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International Journal of Mass Spectrometry

Christopher D Chouinard, Vinicius Wilian D Cruzeiro, Robin H J Kemperman, Nicholas R Oranzi, Adrian E Roitberg, Richard A Yost
Ion mobility-mass spectrometry is a useful tool in separation of biological isomers, including clinically relevant analytes such as 25-hydroxyvitamin D3 (25OHD3) and its epimer, 3-epi-25-hydroxyvitamin D3 (epi25OHD3). Previous research indicates that these epimers adopt different gas-phase sodiated monomer structures, either the "open" or "closed" conformer, which allow 25OHD3 to be readily resolved in mixtures. In the current work, alternative metal cation adducts are investigated for their relative effects on the ratio of "open" and "closed conformers...
September 2018: International Journal of Mass Spectrometry
Sarah Rodriguez Castillo, Aude Simon, Christine Joblin
We present a detailed study of the main dehydrogenation processes of two dibenzopyrene cation (C24 H14 + ) isomers, namely dibenzo(a,e)pyrene (AE+ ) and dibenzo(a,l)pyrene (AL+ ). First, action spectroscopy under VUV photons was performed using synchrotron radiation in the 8-20 eV range. We observed lower dissociation thresholds for the non-planar molecule (AL+ ) than for the planar one (AE+ ) for the main dissociation pathways: H and 2H/H2 loss. In order to rationalize the experimental results, dissociation paths were investigated by means of density functional theory calculations...
June 2018: International Journal of Mass Spectrometry
Haopeng Xiao, Ju Eun Hwang, Ronghu Wu
Protein N-glycosylation is essential for mammalian cell survival and is well-known to be involved in many biological processes. Aberrant glycosylation is directly related to human disease including cancer and infectious diseases. Global analysis of protein N-glycosylation will allow a better understanding of protein functions and cellular activities. Mass spectrometry (MS)-based proteomics provides a unique opportunity to site-specifically characterize protein glycosylation on a large scale. Due to the complexity of biological samples, effective enrichment methods are critical prior to MS analysis...
June 2018: International Journal of Mass Spectrometry
Zachary M Smith, Vincent Steinmetz, Jonathan Martens, Jos Oomens, John C Poutsma
Infrared multiple photon dissociation spectroscopy was performed on protonated and cationized canavanine (Cav), a non-protein amino acid oxy-analog of arginine. Infrared spectra in the XH stretching region (3000 - 4000 cm-1 ) were obtained at the Centre Laser Infrarouge d'Orsay (CLIO) facility. Comparison of the experimental infrared spectra with scaled harmonic frequencies at the B3LYP/6-31+G(d,p) level of theory indicates that canavanine is in a canonical neutral form in CavH+ , CavLi+ , and CavNa+ ; therefore, these cations are charge-solvated structures...
June 2018: International Journal of Mass Spectrometry
Kendra J Adams, Natalie F Smith, Cesar E Ramirez, Francisco Fernandez-Lima
In the present work, the potential for rapid, targeted analysis of hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) in diluted human blood plasma using liquid chromatography coupled with trapped ion mobility spectrometry and TOF high resolution mass spectrometry (LC-TIMS-TOF MS) was evaluated. Experimental OH-PCB collisional cross section (CCSN2 ) and gas-phase candidate structures (<3% error) are reported for the first time and used, in addition to the LC retention time and accurate m / z , as OH-PCB identification features in order to increase the detection selectivity...
April 2018: International Journal of Mass Spectrometry
Jody C May, Ewa Jurneczko, Sarah M Stow, Isabel Kratochvil, Stefan Kalkhof, John A McLean
In this study, a commercial uniform field drift tube ion mobility-mass spectrometer (IM-MS) was utilized to measure the gas-phase conformational populations of three well-studied proteins: ubiquitin (8566 Da), cytochrome c (12,359 Da), and myoglobin in both apo and holo forms (16,951 and 17,567 Da, respectively) in order to evaluate the use of this technology for broadscale structural proteomics applications. Proteins were electrosprayed from either acidic organic (pH ~3) or aqueous buffered (pH ~6.6) solution phase conditions, which generated a wide range of cation charge states corresponding to both extended (unfolded) and compact (folded) gas-phase conformational populations...
April 2018: International Journal of Mass Spectrometry
David J Foreman, Stella K Betancourt, Alice L Pilo, Scott A McLuckey
Novel peptide ion chemistry associated with gold (I) cationization is described. Cation switching ion/ion reactions, involving gold dichloride reagent anion, [AuCl2 ]- , are used to replace protons with a gold (I) cation on a polypeptide. Collision induced dissociation of aurated, lysine-containing peptides results in the elimination of gold hydride and ammonia, generating a [M - H - NH3 ]+ oxidized species. The oxidized product is likely a cyclic iminium ion. This fragmentation pathway is specific to lysine side-chains as polypeptides containing arginine or histidine in the absence of lysine were not observed to form the oxidized product...
