Search results for "Electrospray Ionization"
showing 10 items of 275 documents
Identification and cloning of odorant binding proteins from the scarab beetle Phyllopertha diversa.
1999
Abstract Wehave identified, cloned, and characterized two odorant binding proteins from the pale brown chafer, Phyllopertha diversa. One of the proteins (OBP1, 116 amino acids long) showed high amino acid identity (>90%) to two previously identified PBPs from scarab beetles. The second protein (OBP2) showed limited sequence similarity to lepidopteran and dipteran OBPs, but contained only 133 amino acids. Both proteins showed the occurrence of six highly conserved cysteines; electrospray mass spectral data suggested they are all bound in three disulfide bonds. During purification, OBP2 separated into several isoforms; N-terminal amino acid sequencing and electrospray ionization mass spectrom…
The metal binding abilities of Megathura crenulata metallothionein (McMT) in the frame of gastropoda MTs.
2011
Metallothioneins (MTs) are proteins that play a major role in metal homeostasis and/or detoxification in all kind of organisms. The MT gene/protein system of gastropod molluscs provides an invaluable model to study the diversification mechanisms that have enabled MTs to achieve metal-binding specificity through evolution. Most pulmonate gastropods, particularly terrestrial snails, harbor three paralogous isogenes encoding three MT isoforms with different metal binding preferences: the highly specific CdMT and CuMT isoforms, for cadmium and copper respectively, and the unspecific Cd/CuMT isoform. Megathura crenulata is a non-pulmonate gastropod in which only one MT isogene has so far been re…
Two new triterpenoid saponins fromPittosporum senaciaPutterlick (Pittosporaceae)
2012
From the branches of Pittosporum senacia Putterlick (Pittosporaceae), two new triterpenoid saponins, senaciapittosides A and B (1, 2), were isolated. Their structures were elucidated by extensive analysis of one- and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution electrospray ionization mass spectrometry (HR-ESIMS) and chemical evidence as 3-O-[β-d-glucopyranosyl-(1 2)]-[α-l-arabinopyranosyl-(1 3)]-[α-l-arabinofuranosyl-(1 4)]-β-d-glucuronopyranosyl oleanolic acid 28-O-β-d-glucopyranosyl ester (1) and 3-O-[β-d-glucopyranosyl-(1 2)]-[α-l-arabinopyranosyl-(1 3)]-[α-l-arabinofuranosyl-(1 4)]-β-d-glucuronopyranosyl-22-O-α-l-arabinopyranosyl-21-acetoxy R1-barrigen…
High-performance liquid chromatographic, capillary electrophoretic and capillary electrophoretic–electrospray ionisation mass spectrometric analysis …
2002
Systems for efficient separation of selected alkaloid groups by high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrophoresis coupled with electrospray ionisation mass spectrometry (CE-ESI-MS) are described. The optimized HPLC system was applied for the separation of 23 standard indole alkaloids as well as for qualitative and quantitative analyses of crude alkaloid extracts of Rauvolfia serpentina X Rhazya stricta hybrid cell cultures. The developed conditions for CE analysis proved to be efficient for separation of mixtures of standard indole and beta-carboline alkaloids. The described buffer system is also applicable in the combination of CE w…
Ion mobility spectrometry evaluation of cocaine occupational exposure in forensic laboratories
2014
An approach, based on ion mobility spectrometry (IMS) has been developed for the control of cocaine in air of the breathing zone of operators, in laboratory surfaces and in nasal mucus of employees to evaluate cocaine exposure in a forensic laboratory. The analytical methodology has been validated in terms of accuracy, precision and limits of detection and results obtained were statistically comparable with those obtained by liquid chromatography. Cocaine concentration in laboratory air increases from 100 ± 35 ng m(-3) of a normal day to 10,000 ng m(-3) during the manipulation of cocaine seizures. The occupational exposure limit (OEL) for cocaine has not been established which difficult the…
Cyclic Dinuclear Organotin Cations Stabilized by Bulky Substituents
2015
The syntheses of sterically congested 2,2-bis(diorganochloridostannyl)propane, Me2C(SnClR2)2 (1; R = CH(SiMe3)2), the related salts [cyclo-{Me2C(SnR2)2X}B(ArF)4] (2, X = Cl; 3, X = OAc; 4, X = OH; ArF = 3,5-(CF3)2C6H3), and the four-membered-ring cyclo-{Me2C(SnR2)2O} (5) are reported. The compounds have been characterized by elemental and EDX analyses, 1H, 11B, 13C, 19F, 29Si, and 119Sn NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analysis.
Toward multifunctional single-molecule magnets: characterization of dodecanuclear manganese complexes by electrospray ionization mass spectrometry.
2001
Single-molecule magnets (SMM) based on the dodecanuclear manganese complexes Mn12O12(RCOO)16 can be readily characterized by electrospray ionization mass spectrometry. This facilitates the synthesis of complex multifunctional molecules that have potential use in the organization of SMM into films or surfaces.
Fragmentations and reactions of the organophosphate insecticide Diazinon and its oxygen analog Diazoxon studied by electrospray ionization ion trap m…
2005
The fragmentations and reactions of Diazinon and related compounds have been studied by electrospray ionization ion trap mass spectrometry. Several novel fragmentation and rearrangements have been observed, including an intramolecular thiono-thiolo rearrangement. The stability, in the gas-phase, of the protomers of 2-isopropyl-4-methyl-6-pyrimidinol has been demonstrated. The complexity of the gas phase ion processes observed suggest that, at present, caution Should be exercised in using this approach for the analysis of environmental and other samples until our understanding of these processes increases considerably. (J Am Soc Mass Spectrom 2005, 16, 515-523) (c) 2005 American Society for …
Gas-phase ion chemistry of protonated melatonin
2009
The gas-phase ion chemistry of protonated melatonin has been investigated by mass spectrometric (MS) techniques involving chemical ionisation, fast atom bombardment and electrospray ionisation. Either naturally-occurring or collision-induced decomposition experiments have been carried out using side chain tetra-deuterium-labelled derivatives, as well as the corresponding N–D derivatives obtained by exchange with D2O. The analysis of experimental results allows definite pathways for the formation of the ion at m/z 174 to be assigned and sheds some more light on the overall fragmentation pathways. Experiments on labelled derivatives evidenced H–D scrambling processes during fragmentation.
Degrees of freedom effect on fragmentation in tandem mass spectrometry of singly charged supramolecular aggregates of sodium sulfonates
2012
The characteristic collision energy (CCE) to obtain 50% fragmentation of positively and negatively single charged noncovalent clusters has been measured. CCE was found to increase linearly with the degrees of freedom (DoF) of the precursor ion, analogously to that observed for synthetic polymers. This suggests that fragmentation behavior (e.g. energy randomization) in covalent molecules and clusters are similar. Analysis of the slope of CCE with molecular size (DoF) indicates that activation energy of fragmentation of these clusters (loss of a monomer unit) is similar to that of the lowest energy fragmentation of protonated leucine-enkephalin. Positively and negatively charged aggregates be…