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Identity of the heme-not-containing protein in bovine heart cytochrome c1 preparation with the protein mediating c1-c complex formation--a protein with high glutamic acid content.

A heme-not-containing protein was isolated from cytochrome c1 preparation by gel filtration after carboxymethylation and citraconylation. The amino acid sequence of this protein was determined by the analysis of tryptic and chymotryptic peptides as well as by solid-phase sequence analysis. It consisted of 78 amino acid residues and the molecular weight was calculated to be 9,175. This protein contained a high proportion of glutamic acid and glutamine (27% of the total residues) but no methionine, isoleucine, tyrosine, and tryptophan. The most notable feature was an acidic cluster of 8 consecutive glutamic acid residues near the amino(N)-terminus). The secondary structure was predicted to have a high proportion of helical content. The amino acid composition and N-terminal sequence of a protein independently prepared from bovine heart mitochondria, which is essential to the formation of the cytochrome c1-c complex, suggested that this colorless factor and the present heme-not-containing protein are identical. Evidence shows that another protein, called the non-heme protein, isolated from "two-band" cytochrome c1 preparation is also the same protein as that presented in this paper.

Amino Acid Sequence↗

The presence of glutamic acid at positions 71 or 74 in pocket 4 of the HLA-DRbeta1 chain is associated with the clinical course of multiple sclerosis.

BACKGROUND: Primary progressive multiple sclerosis (PP-MS) differs from relapsing-remitting or secondary progressive MS (RR/SP-MS) in ways suggesting differences in the pathogenic pathways. Susceptibility to both PP-MS and RR/SP-MS is linked to carriage of the HLA molecule DRB1*1501. Several serologically defined HLA-DR groups (DR1, DR4, DR6, and DR9) occur less often in RR/SP-MS than in controls. Some or all of the HLA-DR molecules encoded by alleles in these serologically defined groups have a negatively charged glutamic acid at residue 71 or 74 of the beta1 chain (beta1(71)/beta1(74)). Residues at these positions are important in the formation of pocket 4 in the antigen binding site of the HLA-DR molecule. OBJECTIVES: To investigate whether the presence of alleles encoding HLA-DR molecules containing glutamic acid at beta1(71)/beta1(74) correlates with the course of MS. METHODS: HLA-DR and HLA-DQ alleles and genotypes were analysed in 121 MS patients (50 with PP-MS) and 109 controls by molecular typing. RESULTS: Alleles encoding HLA-DR molecules containing a glutamic acid at beta1(71)/beta1(74) occurred less often in patients with RR/SP-MS than in those with PP-MS or controls. In subjects not carrying the DRB1*1501 allele, a much higher proportion of PP-MS patients carried alleles encoding HLA-DR molecules containing a glutamic acid at beta1(71)/beta1(74) than did RR/SP-MS patients or controls. CONCLUSIONS: The amino acid residues involved in determining the shape and charge of pocket 4 of the HLA-DR beta1 chain could influence the clinical course of MS by determining protection against RR/SP-MS or susceptibility to the development of PP-MS.

Alleles↗

L-glutamic acid decarboxylase: a new type in glial cells and human brain gliomas.

Human glial cells grown in culture and gliomas and white matter contain an l-glutamic acid decarboxylase which is stimulated markedly by carbonyl-trapping agents. In contrast, L-glutamic acid decarboxylase activity of human cerebral gray matter is strongly inhibited by carbonyl-trapping agents. These results suggest a glial localization of the new type of l-glutamic acid decarboxylase.

Aminobutyrates↗

Uptake and utilization of glutamic acid by Cryptococcus albidus.

Cryptococcus albidus utilizes glutamate as a sole carbon source. The kinetics of uptake of this amino acid were studied. l-Glutamic acid was taken up by two saturable systems: a high affinity system with a Michaelis constant (K(m)) of 1.15 x 10(-5) M and a V(max) of 0.049 mumol per mg per h and a low affinity system with a K(m) of 2.5 x 10(-3) M and a V(max) of 3.61 mumol per mg per h. Both systems possessed characteristics of active transport which were dependent on temperature and pH and which required metabolic energy. Uptake was inhibited at 37 C but the temperature-sensitive step was reversible. Chemical fractionation of cells with 5% trichloroacetic acid showed that glutamic acid initially entered a soluble pool which decreased after 1 h as the amino acid was incorporated into the protein and nucleic acid fractions of the yeast. Some of the glutamate was completely oxidized and could be recovered as (14)CO(2). Therefore, the amino acid was also used as an energy source.

