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Results for “Cysteic Acid”

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At least 19 recordsLinked to original sources
PubMed1994

Measurement of excitatory sulfur amino acids, cysteine sulfinic acid, cysteic acid, homocysteine sulfinic acid, and homocysteic acid in serum by stable isotope dilution gas chromatography-mass spectrometry and selected ion monitoring.

Oxidized sulfur-containing amino acids are recognized as agonists of excitatory amino acid receptors in the mammalian nervous system. Homologues of glutamic acid (homocysteine sulfinic acid and homocysteic acid) and aspartic acid (cysteine sulfinic acid and cysteic acid) have been shown to be agonistic to N-methyl-D-aspartate receptors in animal brain and have been demonstrated in brain tissue. Considerable evidence exists for the role of homocysteic acid and cysteine sulfinic acid as endogenous ligands for excitatory amino acid receptors. We report, for the first time, the quantitation of these compounds in normal human serum, by a newly developed gas chromatography-mass spectrometry method that employs stable isotope-dilution selected ion monitoring using internal standards prepared in our laboratory. We also report new methods of synthesis of stable isotope-labeled internal standards used in measuring cysteine sulfinic acid, cysteic acid, homocysteine sulfinic acid, and homocysteic acid.

Aspartic Acid↗
PubMed1983

Simultaneous determination of cysteine sulfinic acid and cysteic acid in rat brain by high-performance liquid chromatography.

A sensitive and specific assay method for cysteine sulfinic acid (CSA) and cysteic acid (CA) using high-performance liquid chromatography has been developed. The method includes post-column derivatization of various amino acids with o-phthalaldehyde in the presence of 2-mercaptoethanol. The column packed with cation-exchange resin (ISC-07/S1504, Shimadzu Scientific Instruments, Inc., Kyoto, Japan) was used for obtaining general separation of amino acids except CSA and CA, while the separation of CSA and CA was achieved using a strong-base anion exchange (ISA-07/S2504, Shimadzu Scientific Instruments) column. The fluorescence peak area for CSA was linear between 20 pmol and 5 nmol, whereas that for CA was 10 pmol to 5 nmol. The regional distribution of CSA, CA, and other amino acids in the rat brain was studied using this new assay method.

Amino Acids↗
PubMedDate not supplied

In vitro effect of the cysteine metabolites homocysteic acid, homocysteine and cysteic acid upon human neuronal cell lines.

Cysteine (CYS) is a non-essential amino acid which elicits excitotoxic properties via the N-methyl-D-aspartate (NMDA) subtype of the glutamate receptor. CYS levels are known to be elevated in association with neurological disease such as Alzheimers Disease (AD) and Parkinsons Disease (PD). We have previously reported studies investigating the toxicity of CYS and its major metabolite cysteinesulfinic acid (CSA) to human neuronal cell lines in vitro and in continuation of this we now report the toxicity of other compounds (Homocysteic Acid, HCA; Homocysteine, HCYS; and Cysteic Acid, CA) in the CYS metabolic pathway. Three cell lines, all of human origin and derived from separate discrete areas of the brain were used in the neurotoxicity assays. Lactate dehydrogenase (LDH) release was assayed as a measure of cell death. The cell lines investigated showed varying degrees of toxic responses which were the reverse of those seen when they were exposed to CYS or CSA. The SK.N.SH (Neuroblastoma) cell line, which exhibits a high toxic response to CYS and CSA, gave a low toxic response to HCA and CA while the TE 671 (Medulloblastoma) cell line, which exhibits a low toxic response to CYS and CSA, showed a high toxic response to HCYS, HCA and CA. However, the U-87 MG (Glioblastoma) cell line, which has a median toxic response to CYS and CSA, also has median response to HCYS, HCA and CA. These results show that toxic responses are cell-type specific for CYS and its metabolites and this may be reflected in the patterns of neurodegeneration observed in such diseases as AD and PD. HCYS is selectively toxic to medulloblastoma cells; this may explain why high HCYS levels result in neural tube defects in prenatal humans, where the same cell-type is involved.

Cell Line↗
PubMed1984

Methotrexate analogues. 19. Replacement of the glutamate side chain in classical antifolates by L-homocysteic acid and L-cysteic acid: effect on enzyme inhibition and antitumor activity.

