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Journal of the American Society for Mass Spectrometry

Dan Bee Kim, Sohee Yoon
Although the low temperature plasma mass spectrometry (LTP-MS) is widely used as an analysis tool for many biochemical samples, its application window is somehow limited to the analytes of low molecular mass and high volatility. For this reason, there have been attempts to enhance the ionization/desorption efficiencies with extra heating, for instance. In this study, another enhancement method was suggested using the photocatalytic nano-particles (NPs). In order to assess the NP effects on the LTP-MS, two fatty acid ethyl ester samples of ethyl myristate and ethyl palmitate were used, and the NP of titanium dioxide (TiO2 ) was mainly employed...
September 20, 2018: Journal of the American Society for Mass Spectrometry
Dilshadbek T Usmanov, Satoshi Ninomiya, Kenzo Hiraoka, Hiroshi Wada, Hiroshi Nakano, Masaya Matsumura, Sachiyo Sanada-Morimura, Hiroshi Nonami
In electrospray, excess charges are supplied to a sample solution by the occurrence of electrochemical reactions. Recently, different versions of electrospray, e.g., dielectric barrier electrospray ionization, inductive desorption electrospray ionization, and electrostatic-ionization driven by dielectric polarization, have been reported in which the sample solution was not in direct contact with the metal electrode but separated by dielectric materials. The objective of the current work is to elucidate the mechanism of dielectric barrier electrospray...
September 20, 2018: Journal of the American Society for Mass Spectrometry
Elahe Honarvar, Andre R Venter
It is frequently said that DESI-MS follows a similar ionization mechanism as ESI because of similarities usually observed in their respective mass spectra. However, practical use of DESI-MS for protein analysis is limited to proteins with lower molecular weights (< 25 kDa) due to a mass-dependent loss in signal intensity. Here we investigated commonly used volatile acids and their ammonium salt buffers for DESI-MS analysis of protein. We noticed that, surprisingly, some additives influence the analysis differently in DESI compared to ESI...
September 19, 2018: Journal of the American Society for Mass Spectrometry
Oliver Peetz, Nils Hellwig, Erik Henrich, Julija Mezhyrova, Volker Dötsch, Frank Bernhard, Nina Morgner
Native mass spectrometry is applied for the investigation of proteins and protein complexes worldwide. The challenge in native mass spectrometry is maintaining the features of the proteins of interest, such as oligomeric state, bound ligands, or the conformation of the protein complex, during transfer from solution to gas phase. This is an essential prerequisite to allow conclusions about the solution state protein complex, based on the gas phase measurements. Therefore, soft ionization techniques are required...
September 17, 2018: Journal of the American Society for Mass Spectrometry
Jeong Ju Park, Choong Sik Lee, Sang Yun Han
To understand the anomalous collision-induced dissociation (CID) behavior of the proton-bound Hoogsteen base pair of cytosine (C) and guanine (G), C:H+ ∙∙∙G, we investigated CID of a homologue series of proton-bound heterodimers of C, 1-methylcytosine, and 5-methylcytosine with G as a common base partner. The CID experiments were performed in an energy-resolved way (ER-CID) under both multiple and near-single collision conditions. The relative stabilities of the protonated complexes examined by ER-CID suggested that the proton-bound complexes produced by electrospray ionization in this study are proton-bound Hoogsteen base pairs...
September 13, 2018: Journal of the American Society for Mass Spectrometry
Pengyi Zhao, Travis White, R Graham Cooks, Qinghao Chen, Yong Liu, Hao Chen
Elucidation of ion dissociation patterns is particularly important to structural analysis by mass spectrometry (MS). However, typically, only the charged fragments from an ion dissociation event are detected in tandem MS experiments; neutrals are not identified. In recent years, we have developed an atmospheric pressure thermal dissociation (APTD) technique that can be applied to dissociate ions at atmosphere pressure and thus provide one way to characterize neutral fragments. In this paper, we focus on the detection of neutral CO resulting from amino acid and peptide ion dissociation...
September 11, 2018: Journal of the American Society for Mass Spectrometry
Lars Sørensen, Rune Salbo
Hydrogen deuterium exchange measured by mass spectrometry (HDX-MS) is a commonly used technique for studying the structural dynamics of proteins in solution. The first part of any bottom-up HDX-MS experiment is to identify the peptides generated from a digestion step. This requires manual inspection of the identified peptides to determine their use for HDX-MS analysis, which is a time-consuming task. Throughout the literature, there have been different approaches for removing peptides that do not yield quantifiable HDX information...