Amino Acids↗

Induction of tolerance to nucleic acid determinants by administration of a complex of nucleoside D-glutamic acid and D-lysine (D-GL).

The administration of nucleosides coupled covalently to the copolymer of D-glutamic acid and D-lysine (D-GL) or to its stereoisomer, L-GL, induces a state of nucleoside (NUC)-specific tolerance in inbred SJL and BALB/c mice, irrespective of their immune status at the time of treatment. Such tolerance is characterized by the inability of treated animals to mount either primary or secondary, intact or adoptive, anti-NUC antibody responses following immunization with a highly immunogenic conjugate of NUC-Keyhole limpet hemocyanin. These observations have potential therapeutic importance in autoimmune processes involving anti-DNA antibody production.

Animals↗

[The glutamic acid decarboxylase disc test. An approach for the simplification and speeding up of E. coli detection].

Although E. coli is certainly one of the best known and most widely examined bacterial species only few of their characters and properties were found suitable for the distinction of this species from other species especially from the coliform organisms. One of these rare characters is l-glutamic acid decarboxylase. The demonstration of the action of this enzyme, however, has hitherto been difficult and time consuming. A micro-method is described which permits the demonstration of l-glutamic acid decarboxylase--the glutamic acid decarboxylase disc test (gd-disc-test). The conditions and procedures required are described in detail. The validation of this test was done demonstrating in presence of gamma-aminobutyric acid by paper chromatography.

Chromatography, Paper↗

The selective inhibition of hippocampal glutamic acid decarboxylase in zinc-induced epileptic seizures.

The intracerebroventricular administration of Zn2+ (0.3 mumol/10 microliters) causes epileptic seizures characterized by running fits, jumping, vocalization, fasiculation of facial muscles, myoclonic movements of the limbs and tonic-clonic convulsions. These episodes are blocked or reversed by gamma-aminobutyric acid (0.4 mumol/10 microliters). When assayed under conditions where pyridoxal phosphate was not added, the activity of glutamic acid decarboxylase decreased significantly in hippocampus from 18.9 to 15.3 and 9.7 mumols 14CO2 formed/gram proteins/20 min, 15 and 30 min following administration of Zn2+. The inhibition of glutamic acid decarboxylase by Zn2+ was selective occurring only in hippocampus and not in the hypothalamus, amygdala, caudate or thalamus. The inhibition of glutamic acid decarboxylase was not due to a reduction in the concentration of endogenous pyridoxal phosphate which remained unaltered in hippocampus following Zn2+ administration.

Animals↗

Urinary excretion levels of carcinogenic glutamic acid pyrolysis products and their N-acetyl derivatives in humans.

UNLABELLED: The carcinogenic glutamic acid pyrolysis products 2-amino-6-methyldipyrido [1, 2-a: 3', 2'-d]imidazole (Glu-P-1) and 2-amino-dipyrido [1, 2-a: 3', 2'-d] imidazole (Glu-P-2), and their N-acetyl derivatives were measured in 24-h urine of individual subjects by high-performance liquid chromatography. These compounds were detected in all urine samples analyzed, although the contents varied widely among subjects. The mean levels of Glu-P-1, N-acetyl-Glu-P-1, Glu-P-2 and N-acetyl-Glu-P-2 in 24-h urine were 0.53, 0.41, 2.12 and 4.60 pmol, respectively. In vitro experiments revealed N-acetyltransferase activity with Glu-P-1 and Glu-P-2 in the cytosolic fractions from rat kidneys and human autopsy kidney specimens as well as those from liver specimens, suggesting that extrahepatic tissues may also play significant roles in the N-acetylation of these carcinogens. These results show that Glu-P-1 and Glu-P-2, after being partially N-acetylated in metabolic organs such as liver and kidney, are excreted into urine together with their N-acetyl derivatives. It is suggested that daily excretion of carcinogenic glutamic acid pyrolysis products and their N-acetyl derivatives into urine can be a suitable biological monitor for exposure to these carcinogens. ABBREVIATIONS: Glu-P-1, 2-amino-6-methyldipyrido [1, 2-a: 3', 2'-d] imidazole; Glu-P-2, 2-aminodipyrido [1, 2-a: 3', 2'-d] imidazole; N-acetyl-Glu-P-1, 2-acetylamino-6-methyldipyrido [1, 2-a: 3', 2'-d] imidazole; N-acetyl-Glu-P-2, 2-acetylaminodipyrido[1,2- a:3', 2'-d]imidazole; HPLC, high-performance liquid chromatography.