Methotrexate (MTX) and aminopterin (AMT) analogues containing L-homocysteic acid or L-cysteic acid in place of L-glutamic acid were synthesized and tested as inhibitors of dihydrofolate reductase from L1210 cells and folyl polyglutamate synthetase from mouse liver. The ID50 against dihydrofolate reductase was comparable for the MTX and AMT analogues (0.04-0.07 microM), whereas the ID50 against folyl polyglutamate synthetase was 3- to 4-fold lower for the AMT analogues (40-60 microM) than for the MTX analogues (100-200 microM). Thus, N10-substitution has a greater effect on binding to folyl polyglutamate synthetase than dihydrofolate reductase. The cytotoxicity of these compounds was assayed in vitro against L1210 cells, and the AMT analogues again proved more potent (ID50 = 0.03-0.05 microM) than the MTX analogues (ID50 = 0.1-0.4 microM). A similarly increased potency was observed for the AMT analogues against L1210 leukemia in vivo. Though differential cell uptake cannot be ruled out as the basis of increased potency, it is possible that part of the activity of the AMT analogues involves interference with the intracellular polyglutamation of reduced folate cofactors, i.e., that they are "self-potentiating antifolates". Of the four compounds reported, the most active was N-(4-amino-4- deoxypteroyl )-L-homocysteic acid, which produced a 138% increase in life span (ILS) in L1210 leukemic mice when given on a modified bid X 10 schedule at a dose of 2 mg/kg. A comparable ILS was obtained with AMT itself at 0.24 mg/kg. Thus, replacement of gamma-CO2H by gamma-SO3H in the side chain does not decrease therapeutic effect. However, a higher dose is required, presumably to offset pharmacological differences reflecting the inability of the sulfonate group to be polyglutamated .

Amino Acids, Sulfur↗
PubMed1989

Hydrogen sulfide in combination with taurine or cysteic acid reversibly abolishes sodium currents in neuroblastoma cells.

Patch clamp studies of neuroblastoma cells have shown that in the presence of sodium hydrogen sulfide (NaHS; the in vitro precursor of H2S), addition of the sulfonated amino acids, taurine or cysteic acid resulted in reversible abolition of the inward sodium currents. This effect could also be demonstrated by preincubating cells for 3-20 min with 5-10 mM NaHS followed by replacement of the solution with taurine or cysteic acid in sulfide-free saline. Neither NaHS, taurine nor cysteic acid alone had any effect. The sulfhydryl reagents, beta-mercaptoethanol and dithiothreitol, were also found to abolish reversibly the sodium currents. As the effects of the above treatments were nearly identical, the synergistic action of NaHS with taurine or cysteic acid may result from reduction of the disulfide bonds between subunits comprising the sodium channel. The responses to NaHS and taurine, a putative neurotransmitter/neuromodulator, suggest that reductions in sodium channel function may be the mechanism(s) responsible for loss of central respiratory drive during H2S poisoning.

Amino Acids, Sulfur↗
PubMed1982

Cysteine sulfinic acid in the central nervous system: specific binding of [35S]cysteic acid to cortical synaptic membranes--an investigation of possible binding sites for cysteine sulfinic acid.

Specific binding sites for cysteine sulfinic acid, an excitatory amino acid, in crude synaptic membrane fractions of rat cerebral cortex were examined, using L-[35S]cysteic acid as a ligand. Two specific binding systems of [35S]cysteic acid were found, one Na+-dependent and the other Na+-independent. The Na+-independent specific binding of [35S]cysteic acid was saturable, with a Kd of 474 nM and Bmax of 3.29 pmol/mg protein. The binding was optimal at pH 7.4 and at 37 degrees C. Treatment of the membranes with proteases, concanavalin A, or Triton X-100 markedly reduced the binding. Of various compounds related to cysteic acid, L-cysteine sulfinic acid was the most effective competitor of this binding. These results indicate the existence of an Na+-independent specific binding site for cysteic acid in the synaptic membrane of rat cerebral cortex, which may be different from that for glutamate. Possible involvement of cysteine sulfinic acid as an endogenous ligand for this binding site is discussed.

Amino Acids, Sulfur↗
PubMed1985

Reversed-phase high-performance liquid chromatographic separation and quantitation of phenylthiohydantoin derivatives of 25 amino acids, including those of cysteic acid, 4-hydroxyproline, methionine sulfone, S-carboxymethylcysteine and S-methylcysteine.

