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Journal of the American Society for Mass Spectrometry

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https://www.readbyqxmd.com/read/28213728/fourier-transform-ion-cyclotron-resonance-mass-spectrometry-at-the-cyclotron-frequency
#1
Konstantin O Nagornov, Anton N Kozhinov, Yury O Tsybin
The phenomenon of ion cyclotron resonance allows for determining mass-to-charge ratio, m/z, of an ensemble of ions by means of measurements of their cyclotron frequency, ω c . In Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), the ω c quantity is usually unavailable for direct measurements: the resonant state is located close to the reduced cyclotron frequency (ω+), whereas the ω c and the corresponding m/z values may be calculated via theoretical derivation from an experimental estimate of the ω+ quantity...
February 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28211014/comprehensive-peptide-ion-structure-studies-using-ion-mobility-techniques-part-1-an-advanced-protocol-for-molecular-dynamics-simulations-and-collision-cross-section-calculation
#2
Samaneh Ghassabi Kondalaji, Mahdiar Khakinejad, Amirmahdi Tafreshian, Stephen J Valentine
Collision cross-section (CCS) measurements with a linear drift tube have been utilized to study the gas-phase conformers of a model peptide (acetyl-PAAAAKAAAAKAAAAKAAAAK). Extensive molecular dynamics (MD) simulations have been conducted to derive an advanced protocol for the generation of a comprehensive pool of in-silico structures; both higher energy and more thermodynamically stable structures are included to provide an unbiased sampling of conformational space. MD simulations at 300 K are applied to the in-silico structures to more accurately describe the gas-phase transport properties of the ion conformers including their dynamics...
February 16, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28211013/electrostatic-forces-as-dominant-interactions-between-proteins-and-polyanions-an-esi-ms-study-of-fibroblast-growth-factor-binding-to-heparin-oligomers
#3
Burcu Baykal Minsky, Paul L Dubin, Igor A Kaltashov
The interactions between fibroblast growth factors (FGFs) and their receptors (FGFRs) are facilitated by heparan sulfate (HS) and heparin (Hp), highly sulfated biological polyelectrolytes. The molecular basis of FGF interactions with these polyelectrolytes is highly complex due to the structural heterogeneity of HS/Hp, and many details still remain elusive, especially the significance of charge density and minimal chain length of HS/Hp in growth factor recognition and multimerization. In this work, we use electrospray ionization mass spectrometry (ESI MS) to investigate the association of relatively homogeneous oligoheparins (octamer, dp8, and decamer, dp10) with acidic fibroblast growth factor (FGF-1)...
February 16, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28197928/enhanced-reactivity-in-nucleophilic-acyl-substitution-ion-ion-reactions-using-triazole-ester-reagents
#4
Jiexun Bu, Zhou Peng, Feifei Zhao, Scott A McLuckey
The acyl substitution reactions between 1-hydroxy-7-aza-benzotriazole (HOAt)/1-hydroxy-benzotriazole (HOBt) ester reagents and nucleophilic side chains on peptides have been demonstrated in the gas phase via ion/ion reactions. The HOAt/HOBt ester reagents were synthesized in solution and ionized via negative nano-electrospray ionization. The anionic reagents were then reacted with doubly protonated model peptides containing amines, guanidines, and imidazoles in the gas phase. The complexes formed in the reaction cell were further probed with ion trap collision induced dissociation (CID) yielding either a covalently modified analyte ion or a proton transfer product ion...
February 14, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28197927/thermodynamics-and-reaction-mechanisms-of-decomposition-of-the-simplest-protonated-tripeptide-triglycine-a-guided-ion-beam-and-computational-study
#5
Abhigya Mookherjee, Michael J Van Stipdonk, P B Armentrout
We present a thorough characterization of fragmentations observed in threshold collision-induced dissociation (TCID) experiments of protonated triglycine (H(+)GGG) with Xe using a guided ion beam tandem mass spectrometer (GIBMS). Kinetic energy-dependent cross-sections for 10 ionic products are observed and analyzed to provide 0 K barriers for six primary products: [b2](+), [y1 + 2H](+), [b3](+), CO loss, [y2 + 2H](+), and [a1](+); three secondary products: [a2](+), [a3](+), and [y2 + 2H - CO](+); and two tertiary products: high energy [y1 + 2H](+) and [a2 - CO](+) after accounting for multiple ion-molecule collisions, internal energy of reactant ions, unimolecular decay rates, competition between channels, and sequential dissociations...
February 14, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28197926/outstanding-jasms-manuscript-reviewers-2015-2016
#6
EDITORIAL
Joseph A Loo, Joyce L Neff
No abstract text is available yet for this article.
