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Chromatographic Behaviour (chromatographic + behaviour)
Selected AbstractsIdentification, purification and characterization of an acetoacetyl-CoA thiolase from rat liver peroxisomesFEBS JOURNAL, Issue 10 2000Vasily D. Antonenkov Acetoacetyl-CoA specific thiolases catalyse the cleavage of acetoacetyl-CoA into two molecules of acetyl-CoA and the synthesis (reverse reaction) of acetoacetyl-CoA. The formation of acetoacetyl-CoA is the first step in cholesterol and ketone body synthesis. In this report we describe the identification of a novel acetoacetyl-CoA thiolase and its purification from isolated rat liver peroxisomes by column chromatography. The enzyme, which is a homotetramer with a subunit molecular mass of 42 kDa, could be distinguished from the cytosolic and mitochondrial acetoacetyl-CoA thiolases by its chromatographic behaviour, kinetic characteristics and partial internal amino-acid sequences. The enzyme did not catalyse the cleavage of medium or long chain 3-oxoacyl-CoAs. The enzyme cross-reacted with polyclonal antibodies raised against cytosolic acetoacetyl-CoA thiolase. The latter property was exploited to confirm the peroxisomal localization of the novel thiolase in subcellular fractionation experiments. The peroxisomal acetoacetyl-CoA thiolase most probably catalyses the first reaction in peroxisomal cholesterol and dolichol synthesis. In addition, its presence in peroxisomes along with the other enzymes of the ketogenic pathway indicates that the ketogenic potential of peroxisomes needs to be re-evaluated. [source] Tailoring orthogonal proteomic routines to understand protein separation during ion exchange chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2008Rosa Cabrera Abstract Surface charge, molecular weight, and folding state are known to influence protein chromatographic behaviour onto ion exchangers. Experimentally, information related to such factors can be gathered via 2-DE methods. The application of 2-D PAGE under denaturing/reducing conditions was already shown to reveal separation trends within a large protein population from cell extracts. However, ion-exchange chromatography normally runs under native conditions. A tailored protocol consisting in a first separation based on IEF on ImmobilineTM strips under native conditions followed by a second dimension SDS-PAGE run was adopted. The chromatographic versus electrophoretic separation behaviours of two model proteins, thaumatin (TAU) and BSA, were compared to better understand which proteomic routine would be better suited to anticipate IEX chromatographic separations. It was observed that the information contained in the pI value obtained with the adapted 2-DE protocol showed better correlation with the IEX chromatographic behaviour. On the other hand, chromatographic separations performed in the presence of urea as a denaturant have demonstrated the potential influence of hydrodynamic radius/conformation on protein separation. Moreover, the information provided by such 2-D system correlated well with the chromatographic behaviour of an additional set of pure proteins. An initial prediction of protein ion-exchange chromatographic behaviour could be possible utilizing an experimental approach based on 2-DE running under milder chemical conditions. This technique provides information that more closely resembles the separation behaviour observed with a complex biotechnological feedstock. [source] Behaviour of carbamate pesticides in gas chromatography and their determination with solid-phase extraction and solid-phase microextraction as preconcentration stepsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16 2005Rita Carabias-Martínez Abstract This work reports a study of the chromatographic behaviour of seven carbamate pesticides (aldicarb, carbetamide, propoxur, carbofuran, carbaryl, methiocarb, and pirimicarb) by gas chromatography-mass spectrometry (GC-MS). Variables such as injector temperature, solvent, injection mode, and the degree of ageing of the chromatographic column were studied. One of the aims of this work was to achieve a controlled decomposition of carbamates by a solid-phase microextraction (SPME) preconcentration step with a polyacrylate fibre in order to obtain reproducible chromatographic signals of the degradation products. Optimisation of the SPME process was accomplished by means of experimental design. Several methods using ultrapure water were developed with different preconcentration configurations: SPME-GC-MS, SPE followed by SPME-GC-MS, and SPE plus GC-MS. For all the pesticides studied, method detection limit (MDL) values below 0.1 ,g L,1 were reached in at least one of the proposed configurations. [source] Characterisation of varnishes used in violins by pyrolysis-gas chromatography/mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2008Giuseppe Chiavari The correct characterisation and a detailed knowledge of the materials originally used in violin varnishes, like natural resins, is crucial for the conservation in museums and for a suitable restoration technique. The study presented here reports on the potential of pyrolysis (Py) coupled with gas chromatography (GC) and mass spectrometry (MS) for the identification of chemical markers of each resin; this tecnique is very sensitive and selective, it needs a small quantity of sample and does not require chemical treatments. To improve the chromatographic behaviour of polar compounds the derivatising agent tetramethylammonium hydroxide (TMAH) in combination with pyrolysis has been used, in the so-called TMAH thermochemolysis or thermally assisted hydrolysis and methylation (THM), or more simply pyrolysis-methylation. The natural resins studied were colophony, sandarac, manila copal, elemi, amber and benzoin, mainly composed of terpenic compounds, with the exception of the latter, composed of aromatic compounds. Many compounds were identified; in particular, methyl esters of resinous acids that, individually or in a group, can be used as chemical markers. However, through this technique it was not possible to distinguish between the sandarac and manila copal resins because their chromatographic behaviour is very similar. Finally, the procedure applied has been employed in the characterisation of original varnish samples. Copyright © 2008 John Wiley & Sons, Ltd. [source] Retention data from reverse-phase high-performance thin-layer chromatography in characterization of some bis-salicylic acid derivativesBIOMEDICAL CHROMATOGRAPHY, Issue 8 2009-Sekuli, Tatjana Djakovi Abstract The chromatographic behaviour of salicylic acid derivatives was investigated using reversed-phase high performance thin-layer chromatography (RP HPTLC) with methanol,water and dioxane,water binary mixtures as mobile phase in order to establish relationships between chromatographic data and selected physico-chemical parameters that are related to ADME (absorption, distribution, metabolism and elimination). Some of the investigated compounds were screened for antioxidant activity. Examination of chromatographic behaviour revealed a linear correlation between RM values and the volume fraction of mobile phase modifier. Obtained RM0 values were correlated with lipophilicity, solubility, human intestinal absorption, plasma-protein binding, and blood,brain barrier data. The comparison among chromatographic data obtained by two mobile phase was performed with a statistical technique, principle component analysis. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||