Acetylation↗

Glutamic acid decarboxylase and somatostatin immunoreactivities in rat visual cortex.

Antibodies to glutamic acid decarboxylase (GAD) and somatostatin (SS) were used to determine the laminar distribution and morphology of GAD- and SS-immunoreactive neurons and terminals in rat visual cortex. The present study demonstrates that GAD-immunoreactive neurons constitute several morphologically distinct subclasses of neurons in rat visual cortex. These subclasses of neurons can be distinguished by differences in soma size, soma shape, dendritic branching patterns, axonal arborizations, and location in the neuropil. GAD-immunoreactive neurons are found throughout all layers of visual cortex. They have nonpyramidal morphology and constitute roughly 15% of the total neuronal population. The laminar pattern of GAD-immunoreactive puncta is uneven, with a prominent band of terminals in layer IV. Numerous large GAD-positive puncta surround the somata and proximal dendrites of pyramidal cells in layers II, III, and V. SS-immunoreactive neurons constitute a less numerous and more restricted population of nonpyramidal neurons. Their somata are located mainly in layers II, III, V, and VI. Very few, if any, SS-immunoreactive neurons are found in layers I and IV. SS-immunoreactive terminals are arranged along vertical and diagonal collateral branches that have a beaded appearance. Finally, many neurons in the supra- and infragranular layers and in the white matter are immunoreactive to both glutamic acid decarboxylase and somatostatin. This coexistence of immunoreactivity to both GAD and SS may characterize a broad subclass of cortical nonpyramidal neurons.

Animals↗

Selective suppression of cerebellar GABAergic transmission by an autoantibody to glutamic acid decarboxylase.

Humoral immune response to glutamic acid decarboxylase (GAD) has been implicated in the pathogenesis of stiff-man syndrome and cerebellar ataxia, but the underlying pathomechanism is unclear. Using a whole-cell patch-clamp technique with rat cerebellar slices, we found that immunoglobulins present in the cerebrospinal fluid of an ataxic patient acted presynaptically to cause a selective suppression of GABAergic transmission. This synaptic depression was most likely elicited by an autoantibody to GAD.

Aged↗

Covalent modification of glassy carbon electrode with glutamic acid for simultaneous determination of uric acid and ascorbic acid.

A novel covalently modified glassy carbon electrode with glutamic acid has been fabricated via an electrochemical oxidation procedure and was applied to the catalytic oxidation of uric acid (UA) and ascorbic acid (AA), reducing the overpotentials by about 0.2 V and 0.3 V, respectively. Based on its strong catalytic function toward the oxidation of UA and AA, the modified electrode resolved the overlapping voltammetric response of UA and AA into two well-defined voltammetric peaks with both cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which can be used for the simultaneous determination of these species in a mixture. The catalytic peak current obtained from DPV was linearly dependent on the UA and AA concentration in the range 2 x 10(-6)-4 x 10(-4) mol L-1 and 1.0 x 10(-6)-4 x 10(-4) mol L-1 with correlation coefficients of 0.996 and 0.997, respectively. The detection limits (3 delta) for UA and AA were 1.1 x 10(-6) mol L-1 and 9.2 x 10(-7) mol L-1, respectively. The modified electrode shows good sensitivity, selectivity and stability, and has been applied to the determination of UA and AA simultaneously in human urine samples with satisfactory results.

