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Results for “ASPARTIC ACID”

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At least 55 records · Page 3Linked to original sources
PubMed1977

A peptide containing aspartic acid, glutamic acid and serine in calf brain synaptic vesicles.

Free amino acids and other amino compounds in calf brain synaptic vesicles were identified and determined by thin-layer chromatography and ion-exchange chromatography. The vesicles contained ten identified amino acids with glutamic acid, aspartic acid, taurine and gamma-aminobutyric acid in the highest concentrations, and also cysteic acid (or cysteinesulfinic acid), glutamine, alanine, serine, glycine and lysine. The vesicles also contained certain unknown acid-labile, ninhydrin-positive compounds, one of which was a peptide yielding, after acid hydrolysis, about 40% aspartic acid, 30% serine, 15% glutamic acid, 10% glycine and possibly some alanine and lysine. The concentration of the peptide in the vesicles was as high as that of all the other amino compounds together.

Amino Acids↗
PubMed1991

Stimulation of 22Na+ efflux from rat forebrain membrane vesicles by L-glutamic acid, L-aspartic acid and kainic acid.

A glass fiber filter assay method is described for measuring 22Na+ efflux stimulated by L-glutamic acid, L-aspartic acid and kainic acid from osmotically sensitive membrane vesicles prepared from rat brain. L-Glutamic acid and L-aspartic acid showed the greatest efficacy for the stimulation of 22Na+ efflux with EC50 values of 3 microM. Kainic acid produced 28% of the maximal efflux seen with L-glutamic acid or L-aspartic acid with an EC50 value of 1.5 microM. Quisqualic acid never showed statistically significant increases in 22Na+ efflux over control experiments. N-Methyl-D-aspartic acid showed no detectable efflux activity in this preparation. DL-2-Amino-4-phosphonobutyric acid (APB) inhibited up to 40% of the 50 microM L-glutamic acid-stimulated or 50 microM L-aspartic acid-stimulated 22Na+ efflux with an IC50 value of 1.5 nM. Calcium was required for the inhibitory action of APB, but not for the stimulatory actions of L-glutamic, L-aspartic, or kainic acids. L-Glutamic, L-aspartic, and kainic acids at concentrations above 100 microM were found to inhibit rather than to stimulate 22Na+ efflux. Veratridine (1 microM) had no influence on the 22Na+ efflux component which was produced by L-glutamic or kainic acids. We are unable to firmly establish the mechanism for the stimulated 22Na+ efflux.

Animals↗
PubMed1999

Blood-brain barrier produces significant efflux of L-aspartic acid but not D-aspartic acid: in vivo evidence using the brain efflux index method.

The brain efflux index method has been used to clarify the mechanism of efflux transport of acidic amino acids such as L-aspartic acid (L-Asp), L-glutamic acid (L-Glu), and D-aspartic acid (D-Asp) across the blood-brain barrier (BBB). About 85% of L-[3H]Asp and 40% of L-[3H]Glu was eliminated from the ipsilateral cerebrum within, respectively, 10 and 20 min of microinjection into the brain. The efflux rate constant of L-[3H]Asp and L-[3H]Glu was 0.207 and 0.0346 min(-1), respectively. However, D-[3H]Asp was not eliminated from brain over a 20-min period. The efflux of L-[3H]Asp and L-[3H]Glu was inhibited in the presence of excess unlabeled L-Asp and L-Glu, whereas D-Asp did not inhibit either form of efflux transport. Aspartic acid efflux across the BBB appears to be stereospecific. Using a combination of TLC and the bioimaging analysis, attempts were made to detect the metabolites of L-[3H]Asp and L-[3H]Glu in the ipsilateral cerebrum and jugular vein plasma following a microinjection into parietal cortex, area 2. Significant amounts of intact L-[3H]Asp and L-[3H]Glu were found in all samples examined, including jugular vein plasma, providing direct evidence that at least a part of the L-Asp and L-Glu in the brain interstitial fluid is transported across the BBB in the intact form. To compare the transport of acidic amino acids using brain parenchymal cells, brain slice uptake studies were performed. Although the slice-to-medium ratio of D-[3H]Asp was the highest, followed by L-[3H]Glu and L-[3H]Asp, the initial uptake rate did not differ for both L-[3H]Asp and D-[3H]Asp, suggesting that the uptake of aspartic acid in brain parenchymal cells is not stereospecific. These results provide evidence that the BBB may act as an efflux pump for L-Asp and L-Glu to reduce the brain interstitial fluid concentration and act as a static wall for D-Asp.

Algorithms↗
PubMed1997

Free lysine, glycine, alanine, glutamic acid and aspartic acid reduce the glycation of human lens proteins by galactose.

The amino acids lysine, glycine, alanine, glutamate and aspartate formed adducts with galactose at physiological pH and temperature as shown by incorporation of U[14C] galactose. The percentage of galactose reacting with lysine, glycine, alanine, glutamate and aspartate was 4.5 to 7.8, 7.9 to 10.8, 3.2 to 4.6, 2.8 to 4.8 and 3 to 5.2, respectively. Studies with lysine showed that the extent of glycation of the free amino acid increased with time. Incubation of lens homogenate with galactose, effected glycation of proteins. Addition of lysine in concentrations of 5 and 10 mM to equimolar concentrations of galactose decreased the glycation of lens proteins by 64% to 71%; glycine, alanine, glutamate and aspartate decreased glycation by 23 to 68%, 32 to 61%, 35 to 56% and 26 to 61% respectively. Under similar conditions, glycine reacts to a greater extent than lysine, alanine, glutamic and aspartic acids. However, lysine was more effective than glycine, alanine, aspartic and glutamic acids in decreasing glycation of lens proteins by galactose. The decrease of glycation with added lysine increased with time. In general increase of amino acid concentration rather than that of sugar augmented the decrease of glycation of lens proteins.

Adult↗
PubMed2003

Feasibility study: fast liquid chromatography-mass spectrometry for the quantification of aspartic acid in an aspartate drug.

We have studied the feasibility of fast high-performance liquid chromatography coupled to electrospray ionization mass spectrometry in the selected ion monitoring mode for the quantitative determination of aspartic acid in an aspartate drug. Internal standardization was required, but mass spectrometric detection allowed for very short retention times of approximately 0.5 min for the analyte and the internal standard without chromatographic separation. The analytical system was found stable, as demonstrated by multiple injections giving a coefficient of variation of 4% for the peak area ratio of aspartic acid and glutamic acid. Calibrations were linear between 0.5 ng and 150 ng aspartic acid injected, with accuracies between 99.8% and 102% found for the back-calculated amounts. Investigation of several drug batches gave reasonable results. Therefore, the method appeared feasible for the determination of aspartic acid in an aspartate drug from 0.3 wt% to 100 wt% aspartic acid.

Journal Article↗
PubMed1977

Biodegradability and tissue reaction of random copolymers of L-leucine, L-aspartic acid, and L-aspartic acid esters.

A series of copoly(alpha-amino acids) with varying percentages of hydrophilic (L-aspartic acid) and hydrophobic monomers (L-leucine, beta-methyl-L-aspartate, and beta-benzyl-L-aspartate) were implanted subcutaneously in rats and the macroscopic degradation behavior was studied. Three groups of materials (A,B,C) with different ranges of hydrophilicity were distinguished: A) hydrophobic materials showed no degradation after 12 weeks; B) more hydrophilic materials revealed a gradual reduction in size of the samples, but were still present after 12 weeks; and C) hydrophilic copolymers disappeared within 24 hr. The tissue reactions caused by the materials of group A resembled that of silicone rubber, whereas those of group B showed a more cellular reaction.

Animals↗