February 14, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28194741/deciphering-the-biophysical-effects-of-oxidizing-sulfur-containing-amino-acids-in-interferon-beta-1a-using-ms-and-hdx-ms
#7
Damian J Houde, George M Bou-Assaf, Steven A Berkowitz
Introduction of a chemical change to one or more amino acids in a protein's polypeptide chain can result in various effects on its higher-order structure (HOS) and biophysical behavior (or properties). These effects range from no detectable change to significant structural or conformational alteration that can greatly affect the protein's biophysical properties and its resulting biological function. The ability to reliably detect the absence or presence of such changes is essential to understanding the structure-function relationship in a protein and in the successful commercial development of protein-based drugs (biopharmaceuticals)...
February 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28194740/potential-of-burkholderia-seminalis-tc3-4-2r3-as-biocontrol-agent-against-fusarium-oxysporum-evaluated-by-mass-spectrometry-imaging
#8
Francisca Diana da Silva Araújo, Welington Luiz Araújo, Marcos Nogueira Eberlin
Species of genus Burkholderia display different interaction profiles in the environment, causing either several diseases in plants and animals or being beneficial to some plants, promoting their growth, and suppressing phytopathogens. Burkholderia spp. also produce many types of biomolecules with antimicrobial activity, which may be commercially used to protect crops of economic interest, mainly against fungal diseases. Herein we have applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate secondary metabolites produced by B...
February 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28194739/jack-throck-watson-may-2-1939-september-3-2016
#9
Gavin E Reid, O David Sparkman
No abstract text is available yet for this article.
February 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28194738/collidoscope-an-improved-tool-for-computing-collisional-cross-sections-with-the-trajectory-method
#10
Simon A Ewing, Micah T Donor, Jesse W Wilson, James S Prell
Ion mobility-mass spectrometry (IM-MS) can be a powerful tool for determining structural information about ions in the gas phase, from small covalent analytes to large, native-like or denatured proteins and complexes. For large biomolecular ions, which may have a wide variety of possible gas-phase conformations and multiple charge sites, quantitative, physically explicit modeling of collisional cross sections (CCSs) for comparison to IMS data can be challenging and time-consuming. We present a "trajectory method" (TM) based CCS calculator, named "Collidoscope," which utilizes parallel processing and optimized trajectory sampling, and implements both He and N2 as collision gas options...
February 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28194737/regio-selective-intramolecular-hydrogen-deuterium-exchange-in-gas-phase-electron-transfer-dissociation
#11
Yoshitomo Hamuro
Protein backbone amide hydrogen/deuterium exchange mass spectrometry (HDX-MS) typically utilizes enzymatic digestion after the exchange reaction and before MS analysis to improve data resolution. Gas-phase fragmentation of a peptic fragment prior to MS analysis is a promising technique to further increase the resolution. The biggest technical challenge for this method is elimination of intramolecular hydrogen/deuterium exchange (scrambling) in the gas phase. The scrambling obscures the location of deuterium...
February 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28194736/fischer-indole-synthesis-in-the-gas-phase-the-solution-phase-and-at-the-electrospray-droplet-interface
#12
Ryan M Bain, Stephen T Ayrton, R Graham Cooks
Previous reports have shown that reactions occurring in the microdroplets formed during electrospray ionization can, under the right conditions, exhibit significantly greater rates than the corresponding bulk solution-phase reactions. The observed acceleration under electrospray ionization could result from a solution-phase, a gas-phase, or an interfacial reaction. This study shows that a gas-phase ion/molecule (or ion/ion) reaction is not responsible for the observed rate enhancement in the particular case of the Fischer indole synthesis...
February 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28194735/assigning-peptide-disulfide-linkage-pattern-among-regio-isomers-via-methoxy-addition-to-disulfide-and-tandem-mass-spectrometry
#13
Kirt L Durand, Lei Tan, Craig A Stinson, Chasity B Love-Nkansah, Xiaoxiao Ma, Yu Xia
Pinpointing disulfide linkage pattern is critical in the characterization of proteins and peptides consisting of multiple disulfide bonds. Herein, we report a method based on coupling online disulfide modification and tandem mass spectrometry (MS/MS) to distinguish peptide disulfide regio-isomers. Such a method relies on a new disulfide bond cleavage reaction in solution, involving methanol as a reactant and 254 nm ultraviolet (UV) irradiation. This reaction leads to selective cleavage of a disulfide bond and formation of sulfenic methyl ester (-SOCH3) at one cysteine residue and a thiol (-SH) at the other...
