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Journal of the American Society for Mass Spectrometry

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https://www.readbyqxmd.com/read/28447219/an-ethcd-based-method-for-discrimination-of-leucine-and-isoleucine-residues-in-tryptic-peptides
#1
Sergey S Zhokhov, Sergey V Kovalyov, Tatiana Yu Samgina, Albert T Lebedev
An EThcD-based approach for the reliable discrimination of isomeric leucine and isoleucine residues in peptide de novo sequencing procedure has been proposed. A multistage fragmentation of peptide ions was performed with Orbitrap Elite mass spectrometer in electrospray ionization mode. At the first stage, z-ions were produced by ETD or ETcaD fragmentation of doubly or triply charged peptide precursor ions. These primary ions were further fragmented by HCD with broad-band ion isolation, and the resulting w-ions showed different mass for leucine and isoleucine residues...
April 26, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28432656/collisional-cross-sections-with-t-wave-ion-mobility-spectrometry-without-experimental-calibration
#2
Daniel N Mortensen, Anna C Susa, Evan R Williams
A method for relating traveling-wave ion mobility spectrometry (TWIMS) drift times with collisional cross-sections using computational simulations is presented. This method is developed using SIMION modeling of the TWIMS potential wave and equations that describe the velocity of ions in gases induced by electric fields. The accuracy of this method is assessed by comparing the collisional cross-sections of 70 different reference ions obtained using this method with those obtained from static drift tube ion mobility measurements...
April 21, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28432655/direct-analysis-of-organic-compounds-in-liquid-using-a-miniature-photoionization-ion-trap-mass-spectrometer-with-pulsed-carrier-gas-capillary-inlet
#3
Xinqiong Lu, Quan Yu, Qian Zhang, Kai Ni, Xiang Qian, Fei Tang, Xiaohao Wang
A miniature ion trap mass spectrometer with capillary direct sampling and vacuum ultraviolet photoionization source was developed to conduct trace analysis of organic compounds in liquids. Self-aspiration sampling is available where the samples are drawn into the vacuum chamber through a capillary with an extremely low flow rate (less than 1 μL/min), which minimizes sample consumption in each analysis to tens of micrograms. A pulsed gas-assisted inlet was designed and optimized to promote sample transmission in the tube and facilitate the cooling of ions, thereby improving instrument sensitivity...
April 21, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28432654/laser-desorption-ionization-mass-spectrometric-imaging-of-endogenous-lipids-from-rat-brain-tissue-implanted-with-silver-nanoparticles
#4
Ludovic Muller, Kathrine Baldwin, Damon C Barbacci, Shelley N Jackson, Aurélie Roux, Carey D Balaban, Bruce E Brinson, Michael I McCully, Ernest K Lewis, J Albert Schultz, Amina S Woods
Mass spectrometry imaging (MSI) of tissue implanted with silver nanoparticulate (AgNP) matrix generates reproducible imaging of lipids in rodent models of disease and injury. Gas-phase production and acceleration of size-selected 8 nm AgNP is followed by controlled ion beam rastering and soft landing implantation of 500 eV AgNP into tissue. Focused 337 nm laser desorption produces high quality images for most lipid classes in rat brain tissue (in positive mode: galactoceramides, diacylglycerols, ceramides, phosphatidylcholines, cholesteryl ester, and cholesterol, and in negative ion mode: phosphatidylethanolamides, sulfatides, phosphatidylinositol, and sphingomyelins)...
April 21, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28432653/analyzing-glycopeptide-isomers-by-combining-differential-mobility-spectrometry-with-electron-and-collision-based-tandem-mass-spectrometry
#5
J Larry Campbell, Takashi Baba, Chang Liu, Catherine S Lane, J C Yves Le Blanc, James W Hager
Differential mobility spectrometry (DMS) has been employed to separate isomeric species in several studies. Under the right conditions, factors such as separation voltage, temperature, the presence of chemical modifiers, and residence time can combine to provide unique signal channels for isomeric species. In this study, we examined a set of glycopeptide isomers, MUC5AC-3 and MUC5AC-13, which bear an N-acetyl-galactosamine (GalNAc) group on either threonine-3 or threonine-13. When analyzed as a mixture, the resulting MS and MS/MS spectra yield fragmentation patterns that cannot discern these convolved species...
April 21, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28429299/participation-of-c-h-protons-in-the-dissociation-of-a-proton-deficient-dipeptide
#6
Damodar Koirala, Sabyasachy Mistry, Paul G Wenthold
The dissociation of anionic dipeptides Phe*Gly and GlyPhe*, where Phe* refers to sulfonated phenyl alanine, has been investigated by using ion trap mass spectrometry. The dipeptides undergo collision-induced dissociation (CID) to give the same products, indicating that they rearrange to a common structure before dissociation. The rearrangement does not occur with the dipeptide methyl esters. The structures of the b2 ions were investigated to determine the effect that having a remote, anionic site has on product formation...
