Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q3SYG4 (C18)
 23,707 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A rapid, isocratic method for the determination of tryptophan in Escherichia coli fermentation broths by reversed-phase HPLC is described. Tryptophan can be measured in fermentations containing either chemically defined media or media with hydrolyzed protein supplements. The procedure was rugged and rereproducible (RSD = 1.7%). The sample response was found to be linear up to 10 mcg of tryptophan/ml. Two different columns--Vydac C18 30 mm and "deactivated" SupelcoSil LC-18-DB--were compared and evaluated for use in the analysis. The deactivated columns had the residual silanols on the silica gel chemically inactivated to reduce the interaction with basic groups or analytes. The deactivated column was found to provide better peak shape (peak assymetry factor less than 1.1) and superior efficiency (plate count greater than 40000/m) and durability (greater than 3000 injections per column) than the non-deactivated column. The procedure described was found to be more selective than a fluorometric procedure.
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PMID:A method for the quantitation of tryptophan in Escherichia coli fermentation broth by isocratic high-performance liquid chromatography with ultraviolet detection. 180 56

A rapid and simple reversed-phase (using muBondapak C18 as the stationary phase) liquid chromatographic method with fluorimetric detection is described for the quantitation of 5-hydroxytryptamine in whole blood. The rapidity and simplicity of the method are explained by the absence of a pretreatment. 5-Fluoro-dl-tryptophan was used as internal standard. The mobile phase was 0.01 M phosphate buffer (pH 4.5) with 0.0025 M 1-heptanesulfonic acid and 20% methanol. The detection wavelength were 302 nm for excitation and 340 nm for emission. Analysis time was 10 min with retention times for 5-hydroxytryptamine of 9 min and for 5-fluoro-dl-tryptophan of 7 min. This method is proposed for biological exploration of psychiatric disorders involving 5-hydroxytryptamine and would be useful for tryptophan.
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PMID:Rapid determination of 5-hydroxytryptamine in whole blood by liquid chromatography with fluorimetric detection. 181 Sep 50

A series of materials with chemically bonded C18 phase for use as the packings in clean-up columns for solid-phase extraction were prepared. The effects of the monomeric and/or polymeric structure of the chemically bonded phase and of the porous structure of the silica gel support on the recovery of tryptophan and two of its metabolites used as test substances were considered. It appeared that the best recoveries of at least 60% of the three test substances were obtained on material of the "monomer" type containing chemically bonded C18 phase characterized by a high coverage density of alpha RP approximately 3.8 mumol/m2. The use of a silica gel support with a larger pore size and volume permits not only the effective isolation of individual substances, e.g., from urine, but also their 5-fold concentration.
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PMID:Effect of the structure and density of chemically bonded C18 phase on the recovery of tryptophan and its metabolites from human urine. 271 51

The purpose of the present study was to determine whether ultraviolet light (UV) irradiation of amino acids produces compounds with affinity for the Ah receptor. Aqueous solutions of L-tryptophan were exposed to radiation from an unfiltered high-pressure mercury lamp. The photoproducts formed were solvent-extracted or concentrated on Sep-Pak C18 cartridges. The concentrated extracts or eluants were treated for their ability to compete with 3H-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Binding was assayed in liver cytosolic preparations from Sprague-Dawley rats using a technique based on hydroxylapatite separation. Photoproducts with receptor affinity were formed in a time-dependent manner. Histidine and tryptamine also gave products upon UV irradiation that competed with TCDD. Commercial tryptophan, at least aged, contained trace amounts of impurities with receptor affinity. Analysis by TLC and high-pressure liquid chromatography of the photo-products of tryptophan showed a minimum of three different binding compounds. Two of the products were studied in greater detail. One of them, showing UV absorbance and yellow fluorescence, gave a molecular ion (M+) of 284 and the other gave M+ 312 but showed little UV absorption and fluorescence. The concentration, based on mass spectrometry quantifications, of the two compounds that displaced more than 50% of TCDD was found to be extremely low, giving Kd values of 0.44 nM (M+ 312) and 0.07 nM (M+ 284). The existence of high affinity receptors for oxidized amino acids is postulated and their possible role in the proliferative cellular responses to TCDD and tryptophan is discussed briefly.
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PMID:Certain photooxidized derivatives of tryptophan bind with very high affinity to the Ah receptor and are likely to be endogenous signal substances. 282 60