Ascorbic Acid↗

Limitations of the poly(glutamic acid) reconstitution method in the reassembly of mono- and dinucleosomes.

Reconstitution of mononucleosomes and dinucleosomes at physiological ionic strength by means of poly(glutamic acid) is not efficient at physiological histone octamer:DNA ratios, unlike that with the salt dialysis method. The shorter the DNA is, the less transfer of octamers from poly(glutamic acid) to DNA occurs. By increasing the octamer:DNA ratio it is possible to involve all the DNA in the assembly, but for DNA longer than core particle length, nucleoprotein particles containing extra histones are concomitantly generated. Except for core particle and chromatosome lengths of DNA reassembled at 0.6:1 or 1:1 octamer:DNA ratio (and thus with low yield), reconstituted nucleoprotein particles proved to be different from native nucleosomes by their insolubility upon isolation. In the aggregates, DNA ends seemed to be sufficiently loose to allow exonuclease III digestion up to a certain limit. This resulted in patterns that for some cloned DNA fragments could give the impression, without knowledge of the above, of resulting from a unique octamer position. In view of the small range of length of DNA and the low yield of faithful reconstitution, the assembly method using poly(glutamic acid) is only of limited use in mono- or dinucleosome reconstitution experiments, at least in our hands.

Animals↗

High serum glutamic acid levels in patients with carcinoma of the pancreas.

High levels of glutamic acid and normal levels of glutamine were found in the blood of all but one of ten patients with carcinoma of the pancreas. No changes of the concentration in blood of these two amino acids were observed in 49 patients suffering from several diseases including malignant tumours. Although the mechanism of the rise of serum glutamic acid is difficult to explain at present, it may have some diagnostic value.

Female↗

Glutamic acid 327 in the sheep alpha 1 isoform of Na+,K(+)-ATPase stabilizes a K(+)-induced conformational change.

By combining the tools of site-directed mutagenesis and [3H]ouabain binding, the functional role of glutamic acid 327 in the fourth transmembrane domain of the sheep alpha 1 isoform of Na+,K(+)-ATPase was examined with respect to its interactions with ouabain, Na+,K+,Mg2+, and inorganic phosphate. Using site-directed mutagenesis, this glutamic acid was substituted with alanine, aspartic acid, glutamine, and leucine. The mutant proteins were constructed in a sheep alpha 1 protein background such that [3H]ouabain binding could be utilized as a highly specific probe of the exogenous protein expressed in NIH 3T3 cells. Na+ competition of [3H]ouabain binding to the mutant forms of Na+,K(+)-ATPase revealed only slight alterations in their affinities for Na+ and in their abilities to undergo Na(+)-induced conformational changes which inhibit ouabain binding. In contrast, K+ competition of [3H]ouabain binding to all four mutant forms of Na+,K(+)-ATPase displayed severely altered interactions between these proteins and K+. Interestingly, [3H]ouabain binding to the mutant E327Q was not inhibited by the presence of K+. This mutant was previously reported to be functionally able to support cation transport with a 5-fold reduced K0.5 for K(+)-dependent ATPase activity (Jewell-Motz, E. A., and Lingrel, J.B. (1993) Biochemistry 32, 13523-13530; Vilsen, B. (1993) Biochemistry 32, 13340-13349). Thus, it appears that this glutamic acid in the fourth transmembrane domain may be important for stabilizing a K(+)-induced conformation within the catalytic cycle of Na+,K(+)-ATPase that is not rate-limiting in the overall ATPase cycle but that displays a greatly reduced affinity for ouabain.

3T3 Cells↗

Protein engineering of cytochrome c by semisynthesis: substitutions at glutamic acid 66.

We have used protein semisynthesis to prepare four analogues of horse cytochrome c, in which the glutamic acid residue at position 66 has been removed and replaced by norvaline, glutamine, lysine and, as a methodological control, glutamic acid. This residue is quite strongly conserved in mitochondrial cytochrome c, and forms part of a cluster of acidic residues that occurs in all cytochromes c but whose function is obscure. Comparative studies of the physical and biochemical properties of the analogues have now disclosed two specific roles for Glu66 in the protein. It contributes significantly to the stabilization of the active conformation of the protein, probably by salt bridge formation, and it appears to participate in the redox-state-dependent ATP-binding site of cytochrome c. Our results also support two general views of the role of surface charged residues in cytochrome c, namely that their disposition influences both redox potential, through the electrostatic field felt at the redox centre, and the kinetics of electron transfer, through the dipole moment they generate.