April 20, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28429298/peter-john-derrick-1945-2017
#7
Margaret Sheil
No abstract text is available yet for this article.
April 20, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28425052/dmso-assisted-electrospray-ionization-for-the-detection-of-small-peptide-hormones-in-urine-by-dilute-and-shoot-liquid-chromatography-high-resolution-mass-spectrometry
#8
Péter Judák, Janelle Grainger, Catrin Goebel, Peter Van Eenoo, Koen Deventer
The mobile phase additive (DMSO) has been described as a useful tool to enhance electrospray ionization (ESI) of peptides and proteins. So far, this technique has mainly been used in proteomic/peptide research, and its applicability in a routine clinical laboratory setting (i.e., doping control analysis) has not been described yet. This work provides a simple, easy to implement screening method for the detection of doping relevant small peptides (GHRPs, GnRHs, GHS, and vasopressin-analogues) with molecular weight less than 2 kDa applying DMSO in the mobile phase...
April 19, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28421405/differential-fragmentation-of-mobility-selected-glycans-via-ultraviolet-photodissociation-and-ion-mobility-mass-spectrometry
#9
Kelsey A Morrison, Brian H Clowers
The alternative dissociation pathways initiated by ultraviolet photodissociation (UVPD) compared with collision-induced dissociation (CID) may provide useful diagnostic fragments for biomolecule identification, including glycans. However, underivatized glycans do not commonly demonstrate strong UV absorbance, resulting in low fragmentation yields for UVPD spectra. In contrast to UVPD experiments that leverage covalent modification of glycans, we detail the capacity of metal adduction to yield comparatively rich UVPD fragmentation patterns and enhance separation factors for an isomeric glycan set in a drift tube ion mobility system...
April 18, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28421404/characterization-of-zno-nanoparticles-using-superconducting-tunnel-junction-cryodetection-mass-spectrometry
#10
Logan D Plath, Zongyu Wang, Jiajun Yan, Krzysztof Matyjaszewski, Mark E Bier
Zinc oxide (ZnO) nanoparticles coated with either n-octylamine (OA) or α-amino poly(styrene-co-acrylonitrile) (PSAN) ligands (L) have been analyzed using laser desorption/ionization and matrix assisted laser desorption/ionization (MALDI) time-of-flight (TOF) superconducting tunnel junction (STJ) cryodetection mass spectrometry. STJ cryodetection has the advantage of high m/z detection and allows for the determination of average molecular weights and dispersities for 500-600 kDa ZnO-L nanoparticles. The ability to detect the relative energies deposited into the STJs has allowed for investigation of ZnO-L metastable fragmentation...
April 18, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28417307/investigating-differences-in-gas-phase-conformations-of-25-hydroxyvitamin-d3-sodiated-epimers-using-ion-mobility-mass-spectrometry-and-theoretical-modeling
#11
Christopher D Chouinard, Vinícius Wilian D Cruzeiro, Christopher R Beekman, Adrian E Roitberg, Richard A Yost
Drift tube ion mobility coupled with mass spectrometry was used to investigate the gas-phase structure of 25-hydroxyvitamin D3 (25OHD3) and D2 (25OHD2) epimers, and to evaluate its potential in rapid separation of these compounds. Experimental results revealed two distinct drift species for the 25OHD3 sodiated monomer, whereas only one of these conformations was observed for its epimer (epi25OHD3). The unique species allowed 25OHD3 to be readily distinguished, and the same pattern was observed for 25OHD2 epimers...
April 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28417306/a-focus-honoring-r-graham-cooks-election-to-the-national-academy-of-sciences
#12
Michael L Gross
No abstract text is available yet for this article.
April 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28417305/uncovering-structural-diversity-of-unsaturated-fatty-acyls-in-cholesteryl-esters-via-photochemical-reaction-and-tandem-mass-spectrometry
#13
Jia Ren, Elissia T Franklin, Yu Xia
Mass spectrometry analysis of cholesteryl esters (CEs) faces several challenges, with one of them being the determination of the carbon-carbon double bond (C=C) locations within unsaturated fatty acyl chains. Paternὸ-Büchi (PB) reaction, a photochemical reaction based on the addition of acetone to C=C, is capable of C=C location determination when coupled with tandem mass spectrometry (MS/MS). In this study, the PB reaction conditions were tailored for CEs and subsequent nanoelectrospray ionization (nanoESI)...