High-performance liquid chromatography, with serial electrochemical and ultraviolet detectors, was used with a reduced activity catecholamine C18 column to separate and quantify compounds important in the serotonergic and octopamine pathways in lobster hemolymph. The chromatographic mobile phase was composed of potassium dihydrogenphosphate buffer, trichloroacetic acid, sodium dodecyl sulfate, the sodium salt of ethylenedinitrilotetraacetic acid and the organic solvents, acetonitrile and methanol. The compounds serotonin, 5-hydroxyindoleacetic acid, tryptophan, 5-hydroxytryptophan, tryptamine, melatonin, octopamine and tyrosine were well resolved within 13 min. Good electrode maintenance, the use of a silica gel precolumn and careful sample preparation were necessary to give a stable baseline, high resolution of these compounds and reproducibility of retention times and peak heights. The electrochemical detector extended the range of detection to the picogram level. Because of the instability of the solutes and of the chromatographic baseline, sample preparation procedures were investigated. Deproteinization with ammonium sulfate gave the best recovery of the compounds of interest and the most stable baseline with the electrochemical detector. Peaks in the hemolymph were characterized by addition of standards, dual detection (electrochemical and ultraviolet) and the enzyme peak shift technique. With this methodology, important endogenous neurohormones in the hemolymph of lobsters can be quantitatively determined with respect to the molt cycle.
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PMID:Liquid chromatographic procedures for the analysis of compounds in the serotonergic and octopamine pathways of lobster hemolymph. 314 48

Tektins, protein components of stable protofilaments from sea urchin sperm flagellar outer doublet microtubules (Linck, R. W., and G. L. Langevin, 1982, J. Cell Sci., 58:1-22), are separable by preparative SDS PAGE into 47-, 51-, and 55-kD equimolar components. High resolution two-dimensional tryptic peptide mapping reveals 63-67% coincidence among peptides of the 51-kD tektin chain and its 47- and 55-kD counterparts, greater than 70% coincidence between the 47- and 55-kD tektins, but little obvious similarity to either alpha- or beta-tubulin. With reverse-phase HPLC on a C18 column, using 6 M guanidine-HCl solubilization and a 0.1% trifluoroacetic acid/CH3CN gradient system (Stephens, R. E., 1984, J. Cell Biol. 90:37a [Abstr.]), the relatively less hydrophobic 51-kD tektin elutes at greater than 45% CH3CN, immediately followed by the 55-kD chain. The 47-kD tektin is substantially more hydrophobic, eluting between the two tubulins. The amino acid compositions of the tektins are very similar to each other but totally distinct from tubulin chains, being characterized by a greater than 50% higher arginine plus lysine content (in good agreement with the number of tryptic peptides) and about half the content of glycine, histidine, proline, and tyrosine. The proline content correlates well with the fact that tektin filaments have twice as much alpha-helical content as tubulin. Total hydrophobic amino acid content correlates with HPLC elution times for the tektins but not tubulins. The average amino acid composition of the tektins indicates that they resemble intermediate filament proteins, as originally postulated from structural, solubility, and electrophoretic properties. Tektins have higher cysteine and tryptophan contents than desmin and vimentin, which characteristically have only one residue of each, more closely resembling certain keratins in these amino acids.
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PMID:Biochemical characterization of tektins from sperm flagellar doublet microtubules. 355 79