February 13, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28155086/near-uv-photodissociation-of-tryptic-peptide-cation-radicals-scope-and-effects-of-amino-acid-residues-and-radical-sites
#14
Huong T H Nguyen, František Tureček
Peptide cation-radical fragment ions of the z-type, [(●)AXAR(+)], [(●)AXAK(+)], and [(●)XAR(+)], where X = A, C, D, E, F, G, H, K, L, M, N, P, Y, and W, were generated by electron transfer dissociation of peptide dications and investigated by MS(3)-near-ultraviolet photodissociation (UVPD) at 355 nm. Laser-pulse dependence measurements indicated that the ion populations were homogeneous for most X residues except phenylalanine. UVPD resulted in dissociations of backbone CO─NH bonds that were accompanied by hydrogen atom transfer, producing fragment ions of the [yn](+) type...
February 2, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28144898/ambient-ionization-mass-spectrometry-measurement-of-aminotransferase-activity
#15
Xin Yan, Xin Li, Chengsen Zhang, Yang Xu, R Graham Cooks
A change in enzyme activity has been used as a clinical biomarker for diagnosis and is useful in evaluating patient prognosis. Current laboratory measurements of enzyme activity involve multi-step derivatization of the reaction products followed by quantitative analysis of these derivatives. This study simplified the reaction systems by using only the target enzymatic reaction and directly detecting its product. A protocol using paper spray mass spectrometry for identifying and quantifying the reaction product has been developed...
January 31, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28144897/a-miniaturized-linear-wire-ion-trap-with-electron-ionization-and-single-photon-ionization-sources
#16
Qinghao Wu, Yuan Tian, Ailin Li, Derek Andrews, Aaron R Hawkins, Daniel E Austin
A linear wire ion trap (LWIT) with both electron ionization (EI) and single photon ionization (SPI) sources was built. The SPI was provided by a vacuum ultraviolet (VUV) lamp with the ability to softly ionize organic compounds. The VUV lamp was driven by a pulse amplifier, which was controlled by a pulse generator, to avoid the detection of photons during ion detection. Sample gas was introduced through a leak valve, and the pressure in the system is shown to affect the signal-to-noise ratio and resolving power...
January 31, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28127681/xylose-migration-during-tandem-mass-spectrometry-of-n-linked-glycans
#17
Elizabeth S Hecht, Philip L Loziuk, David C Muddiman
Understanding the rearrangement of gas-phase ions via tandem mass spectrometry is critical to improving manual and automated interpretation of complex datasets. N-glycan analysis may be carried out under collision induced (CID) or higher energy collision dissociation (HCD), which favors cleavage at the glycosidic bond. However, fucose migration has been observed in tandem MS, leading to the formation of new bonds over four saccharide units away. In the following work, we report the second instance of saccharide migration ever to occur for N-glycans...
January 26, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28127680/mass-spectral-library-quality-assurance-by-inter-library-comparison
#18
William E Wallace, Weihua Ji, Dmitrii V Tchekhovskoi, Karen W Phinney, Stephen E Stein
A method to discover and correct errors in mass spectral libraries is described. Comparing across a set of highly curated reference libraries compounds that have the same chemical structure quickly identifies entries that are outliers. In cases where three or more entries for the same compound are compared, the outlier as determined by visual inspection was almost always found to contain the error. These errors were either in the spectrum itself or in the chemical descriptors that accompanied it. The method is demonstrated on finding errors in compounds of forensic interest in the NIST/EPA/NIH Mass Spectral Library...
January 26, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28120300/effects-of-solvent-and-ion-source-pressure-on-the-analysis-of-anabolic-steroids-by-low-pressure-photoionization-mass-spectrometry
#19
Chengyuan Liu, Yanan Zhu, Jiuzhong Yang, Wan Zhao, Deen Lu, Yang Pan
Solvent and ion source pressure were two important factors relating to the photon induced ion-molecule reactions in low pressure photoionization (LPPI). In this work, four anabolic steroids were analyzed by LPPI mass spectrometry. Both the ion species present and their relative abundances could be controlled by switching the solvent and adjusting the ion source pressure. Whereas M(•+), MH(+), [M - H2O](+), and solvent adducts were observed in positive LPPI, [M - H](-) and various oxidation products were abundant in negative LPPI...
January 24, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28116700/proposed-confidence-scale-and-id-score-in-the-identification-of-known-unknown-compounds-using-high-resolution-ms-data
#20
Bertrand Rochat
High-resolution (HR) MS instruments recording HR-full scan allow analysts to go further beyond pre-acquisition choices. Untargeted acquisition can reveal unexpected compounds or concentrations and can be performed for preliminary diagnosis attempt. Then, revealed compounds will have to be identified for interpretations. Whereas the need of reference standards is mandatory to confirm identification, the diverse information collected from HRMS allows identifying unknown compounds with relatively high degree of confidence without reference standards injected in the same analytical sequence...
January 23, 2017: Journal of the American Society for Mass Spectrometry
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