TH-like immunoreactive. Furthermore, almost all (more than 95%) of SP-LI neurons contained both GAD-like and TH-like immunoreactivities. These observations indicate that in the periglomerular region of the hamster main olfactory bulb, some neurons (about 9% of all neurons containing TH-like and/or GAD-like immunoreactivities) may contain three different categories of neuroactive substances, that is, amino acid (GABA), amine (dopamine) and peptide (SP).

Animals↗

Inhibitory effects of GABA, L-glutamic acid and nicotine on the potassium-evoked release of substance P in substantia nigra slices of the rat.

Rat substantia nigra slices were superfused with a physiological medium containing a diluted substance P (SP) antiserum, bacitracin and serum albumin to measure SP released in superfusates. As shown by measuring the degradation of a SP-labelled derivative incubated with cerebellar slices, this medium prevented the enzymatic inactivation of SP. Potassium (K+, 50 mM) and veratridine (5 X 10(-5) M) stimulated SP release and these effects were respectively prevented in absence of calcium and in presence of tetrodotoxin (5 X 10(-7) M). GABA (5 X 10(-5) M), nicotine (10(-6) M) and L-glutamic acid (5 X 10(-5) M) reduced the K+ (50 mM)-evoked release of SP. In contrast, glycine (5 X 10(-5) M), oxotremorine (5 X 10(-5) M), D-glutamic acid (5 X 10(-5) M) and serotonin (5 X 10(-5) M) were without effect. Pempidine (10(-5) M) prevented the inhibitory effect of nicotine (10(-6) M) on the K+-evoked release of SP. Glutamic acid diethyl ester (10(-4) M) completely abolished the L-glutamic acid-induced inhibition of the K+-evoked release of SP. Picrotoxin (5 X 10(-5) M) did not influence the L-glutamic acid inhibitory effect excluding the intervention of GABAergic mechanisms.

Animals↗

Immunocytochemical localization of glutamic acid decarboxylase in the dorsal lateral vestibular nucleus: evidence for an intrinsic and extrinsic GABAergic innervation.

Immunocytochemical methods were used to localize the gamma-aminobutyric acid (GABA) synthesizing enzyme glutamic acid decarboxylase (GAD) in normal and partially deafferented dorsal lateral vestibular nucleus (dLVN) of the rat. Normal dLVN exhibited more intense staining than the ventral part of the nucleus (vLVN), and this was mainly due to more numerous GAD+ axon terminals surrounding dLVN somata and within neuropil. Small GAD+ somata were also present. Electron microscopy suggested the existence of two types of GAD+ synaptic terminals. The major type conformed to descriptions of Purkinje cell terminals, whereas the minor type did not. Ablation of the anterior cerebellar vermis resulted in a 73% reduction in the number of GAD+ terminals, the percentage decrease being greater around neuronal somata (83%) than within neuropil (70%). The presence of GAD+ somata within the nucleus and the persistence of some GAD+ terminals after extensive lesions of the Purkinje cell afferents suggest that both extrinsic and intrinsic GABAergic neurons may contribute to information processing within the dLVN.

Afferent Pathways↗