Sulphydryl groups of E. coli tryptophanase (L-tryptophan indole lyase, E.C. 4.1.99.1) were made to react with a fluorescent maleimide derivative, N-(4-anilino-1-naphthyl)maleimide(ANM). By carefully controlling the reaction conditions it was possible to limit the extent of sulphydryl group modification. The modified enzyme was digested with (L-1-tosylamide-2-phenylethyl chloromethyl ketone)-trypsin. The fluorescent peptides obtained were analysed by reversed-phase high-performance liquid chromatography on a C18 column with a dual-monitoring system consisting of a UV and a fluorescence monitor connected in tandem. This was followed by the determination of the amino acid composition of the fluorescent peptides. Comparison of these results with the known, complete primary structure of tryptophanase from the K-12 strain of E. coli allowed the assignment of position 298 to the cysteine residue, which is more selectively modified by ANM under the conditions chosen and is involved in the maintenance of the catalytic activity.
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PMID:Characterization of the reactivity of sulphydryl groups in tryptophanase by a dual-monitoring high-performance liquid chromatographic system with a site-directed fluorescent reagent. 355 54

Twenty-three o-phthalaldehyde-mercaptoethanol derivatives of primary amino acids in serum were separated with Waters C18 5-microns Radial-Pak Resolve columns, using aqueous phosphate-methanol mobile phase with acetate and tetrahydrofuran as modifiers. Resolution is critical in this system for glutamine/histidine, citrulline/glycine/threonine/3-methylhistidine, and tryptophan/methionine derivatives, and is affected by small changes in column properties or mobile phase. However, pre-run adjustments in gradient scheme and/or mobile phase composition can usually be used to obtain chromatograms in which all derivatives can be quantitated. For this purpose, and for general method development, we have written two very fast, interactive programs for the Zenith Z-100 Microsoft BASIC compiler: RTGRAPH, for retention, separation, and resolution plots; and LCSIM for simulations of multisegment binary gradient elution. These programs are shown here to be useful and accurate in most aspects required for developing strategies for this method.
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PMID:Separation strategies for o-phthalaldehyde-mercaptoethanol derivatives of amino acids for reversed-phase high-performance liquid chromatography. 366 69

A procedure for quantitation of tryptophan in feedstuffs is described. It is based on barytic hydrolysis of material at 125 degrees C for 16 h, acidification of hydrolysate to pH 3 with HCl, high-performance liquid chromatography on Nova Pak C18 (Waters Assoc.), and spectrophotometric determination of tryptophan at 280 nm. The recovery of tryptophan from lysozyme added to samples ranges from 98.7 to 100%.
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PMID:High-performance liquid chromatography and ultraviolet spectrophotometry for quantitation of tryptophan in barytic hydrolysates. 381 97

The reactions between protein-bound amino acids and oxidizing lipid were investigated in a whey protein-methyl linolenate (C18:3)-water model system. The extent of fat oxidation was followed by measuring oxygen uptake, hydroperoxide formation and hydrocarbon (ethane and pentane) formation. Significant losses occurred with lysine (up to 71%), tryptophan (up to 31%) and histidine (up to 57%). Methionine was extensively oxidized to its sulphoxide but less than 2% was further oxidized to the sulphone. No other amino acids were affected. Increasing storage temperature (20 degrees, 37 degrees, 55 degrees) resulted in an enhancement of fat oxidation reactions and amino acid degradation. Increasing water activity (0.28, 0.65, 0.90) increased losses of lysine and tryptophan but had no influence on the oxidation of methionine, the level of remaining hydroperoxides or O2 uptake. Hydrocarbons were decreased. Limitation of O2 uptake to 1 mol/mol lipid instead of excess O2 (O2 uptake about 2.5 mol/mol lipid in 4 weeks) significantly reduced the degradation of lysine and tryptophan but had less influence on the oxidation of methionine. The level of remaining hydroperoxides was increased but hydrocarbons were unaffected.
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PMID:Reactions of proteins with oxidizing lipids. 1. Analytical measurements of lipid oxidation and of amino acid losses in a whey protein-methyl linolenate model system. 393 47


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