A high-performance liquid chromatography system is presented which allows separation and quantitation (in the range 4-1000 pmol) of all common phenylthiohydantoin amino acids, including derivatives of 4-hydroxyproline, methionine sulfone and three differently modified forms of cysteine. By showing the actual solvent gradient during elution (as opposed to the programmed gradient) and by supplying information on the effects of minor changes in solvent-pH, column temperature, flow-rate, and concentration of 2-propanol in the gradient, we make guidelines available for fine-tuning the separation with new Ultrasphere-ODS (C18) columns.

Amino Acids↗
PubMed1994

Dietary cysteic acid serves as a precursor of taurine for cats.

The ability of cats to use dietary cysteic acid as a precursor for taurine was examined. For 39 wk, six groups of four specific-pathogen-free cats each were fed purified diets that provided either 1.25 g taurine or 0, 1.0, 2.0, 10 or 20 g cysteic acid/kg diet. Concentrations of taurine in plasma and whole blood were measured weekly for 13 wk and monthly until 39 wk. Muscle concentrations of taurine at 12 wk were measured on a biopsy sample of the semitendinosus muscle. Fecal and urinary excretions of taurine and cysteic acid at 17 wk were measured. Concentrations of taurine in plasma and whole blood were linearly and positively correlated with cysteic acid in the diet (r2 = 0.88). Urinary taurine, a major route of excess taurine excretion, was positively correlated with the cysteic acid concentration of the diet (r2 = 0.94). Muscle and whole-blood taurine concentrations were also positively correlated (r2 = 0.96) with dietary cysteic acid concentration. Gross and histopathological examinations were performed on cats fed diets containing 20 g cysteic acid/kg diet. No adverse gross clinical signs were observed in cats fed any diets containing cysteic acid; minor histopathologic changes of the pancreas and thyroid were found in three of four cats fed 20 g cysteic acid/kg diet. Results suggest that cats are able to use dietary cysteic acid as a precursor for taurine biosynthesis.

Administration, Oral↗
PubMed1992

The effect of dietary supplementation with cysteic acid on the plasma taurine concentration of cats maintained on a taurine-restricted diet.

The biochemical impairment in the taurine anabolic pathway of the cat has not yet been fully elucidated; however, a number of key enzymes are known to have reduced activity in the cat compared to the rat. There are a series of possible routes resulting in the formation of taurine, one of which is the decarboxylation of cysteic acid. The aim of this study was to investigate the effect of cysteic acid, as a precursor, on the circulating concentration of taurine. A group of twelve adult cats was fed a basal, canned diet containing 0.22 g taurine/kg fresh weight for a period of eighty-four days. The diet was supplemented with 2.0 g/kg fresh weight L-cysteic acid on day fifteen through fifty six and plasma taurine concentration was measured every two weeks throughout the study. The results showed that when the dietary intake of taurine was inadequate to maintain the plasma concentration above 40 mumol/L, the addition of L-cysteic acid to the diet gave rise to an increase in plasma taurine concentration in some cats. Eight of the twelve cats showed a significant rise in plasma taurine after dietary supplementation for six weeks (52.0 +/- 22.3 vs 212.4 +/- 97.9 mumol/L, p less than 0.01) and a subsequent decrease in plasma levels when the cysteic acid was withdrawn (65.6 +/- 37.1 mumol/L). The other four cats showed no significant rise in plasma taurine after six weeks supplementation (13.5 +/- 4.2 vs 35.5 +/- 19.4 mumol/L, ns). However, withdrawal of the cysteic acid resulted in a subsequent decrease in circulating levels of taurine (11.8 +/- 1.5 mumol/L, ns). These data indicate that the addition of cysteic acid to a taurine-restricted, canned diet will, in some cats, result in the biosynthesis of taurine. The plasma taurine concentration of the remaining cats, although not apparently increasing significantly, was maintained at a slightly higher constant level until the cysteic acid was withdrawn. These results suggest that cats are able to synthesise taurine via an alternative pathway utilising L-cysteic acid as a precursor, although the efficiency of this process differs considerably among individual animals.

Animal Nutritional Physiological Phenomena↗