April 2018: International Journal of Mass Spectrometry
Michael Nshanian, Rajeswari Lakshmanan, Hao Chen, Rachel R Ogorzalek Loo, Joseph A Loo
Trifluoroacetic acid (TFA) is often used as a mobile phase modifier to enhance reversed phase chromatographic performance. TFA adjusts solution pH and is an ion-pairing agent, but it is not typically suitable for electrospray ionization-mass spectrometry (ESI-MS) and liquid chromatography/MS (LC/MS) because of its significant signal suppression. Supercharging agents elevate peptide and protein charge states in ESI, increasing tandem MS (MS/MS) efficiency. Here, LC/MS protein supercharging was effected by adding agents to LC mobile phase solvents...
April 2018: International Journal of Mass Spectrometry
Sung-Gun Park, Gordon A Anderson, James E Bruce
Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is well-renowned for its ultrahigh resolving power and mass measurement accuracy. As with other types of analytical instrumentation, achievable signal-to-noise ratio (S/N) is an important analytical figure of merit with FTICR-MS. S/N can be improved with higher magnetic fields and longer time-domain signal acquisition periods. However, serial signal averaging of spectra or time-domain signals acquired with multiple ion populations is most commonly used to improve S/N...
April 2018: International Journal of Mass Spectrometry
Aivett Bilbao, Bryson C Gibbons, Gordon W Slysz, Kevin L Crowell, Matthew E Monroe, Yehia M Ibrahim, Richard D Smith, Samuel H Payne, Erin S Baker
The mass accuracy and peak intensity of ions detected by mass spectrometry (MS) measurements are essential to facilitate compound identification and quantitation. However, high concentration species can yield erroneous results if their ion intensities reach beyond the limits of the detection system, leading to distorted and non-ideal detector response (e.g. saturation), and largely precluding the calculation of accurate m/z and intensity values. Here we present an open source computational method to correct peaks above a defined intensity (saturated) threshold determined by the MS instrumentation such as the analog-to-digital converters or time-to-digital converters used in conjunction with time-of-flight MS...
April 2018: International Journal of Mass Spectrometry
Ying Zhu, Rui Zhao, Paul D Piehowski, Ronald J Moore, Sujung Lim, Victoria J Orphan, Ljiljana Paša-Tolić, Wei-Jun Qian, Richard D Smith, Ryan T Kelly
One of the greatest challenges for mass spectrometry (MS)-based proteomics is the limited ability to analyze small samples. Here we investigate the relative contributions of liquid chromatography (LC), MS instrumentation and data analysis methods with the aim of improving proteome coverage for sample sizes ranging from 0.5 ng to 50 ng. We show that the LC separations utilizing 30-μm- i.d. columns increase signal intensity by >3-fold relative to those using 75-μm- i.d. columns, leading to 32% increase in peptide identifications...
April 2018: International Journal of Mass Spectrometry
Michael T Costanzo, Jared J Boock, Robin H J Kemperman, Michael S Wei, Christopher R Beekman, Richard A Yost
Miniaturized mass spectrometry (MMS) is optimal for a wide variety of applications that benefit from field-portable instrumentation. Like MMS, field asymmetric ion mobility spectrometry (FAIMS) has proven capable of providing in situ analysis, allowing researchers to bring the lab to the sample. FAIMS compliments MMS very well, but has the added benefit of operating at atmospheric pressure, unlike MS. This distinct advantage makes FAIMS uniquely suited for portability. Since its inception, FAIMS has been envisioned as a field-portable device, as it affords less expense and greater simplicity than many similar methods...
November 2017: International Journal of Mass Spectrometry
Christelle Guillermier, J Collin Poczatek, Walter R Taylor, Matthew L Steinhauser
In the field of secondary ion mass spectrometry at nanometer scale (NanoSIMS), configuration of parallel detectors to routinely measure isotope ratios in sub-100 nm domains brings classical stable isotope tracer studies from the whole tissue level down to the suborganelle level. Over the past decade, the marriage of stable isotope tracers with NanoSIMS has been applied to a range of fundamental biological questions that were largely inaccessible by other means. Although multiplexed measurement of different stable isotope tracers is feasible, in practice there remains a gap in the current analytical capacity to efficiently measure stable isotopes commonly utilized in tracer studies...
