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

Two direct HPLC analytical methods for the screening of the major indole alkaloids of Catharanthus roseus hairy roots and their iridoid precursors have been developed. Photodiode array and fluorescence detection were performed. The separation was achieved on a reversed-phase C18 column. The first method allowed the separation of catharanthine, serpentine, tabersonine, vindoline, vinblastine, and vincristine in 20 min. Ajmalicine, tryptophan, tryptamine and secologanine were separated using the second method in 13 min. The identification of the compounds was based on the retention time and the comparison of UV spectra with those of authentic standards. A simplified alkaloid extraction method was developed in order to accelerate sample preparation. The assays were successfully used to quantify major compounds of the secondary metabolism of hairy root cultures of C. roseus, thus providing a reliable tool for rapid screening of C. roseus secondary metabolite samples. In these cultures, ajmalicine, serpentine, catharanthine, tabersonine, and tryptamine were detected, but tryptophan, vindoline, vinblastine and vincristine were not.
 ...
PMID:Screening of Catharanthus roseus secondary metabolites by high-performance liquid chromatography. 1206 66

We used solid-state deuterium NMR spectroscopy and an approach involving geometric analysis of labeled alanines (GALA method) to examine the structure and orientation of a designed synthetic hydrophobic, membrane-spanning alpha-helical peptide in phosphatidylcholine (PC) bilayers. The 19-amino-acid peptide consists of an alternating leucine and alanine core, flanked by tryptophans that serve as interfacial anchors: acetyl-GWW(LA)(6)LWWA-ethanolamine (WALP19). A single deuterium-labeled alanine was introduced at different positions within the peptide. Peptides were incorporated in oriented bilayers of dilauroyl- (di-C12:0-), dimyristoyl- (di-C14:0-), or dioleoyl- (di-C18:1(c)-) phosphatidylcholine. The NMR data fit well to a WALP19 orientation characterized by a distinctly nonzero tilt, approximately 4 degrees from the membrane normal, and rapid reorientation about the membrane normal in all three lipids. Although the orientation of WALP19 varies slightly in the different lipids, hydrophobic mismatch does not seem to be the dominant factor causing the tilt. We suggest rather that the peptide itself has an inherently preferred tilted orientation, possibly related to peptide surface characteristics or the disposition of tryptophan indole anchors relative to the lipids, the peptide backbone, and the membrane/water interface. Additionally, the data allow us to define more precisely the local alanine geometry in this membrane-spanning alpha-helix.
 ...
PMID:Geometry and intrinsic tilt of a tryptophan-anchored transmembrane alpha-helix determined by (2)H NMR. 1220 73

A sensitive, rapid and specific method for the determination of tryptophan(Trp) in serum by high performance liquid chromatography with fluorescence detection (HPLC-FLD) has been established. Serum sample was precipitated by 5% perchloric acid solution and centrifuged to remove protein and then assayed by HPLC-FLD. The operating conditions were Nova-Pak C18 column (3.9 mm i.d x 150 mm, 4 microns), 5 mmol/L KH2PO4 as the mobile phase at a flow rate of 1.0 mL/min. The fluorescence detector was operated at lambda ex 254 nm and lambda em 338 nm. The method was proved to be linear in the range of 0.49 mumol/L-490.00 mumol/L with a regression coefficient of 0.9999. The minimum detection limit was 0.10 mumol/L. The recoveries were 97.2%-98.6%. The intra-batch and inter-batch RSDs were 2.0% and 3.2% respectively. The detection time of serum Trp was within 5 min after injection. The results suggest that this method is simple, fast, accurate and convenient.
 ...
PMID:[Rapid analysis of tryptophan in serum by high performance liquid chromatography with fluorescence detection]. 1254 20

During gamma-irradiation (5 kGy) of aqueous tryptophan (Trp) solutions small amounts of 5-, 6-, and 7-hydroxytryptophan (OH-Trp) (0.04-0.08 Mol-%) are formed. Protein rich food like shrimps contain reasonable amounts of non-protein bound Trp (100 mg/kg). In order to detect the treatment of shrimps with gamma-irradiation a method for the determination of OH-Trp in gamma-irradiated shrimps was developed. After homogenization, squeezing of shrimp samples and protein precipitation, a two-step-SPE-clean up was performed using a C18-cartridge and a propylsulfonic acid cation-exchange SPE followed by HPLC analysis with electrochemical detection (750 mV). Results showed that 5-OH-Trp contents in shrimp samples increased with applied doses up to 3 kGy and then decreased with higher doses. Other OH-Trp isomers were not detectable in the irradiated shrimps. Similarly no formation of 4-, 6-, and 7-OH-Trp was detected in model solutions containing the same amino acid composition as in shrimps. This indicates a suppression of the reaction of OH-radicals with Trp by the 300 fold molar excess of other amino acids acting as well as radical scavengers. Therefore, non-physiological OH-Trp isomers formed from free Trp are not suitable as markers for the detection of gamma-irradiated protein-rich foodstuff.
 ...
PMID:Suitability of tryptophan radiation products as markers for the detection of gamma-irradiated protein rich food. 1520 90