Amino Acid Sequence↗

Dopamine receptor blockade increases dopamine D2 receptor and glutamic acid decarboxylase mRNAs in mouse substantia nigra.

To study the influence of dopaminergic activity on the expression of dopamine D2 receptors and glutamic acid decarboxylase in substantia nigra, mice were treated daily for several days with an irreversibly acting dopamine D1 and dopamine D2 receptor antagonist N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) or with a selective irreversible D2 dopamine receptor antagonist fluphenazine-N-mustard. Mice were killed 24 h after the last injection. Dopamine D1 and dopamine D2 receptors were determined by receptor autoradiography, and dopamine D1 and dopamine D2 receptor mRNA and glutamic acid decarboxylase mRNA were determined by in situ hybridization histochemistry. The results showed that treatment with EEDQ, which blocked 80% to 85% of the dopamine D2 and dopamine D1 receptors in substantia nigra, increased the levels of dopamine D2 receptor mRNA in substantia nigra by about 27%. Treatment with fluphenazine-N-mustard, which blocked about 85% of the dopamine D2 receptors in substantia nigra but had no significant effect on dopamine D1 receptors, increased the levels of dopamine D2 receptor mRNA by about 34%. There were no detectable levels of dopamine D1 receptors, increased the levels of dopamine D2 receptor mRNA by about 34%. There were no detectable levels of dopamine D1 receptor mRNA in substantia nigra either in control animals or in animals treated with the dopamine receptor antagonists. Glutamic acid decarboxylase mRNA was expressed in several regions of the mid-brain but only that expressed in substantia nigra was altered by treatment with dopamine receptor antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

Gamma-aminobutyric acid pathways in the cerebellum studied by retrograde and anterograde transport of glutamic acid decarboxylase antibody after in vivo injections.

Injections of characterized antibody against glutamic acid decarboxylase (GAD), the enzyme responsible for the synthesis of gamma-aminobutyric acid (GABA), were made into the cerebellum. Small cortical injections of anti-GAD antibody produced labeled stellate, basket, Purkinje, and Golgi cells and their processes at the injection site. Anterograde transport of GAD antigen-antibody complexes in Purkinje cell axons caused intense labelling of terminals in deep cerebellar and several vestibular nuclei. Small groups of mossy fiber rosettes labeled and produced retrograde labeling and GAD immunoreactivity in a small number of pleomorphic neurons in the deep cerebellar nuclei. Injections into the dentate nucleus produced retrograde labeling in Purkinje cell bodies and anterograde label in a small number of mossy fiber rosettes. All projections conformed to previously reported topographic distributions of corticonuclear and nucleocortical cerebellar pathways. These findings confirm the GABA content of most Purkinje cell-deep nuclei connections and provide new evidence for a GABA component in part of the nucleocortical pathway in the cerebellum. Immunocytochemical controls for specificity were conducted by injections of preimmune rabbit serum as a substitute for GAD antibody. Only nonspecific labeling was obtained in these cases. Colchicine caused a cumulative enhancement of GAD immunoreactivity in all cases. The present studies indicate that the method of in vivo antibody injections can be utilized to study chemically specific connections in nervous tissue.

Animals↗

Effect of cholinomimetics on the release and uptake of L-[3H] glutamic acid in rat neostriatum.

The effects of cholinomimetics on the release and uptake of L-glutamic acid have been studied by means of local superfusion of rat neostriatum (in vivo) and using striatum slices (in vitro). Cholinomimetics regulate the release of L-glutamic acid through both muscarinic (m-) and nicotinic (n-) choline receptors according to the mechanism of negative feedback. Cholinomimetics regulate release through presynaptic receptors. The effect of n-cholinomimetics is mediated by neostriatum interneurons.

Animals↗