Glutamate radioactive

FIGURE 10.10 Structural formula of folic acid and related compounds. 1 — [3, 5, 7,9- H]folic acid (boldfaced letter H denotes radioactivity), 2 — pterine-6-carboxylic acid, 3 — /)-aminobenzoyl-L-glutamic acid. 

Berl, S., Nicklas, W. J. and Clarke, D. D. Compartmentation of citric acid cycle metabolism in brain labelling of glutamate, glutamine, aspartate and gaba by several radioactive tracer metabolites. J. Neurochem. 17 1009-1015, 1970. 

N as a tracer, ammonia 106 exchange reaction 105 glutamic add 106 GOGAT system 106 radioactive tracer 106 N2 and HD formation 109 N2 fixation in non-leguminous plants, actinomycetes 110 actinorhizal systems 110 NAD 74 nanocrystal 263 nanocrystalline materials 171... 

Nucleotides - [AMINO AC IDS - L-MONOSODIUM GLUTAMATE (MSG)] (Vol 2) -as antibiotics [ANTIBIOTICS - NUCLEOSIDES AND NUCLEOTIDES] (Vol 3) -catabolism of [MINERALNUTRIENTS] (Vol 16) -electrodes for [BIOPOLYMERS - ANALYTICAL TECHNIQUES] (Vol 4) -phosphorus nmr [MAGNETIC SPIN RESONANCE] (Vol 15) -as radioactive tracers [RADIOACTIVETRACERS] (Vol 20)... 

Thermal polylysine also catalyzes the formation of a-ketoglutaric acid from glutamic acid with CuCl25). A reaction mixture of lysine-rich proteinoid (20 mg), 14C(U)-l-glutamate (0.1 mM), and CuCl (0.1 mM) in 6 ml of Britton-Robinson buffer (pH 7.0) is incubated at 37.5 °C for 2 hours. More than 40 % of the radioactivity used is recorded in a-ketoglutaric add by paperchromatography of the reaction mixture25 . Free lysine and Leuehs poly-L-lysine have no activity 2S). The reaction obeys Michaelis-Menten kinetics at optimum pH 7.0 25). 

Synaptic neurotransmission in brain occurs mostly by exocytic release of vesicles filled with chemical substances (neurotransmitters) at presynaptic terminals. Thus, neurotransmitter release can be detected and studied by measuring efflux of neurotransmitters from synapses by biochemical methods. Various methods have been successfully employed to achieve that, including direct measurements of glutamate release by high-performance liquid chromatography of fluorescent derivatives or by enzyme-based continuous fluorescence assay, measurements of radioactive efflux from nerve terminals preloaded with radioactive neurotransmitters, or detection of neuropeptides by RIA or ELISA. Biochemical detection, however, lacks the sensitivity and temporal resolution afforded by electrophysiological and electrochemical approaches. As a result, it is not possible to measure individual synaptic events and apply quantal analysis to verify the vesicular nature of neurotransmitter release. 

The use of sulfur mustard as a vesicant CW agent implies that proteins of the skin are a primary target. It was found that upon exposure of human callus to [14C]sulfur mustard, a significant part of the radioactivity was covalently bound to keratin (30). Most of the radioactivity (80%) bound to keratin could be removed by treatment with alkali, indicating the presence of adducts to glutamic and/or aspartic acid residues. 

The experiments discussed were performed with Lactobacillus arabinosus using glutamic acid, alanine, and proline as the test amino acids. The detailed experimental procedures have been described (21, 23, 27). Washed resting cells are incubated in a phosphate buffer with the radioactive amino acid, centrifuged, and extracted to release the amino acid, which is then measured enzymically or by isotopic methods. 

The difference in radioactivity between the protein and dialyzing compartments was used as a measure of bound acetyl glutamate (30) in one case, for example, it was determined that 100 counts had bound, with a standard deviation of 20. It appears that a statistically significant number of experiments is required to ascertain the binding of acetyl glutamate, in view of the small magnitudes and large experimental errors involved. 

The fractions may be analyzed spectrophotometrically using the ninhydrin reaction or spectrofluorometrically using fluorescamine (Chapter 6). If radioactive glutamate or aspartate is used, the radioactivity in an appropriate aliquot should be determined with a scintillation counter (Chapter 3). 

The histidine catabolic pathway is discussed under Folate in Chapter 9. The material reveals that histidine is catabolized to produce glutamate. Glutamate in turn, can be converted to a-ketoglutarate and completely oxidized to CO in the Krebs cycle. In the study depicted in Figure 8,26, the dietary histidine was spiked with I Cjhistidine, The term "spiked" means that only a very small proportion of the histidine contained carbon-14. The metabolic behavior of the radioactive histidine, which can be followed, mirrors the metabolic fate of nonradioactive histidine in the diet. All of the CQz exhaled by the rats can be easily collected, The " COj present in the rat s breath can be measured by use of a liquid scintillation counter. The amount of CO2 produced directly mirrors the proportion of histidine, absorbed from the diet that was degraded the rat s body. 

The biosynthesis of 5-aminolevulinic acid (ALA, a chlorophyll precursor) was studied in greening barley leaves. Preliminary long-term experiments showed that radioactivity from glycine-2-C (or-carbon labeled) and from glutamate-2,S.-C " (methylene carbons labeled) appeared in ALA. The specific activity data of a more detailed study is shown in Figure 6-6. What conclusions can be drawn ... 

A correlation of configuration of (-t- )-a-methyltropidine (LXXXIV) therefore gave a clue to the absolute configuration of labeled hyoscyamine. This was achieved by converting it (82) into the V-dimethyl-glutaminol antimer XCa, via the tetraol LXXXVIII and with periodate. The reduction of A,A-dimethyl-L-(-f )-glutamic acid afforded its antimer XCb. Consequently, C-1 was radioactive in hyoscyamine, but, C-5 was not. This ultimate information concerning the biosynthesis of the tropane skeleton had not been anticipated. 

Schmitt A, Kugler P (1999) Cellular and regional expression of glutamate dehydrogenase in the rat nervous system non-radioactive in situ hybridization and comparative immunocytochemistry. Neuroscience 92 293-308. 

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