A new, rapid, sensitive, and reproducible reversed-phase liquid chromatographic (LC) method with photodiode array detection is described. It allows, in a single run of 30 min, simultaneous separation of 6 pharmaceutically and biologically important Catharanthus roseus leaf and root terpenoid indole alkaloids (TIAs) and 3 of their precursors: TIA precursors tryptophan, tryptamine, and loganine; and TIAs serpentine, catharanthine, ajmalicine, vincristine, vinblastine, and vindoline. The method involves the use of a Phenomenex Luna 5 microm, C18 column (250 mm x 4.6 mm id) and a linear binary gradient mobile phase profile. Detection is performed at 220 and 254 nm, which provided good absorptivity for all of the roseus compounds listed above and gave a minimum detection limit of 0.02 microg/mL. The extraction efficiency, peak purity, and homogeneity parameters of the profiles could be validated using a photodiode array detector. The method was successfully used to quantify major components of leaf and root extracts of C. roseus accessions. The new method thus provides a reliable tool for rapid screening of C. roseus samples in large numbers, which is needed in breeding/genetic engineering and genetic mapping experiments and for monitoring the reaction products, in the in vitro/in vivo conversions of precursors into products, and vice versa.
 ...
PMID:Simultaneous quantification of some pharmaceutical Catharanthus roseus leaf and root terpenoid indole alkaloids and their precursors in single runs by reversed-phase liquid chromatography. 1567 38

A procedure based on liquid chromatography-mass spectrometry (LC-MS) is described for determination of caffeine, theobromine, theophylline, taurine in different dietary supplements. After addition of tryptophan as internal standard, both solid and liquid specimens were extracted with 4 ml of hexane/isopropanol (9:1). Chromatography was performed on a C18 reversed-phase column using water/methanol/acetic acid (75:20:5, v/v/v) as a mobile phase. Analytes were determined in LC-MS single ion monitoring mode with atmospheric pressure ionization-electrospray (ESI) interface. The method was validated in the range 0.1-500 and 0.06-500 microg/ml or microg/g for taurine and caffeine, respectively; 0.06-100 microg/ml or microg/g for theobromine and theophylline. Mean recoveries ranged between 70.1 and 94.4% for different analytes. The quantification limits were 0.1 microg/ml or microg/g for taurine and 0.06 microg/ml or microg/g for methylxanthines either in liquid samples or in solid samples. The method was applied to the analysis of various dietary supplements containing methylxanthines and taurine. Energetic drinks contained amounts of taurine in the range of hundreds to thousands microg/ml and ten times lower amounts of caffeine. Conversely, herbal powders, tablets and capsules mainly contained mg amounts of caffeine per gram of product with the other two methylxanthines in the range of ten to hundred microg/g.
 ...
PMID:Development and validation of a high-performance liquid chromatography-mass spectrometry assay for methylxanthines and taurine in dietary supplements. 1574 Sep 10

Domoic acid (DA) is a naturally-occurring amino acid that causes a form of human intoxication called amnesic shellfish poisoning (ASP) following the consumption of shellfish. A rapid and sensitive HPLC-UV method has been developed for analysis of DA and analogues in shellfish without the need for SPE clean-up. Isocratic chromatographic separation of DA and its isomers from shellfish matrix interferences and from the prevalent amino acid, tryptophan, was achieved by careful control of the mobile phase pH. The optimised pH was found to be 2.5 when using a Luna(2) C18 column. Sample extraction was verified with control extracts from shellfish spiked at 5.0 and 10.0 microg/g of DA and with certified reference material. The average extraction efficiency was 98.5%. The calibration, based on mussel tissue spiked with DA standard, was linear in the range 0.05-5.0 microg/ml (r = 0.9999) and the detection limit (signal:noise 3:1) was better than 25 ng/ml. The DA assay achieved good precision; %RSD = 1.63 (intra-day, n = 6) and %RSD = 3.7 (inter-day, n = 8). This method was successfully applied to a variety of shellfish species, allowing the rapid screening of a large number of samples per day (20-30), without the need for SPE clean-up. Quantitative data were obtained for shellfish samples containing domoic acid in the concentration range 0.25-330 microg/g. Using the same chromatographic conditions, LC-MS3 was used to determine DA and its isomers, isodomoic acid D and epi-domoic acid, in scallop tissues.
 ...
PMID:Improved high-performance liquid chromatographic method for the determination of domoic acid and analogues in shellfish: effect of pH. 1577 Apr 70