April 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28417304/2016-asms-workshop-review-next-generation-lc-ms-critical-insights-and-future-perspectives
#14
Hongying Gao, Alexander Makarov, Richard D Smith
No abstract text is available yet for this article.
April 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28411310/identifying-the-d-pentoses-using-water-adduction-to-lithium-cationized-molecule
#15
Matthew T Campbell, Dazhe Chen, Gary L Glish
A method has been developed that is capable of distinguishing an exhaustive list of underivatized D-pentoses with only a mass spectrometer. Electrospray ionization (ESI) of a solution containing a pentose and a lithium salt yields [Pentose + Li](+). These lithiated pentoses adduct water in a quadrupole ion trap. The reaction rate of water adduction is unique for several of the pentose isomers. Additionally, there are multiple potential gas-phase lithiation sites to form [Pentose + Li](+). A mixture of ions with at least one reactive (water adducting) and at least one unreactive (non-adducting) lithiation site is formed for each pentose...
April 14, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28409445/ion-mobility-spectrometry-high-resolution-ltq-orbitrap-mass-spectrometry-for-analysis-of-homemade-explosives
#16
Nathan Hagan, Ilana Goldberg, Adam Graichen, Amanda St Jean, Ching Wu, David Lawrence, Plamen Demirev
The detailed chemical characterization of homemade explosives (HMEs) and other chemicals that can mimic or mask the presence of explosives is important for understanding and improving the performance of commercial instrumentation used for explosive detection. To that end, an atmospheric-pressure drift tube ion mobility spectrometry (IMS) instrument has been successfully coupled to a commercial tandem mass spectrometry (MS) system. The tandem MS system is comprised of a linear ion trap and a high resolution Orbitrap analyzer...
April 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28405940/assessing-the-interplay-between-the-physicochemical-parameters-of-ion-pairing-reagents-and-the-analyte-sequence-on-the-electrospray-desorption-process-for-oligonucleotides
#17
Babak Basiri, Mandi M Murph, Michael G Bartlett
Alkylamines are widely used as ion-pairing agents during LC-MS of oligonucleotides. In addition to a better chromatographic separation, they also assist with the desorption of oligonucleotide ions into the gas phase, cause charge state reduction, and decrease cation adduction. However, the choice of such ion-pairing agents has considerable influence on the MS signal intensity of oligonucleotides as they can also cause significant ion suppression. Interestingly, optimal ion-pairing agents should be selected on a case by case basis as their choice is strongly influenced by the sequence of the oligonucleotide under investigation...
April 12, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28405939/simple-and-environmentally-friendly-fabrication-of-superhydrophobic-alkyl-ketene-dimer-coated-maldi-concentration-plates
#18
Joakim Romson, Johan Jacksén, Åsa Emmer
Here we present a method to manufacture peptide-concentrating MALDI-plates with alkyl ketene dimer (AKD) as a new superhydrophobic coating. The fabrication of the hydrophobic plates included application of AKD by airbrush, and negative contact printing to generate the concentration sites. Deposited sample droplets were contained within the prestructured sites, and self-adjusted onto the site if slightly misplaced. No AKD contamination was observed, and the plates could easily be cleaned and regenerated. The S/N values for four model peptides was about twice as high compared with a standard steel plate and a commercial concentration plate...
April 12, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28401433/nominal-mass
#19
LETTER
Athula B Attygalle, Julius Pavlov
The current IUPAC-recommended definition of the term "nominal mass," based on the most abundant naturally occurring stable isotope of an element, is flawed. We propose that Nominal mass should be defined as the sum of integer masses of protons and neutrons in any chemical species. In this way, all isotopes and isotopologues can be assigned a definitive identifier. Graphical Abstract ᅟ.
April 11, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28401432/feasibility-assessment-of-a-maldi-fticr-imaging-approach-for-the-3d-reconstruction-of-a-mouse-lung
#20
E Ellen Jones, Cristine Quiason, Stephanie Dale, Sheerin K Shahidi-Latham
Matrix assisted laser desorption ionization imaging mass spectrometry (MALDI IMS) has proven to be a quick, robust, and label-free tool to produce two-dimensional (2D) ion-density maps representing the distribution of a variety of analytes across a tissue section of interest. In addition, three-dimensional (3D) imaging mass spectrometry workflows have been developed that are capable of visualizing these same analytes throughout an entire volume of a tissue rather than a single cross-section. Until recently, the use of Fourier transform ion cyclotron resonance (FTICR) mass spectrometers for 3D volume reconstruction has been impractical due to software limitations, such as inadequate capacity to manipulate the extremely large data files produced during an imaging experiment...
April 11, 2017: Journal of the American Society for Mass Spectrometry
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