August 31, 2018: Journal of the American Society for Mass Spectrometry
Mark W Towers, Tamas Karancsi, Emrys A Jones, Steven D Pringle, Emmanuelle Claude
Desorption electrospray ionisation mass spectrometry imaging (DESI-MSI) is typically known for the ionisation of small molecules such as lipids and metabolites, in singly charged form. Here we present a method that allows the direct detection of proteins and peptides in multiply charged forms directly from tissue sections by DESI. Utilising a heated mass spectrometer inlet capillary, combined with ion mobility separation (IMS), the conditions with regard to solvent composition, nebulising gas flow, and solvent flow rate have been explored and optimised...
August 30, 2018: Journal of the American Society for Mass Spectrometry
Georgia C Boles, R R Wu, M T Rodgers, P B Armentrout
Deamidation of asparagine residues, one of the fastest known post-translational modifications in proteins, plays a significant role in various biological functions and degenerative, aging diseases. Here, we present a full description of deamidation (as well as other key dissociation processes) from protonated asparaginyl-alanine, H+ (AsnAla), by studying its kinetic energy-dependent threshold collision-induced dissociation (TCID) with Xe using a guided ion beam tandem mass spectrometer. Relative thresholds compare favorably with those acquired by sustained off-resonance irradiation-CID of H+ (AsnAla) with Ar in a Fourier transform ion cyclotron resonance mass spectrometer...
August 29, 2018: Journal of the American Society for Mass Spectrometry
Min Tao, Li Zhang, Yinlong Guo
A novel dual-channel enzymatic inhibition measurement (DEIM) method was developed to improve the repeatability with light/heavy isotope substrates, producing reliable relative standard deviations (< 3%) by employing acetylcholinesterase (AChE) as the model enzyme. The matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) was adapted for enzyme-inhibited method due to its good salt-tolerance and high throughput; meanwhile, dual-channel enzymatic reactions were performed to improve the repeatability of each well...
August 29, 2018: Journal of the American Society for Mass Spectrometry
Dong Sun, Chong Su, Yingze Liu, Xiangjun Meng, John Paul Fawcett, Yingjie Guo, Jingkai Gu
Prostaglandins (PGs) are biologically active metabolites of arachidonic acid containing 20 carbon atoms, a cyclic moiety, and two side chains (A and B) in common. The bioassay of PGs requires high sensitivity because of their low concentration in tissues and blood and has usually been carried out by electrospray ionization tandem mass spectrometry (ESI-MS/MS) in the negative ion mode. Chemical derivatization of PG carboxylic acid groups to introduce positive charge-carrying groups is an established strategy to improve the sensitivity and selectivity of such assays...
August 27, 2018: Journal of the American Society for Mass Spectrometry
Andrea F Lopez-Clavijo, Rian L Griffiths, Richard J A Goodwin, Helen J Cooper
Here, we present liquid extraction surface analysis (LESA) coupled with electron-induced dissociation (EID) mass spectrometry in a Fourier-transform ion cyclotron resonance mass spectrometer for the analysis of small organic pharmaceutical compounds directly from dosed tissue. First, the direct infusion electrospray ionisation EID and collision-induced dissociation (CID) behaviour of erlotinib, moxifloxacin, clozapine and olanzapine standards were compared. EID mass spectra were also compared with experimental or reference electron impact ionisation mass spectra...
August 27, 2018: Journal of the American Society for Mass Spectrometry
Cheryl Frankfater, Xuntian Jiang, Fong-Fu Hsu
In the preceding article "Characterization of Long-Chain Fatty Acid as N-(4-Aminomethylphenyl) Pyridinium Derivative by MALDI LIFT-TOF/TOF Mass Spectrometry" by Frankfater et al., errors in Figs. 2 and 3 have occurred. The legend (Fig. 2).
August 27, 2018: Journal of the American Society for Mass Spectrometry
Xiuting Chen, Qingnuan Li, Yu Gong
Ligated tetrapositive metal ions are rare gas-phase species which tend to form complexes with lower charges due to the high 4th ionization energies of metals. We report the observation of tetrapositive Zr(TMPDA)3 4+ and Zr(TMOGA)3 4+ complexes in the gas phase by electrospray ionization of Zr(ClO4 )4 /TMPDA and Zr(ClO4 )4 /TMOGA mixtures. The Zr4+ center in both complexes is coordinated by nine atoms from three neutral diamide ligands forming nine-coordinate twisted tricapped trigonal prismatic geometry on the basis of DFT calculations...