The aim of this study was to characterize a novel human autoantibody-autoantigen system represented as cytoplasmic discrete speckles (CDS) in indirect immunofluorescence (IIF). A distinct CDS IIF pattern represented by 3-20 discrete speckles dispersed throughout the cytoplasm was identified among other cytoplasmic speckled IIF patterns. The cytoplasmic domains labelled by human anti-CDS-1 antibodies did not co-localize with endosome/lysosome markers EEA1 and LAMP-2, but showed partial co-localization with glycine-tryptophan bodies (GWB). CDS-1 sera did not react with several cellular extracts in immunoblotting and did not immunoprecipitate recombinant GW182 or EEA1 proteins. The typical CDS-1 IIF labelling pattern was abolished after delipidation of HEp-2 cells. Moreover, CDS-1 sera reacted strongly with a lipid component co-migrating with phosphatidylethanolamine (PE) in high performance thin-layer chromatography (HPTLC)-immunostaining of HEp-2 cell total lipid extracts. The CDS-1 major molecular targets were established by electrospray ionization-mass spectrometry (ESI-MS), HPTLC-immunostaining and chemiluminescent enzyme-linked immunosorbent assay as diacyl-PE species, containing preferentially a cis-C18 : 1 fatty acid chain at C-2 of the glycerol moiety, namely 1,2-cis-C18 : 1-PE and 1-C16 : 0-2-cis-C18 : 1-PE. The clinical association of CDS-1 sera included a variety of systemic and organ-specific autoimmune diseases but they were also observed in patients with no evidence of autoimmune disease.
 ...
PMID:Human autoantibodies to diacyl-phosphatidylethanolamine recognize a specific set of discrete cytoplasmic domains. 1648 57

Single-component adsorption isotherm data of l-tryptophan on a C18-bonded silica column were acquired by frontal analysis (FA), with aqueous mobile phases containing 2.5, 5, and 7.5% of acetonitrile (ACN) or 7, 10, 15, and 20% of methanol (MeOH). Most of these isotherms have two inflection points and three different parts. The low and the high concentration parts exhibit langmuirian behavior. The intermediate part exhibits anti-langmuirian behavior. The inflection points shift toward higher concentrations with increasing mobile phase concentration in ACN or MeOH, which causes the differences in the isotherm profiles. The nature of the organic modifier and its concentration affect only the isotherm profile and the numerical values of its parameters, not the nature of the best model, which is the bi-Moreau model in all cases. The isotherm profiles depend on the experimental conditions because they affect the intensity of the adsorbate-adsorbate interactions. Overloaded band profiles of tryptophan were recorded with the seven mobile phase compositions. They were used to determine the best values of the isotherm coefficients by the inverse method (IM) of chromatography. There is an excellent agreement between the values of these parameters obtained by FA and by IM. Increasing the concentration of either ACN or MeOH in the mobile phase causes a slight decrease in the saturation capacities of the low and the high energy sites, and in the adsorption constant of the low energy sites. The adsorption constant of the high energy sites increases with increasing concentration of either solvent or is little affected. The adsorbate-adsorbate interaction constants of both low and high energy sites increase for both solvents. Saturation capacities of the high energy sites are higher for ACN than for MeOH.
 ...
PMID:Effect of the mobile phase composition on the adsorption behavior of tryptophan in reversed-phase liquid chromatography. 1653 Feb 6

Commercially important edible nut seeds were analyzed for chemical composition and moisture sorption. Moisture (1.47-9.51%), protein (7.50-21.56%), lipid (42.88-66.71%), ash (1.16-3.28%), total soluble sugars (0.55-3.96%), tannins (0.01-0.88%), and phytate (0.15-0.35%) contents varied considerably. Regardless of the seed type, lipids were mainly composed of mono- and polyunsaturated fatty acids (>75% of the total lipids). Fatty acid composition analysis indicated that oleic acid (C18:1) was the main constituent of monounsaturated lipids in all seed samples. With the exception of macadamia, linoleic acid (C18:2) was the major polyunsaturated fatty acid. In the case of walnuts, in addition to linoleic acid (59.79%) linolenic acid (C18:3) also significantly contributed toward the total polyunsaturated lipids. Amino acid composition analyses indicated lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) to be the first limiting amino acid as compared to human (2-5 year old) amino acid requirements. The amino acid composition of the seeds was characterized by the dominance of hydrophobic (range = 37.16-44.54%) and acidic (27.95-33.17%) amino acids followed by basic (16.16-21.17%) and hydrophilic (8.48-11.74%) amino acids. Trypsin inhibitory activity, hemagglutinating activity, and proteolytic activity were not detected in the nut seed samples analyzed. Sorption isotherms (Aw range = 0.08-0.97) indicated a narrow range for monolayer water content (11-29 mg/g of dry matter). No visible mold growth was evident on any of the samples stored at Aw < 0.53 and 25 degrees C for 6 months.
 ...
PMID:Chemical composition of selected edible nut seeds. 1678 18


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>