November 2017: International Journal of Mass Spectrometry
Zhe Zhang, Richard W Vachet
The gas phase structures of several proteins have been studied by electron transfer dissociation (ETD) with and without prior collisional heating after electrospraying these proteins from native-like solutions into a quadrupole ion trap mass spectrometer. Without prior collisional heating, we find that ETD fragmentation is mostly limited to regions of the protein that are not spanned by the salt bridges known to form in solution. When protein ions are collisionally heated before ETD, new product ions are observed, and in almost all cases, these new ions arise from protein regions that are spanned by the salt bridges...
September 2017: International Journal of Mass Spectrometry
Natália E C de Almeida, Thanh D Do, Nichole E LaPointe, Michael Tro, Stuart C Feinstein, Joan-Emma Shea, Michael T Bowers
The early oligomerization of amyloid β -protein (A β ) is a crucial step in the etiology of Alzheimer's disease (AD), in which soluble and highly neurotoxic oligomers are produced and accumulated inside neurons. In search of therapeutic solutions for AD treatment and prevention, potent inhibitors that remodel A β assembly and prevent neurotoxic oligomer formation offer a promising approach. In particular, several polyphenolic compounds have shown anti-aggregation properties and good efficacy on inhibiting oligomeric amyloid formation...
September 2017: International Journal of Mass Spectrometry
Hanliu Wang, Qin Shu, Don L Rempel, Carl Frieden, Michael L Gross
Bacteria within Curli biofilms are protected from environmental pressures (e.g., disinfectants, antibiotics), and this is responsible for intractable infections. Understanding aggregation of the major protein component of Curli, CsgA, may uncover disease-associated amyloidogenesis mechanisms. Here, we report the application of pulsed hydrogen-deuterium exchange and mass spectrometry (HDX-MS) to study CsgA aggregation, thereby obtaining region-specific information. By following time-dependent peptide signal depletion, presumably a result of insoluble fibril formation, we acquired sigmoidal profiles that are specific for regions (region-specific) of the protein...
September 2017: International Journal of Mass Spectrometry
Shuai Niu, Byung Chul Kim, Carol A Fierke, Brandon T Ruotolo
Histone deacetylase 8, part of a broad class of proteins responsible for regulating transcription and many other cellular processes and directly linked to a host of human disease through its mis-function, has been canonically described as a zinc-based mettalo-enzyme for many years. Recent evidence, however, has linked this protein to iron incorporation, loaded through transient interactions with the poly r(C)-binding protein 1, a metallo-chaperone and storage protein. In this report, we construct and deploy an electrospray-mass spectrometry based assay aimed at quantifying the interaction strength between these two weakly-associated proteins, as well as the zinc and iron associated form of the histone deacetylase...
September 2017: International Journal of Mass Spectrometry
Amanda L Patrick, Adam P Cismesia, Larry F Tesler, Nicolas C Polfer
The effects of electrospray ionization (ESI) solvent and source temperature on the relative abundance of the preferred solution-phase (N-protonated; i.e. amine) versus preferred gas-phase (O-protonated; i.e., acid) isomers of p-aminobenzoic acid (PABA) were investigated. When PABA was electrosprayed from protic solvents (i.e., methanol/water), the infrared multiple photon dissociation (IRMPD) spectrum recorded was consistent with that for O-protonation, according to both calculations and previous studies. When aprotic solvent (i...
July 2017: International Journal of Mass Spectrometry
Yanyan Lu, Yan Jiang, Tatiana Prokaeva, Lawreen H Connors, Catherine E Costello
Immunoglobulin light chain amyloidosis (AL) is a plasma cell disorder characterized by overproduction and deposition of monoclonal immunoglobulin (Ig) light chains (LC) or variable region fragments as amyloid fibrils in various organs and tissues. Much clinical evidence indicates that patients with AL amyloidosis sustain cardiomyocyte impairment and suffer from oxidative stress. We seek to understand the underlying biochemical pathways whose disruption or amplification during sporadic or sustained disease states leads to harmful physiological consequences and to determine the detailed structures of intermediates and products that serve as signposts for the biochemical changes and represent potential biomarkers...
May 2017: International Journal of Mass Spectrometry
Andrew G Elliott, Samuel I Merenbloom, Satrajit Chakrabarty, Evan R Williams
A new charge detection mass spectrometer that combines array detection and electrostatic ion trapping to repeatedly measure the masses of single ions is described. This instrument has four detector tubes inside an electrostatic ion trap with conical electrodes (cone trap) to provide multiple measurements of an ion on each pass through the trap resulting in a signal gain over a conventional trap with a single detection tube. Simulations of a cone trap and a dual ion mirror trap design indicate that more passes through the trap per unit time are possible with the latter...
March 2017: International Journal of Mass Spectrometry
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