August 23, 2018: Journal of the American Society for Mass Spectrometry
Jessica N Rabuck-Gibbons, Jean M Lodge, Anna K Mapp, Brandon T Ruotolo
The kinase-inducible domain (KIX) of the transcriptional coactivator CBP binds multiple transcriptional regulators through two allosterically connected sites. Establishing a method for observing activator-specific KIX conformations would facilitate the discovery of drug-like molecules that capture specific conformations and further elucidate how distinct activator-KIX complexes produce differential transcriptional effects. However, the transient and low to moderate affinity interactions between activators and KIX are difficult to capture using traditional biophysical assays...
August 22, 2018: Journal of the American Society for Mass Spectrometry
L A Hamlow, Y Zhu, Zachary J Devereaux, N A Cunningham, G Berden, J Oomens, M T Rodgers
Modifications to a Paul-type quadrupole ion trap mass spectrometer providing optical access to the trapped ion cloud as well as hardware and software for coupling to a table-top IR optical parametric oscillator laser (OPO) are detailed. Critical experimental parameters for infrared multiple photon dissociation (IRMPD) on this instrument are characterized. IRMPD action spectra, collected in the hydrogen-stretching region with this instrument, complemented by spectra in the IR fingerprint region acquired at the FELIX facility, are employed to characterize the structures of the protonated forms of 2-thiouridine, [s2 Urd+H]+ , and 4-thiouridine, [s4 Urd+H]+ ...
August 22, 2018: Journal of the American Society for Mass Spectrometry
Janez Kovač, Matjaž Finšgar
The powerful nature of the secondary ion mass spectrometry (SIMS) technique was explored in order to analyse very thin surface layers that were self-assembled on steel material from acidic solution. These surface layers are adsorbed corrosion inhibitors. The SIMS technique proved useful to characterise the molecular structure and homogeneity of thin surface layers in the nanometre range of specific analytes on the metallic substrate. Using SIMS, the thermal stability of these layers was further investigated and the desorption energy at a certain temperature was determined, where special attention was devoted to the method's static limit...
August 17, 2018: Journal of the American Society for Mass Spectrometry
Ri Wu, Wei-Jing Wu, Ze Wang, Y-L Elaine Wong, Y-L Winnie Hung, H T Wong, Xiangfeng Chen, T-W Dominic Chan
Differential ion mobility spectrometry (DMS) spatially separates ions in the gas phase using the mobility differences of the ions under applied low and high electric fields. The use of DMS as an ion filter (or ion selector) prior to mass spectrometry analysis has been compromised by the limited ion transmission efficiency. This paper reports enhancement of the DMS-MS sensitivity and signal stability using a modified CaptiveSpray™ source. In terms of the ion sampling and transmission efficiency, the modified CaptiveSpray source swept ~ 89% of the ions generated by the tapered capillary through the DMS device (compared to ~ 10% with a conventional microspray source)...
August 16, 2018: Journal of the American Society for Mass Spectrometry
Benjamin E Draper, Staci N Anthony, Martin F Jarrold
An atmospheric pressure interface transports ions from ambient pressure to the low-pressure environment of a mass spectrometer. A capillary coupled to an ion funnel is widely used. However, conventional ion funnels do little to negate the large amount of energy picked up by high-mass ions from the gas flow through the capillary. There has been little work done on the effects of gas flow on ion transmission, and the previous studies have all been limited to low-mass, low-charge ions. In this work, we account for the effects of gas flow, diffusion, and electric fields (static and oscillating) on ion trajectories and use simulations to design a new hybrid ion funnel-ion carpet (FUNPET) interface that transmits a broad mass range with a single set of instrument conditions...
August 15, 2018: Journal of the American Society for Mass Spectrometry
Cathy Muste, Kevin G Owens
Current literature shows a gap for methods which can identify yeast sub-species (strains or serovars) in samples where there are no viable cells remaining. Presented here is a technique for the analysis of yeast supernatant, including solid phase extraction, data-dependent acquisition liquid chromatography/mass spectrometry (LC-MS), and two chemometric methods to identify and classify yeast strains. Five strains of Saccharomyces cerevisiae were successfully identified in various stages of growth. In addition, peptide/protein identification was performed, without the need for additional data acquisition...
August 13, 2018: Journal of the American Society for Mass Spectrometry
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