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Ion mobility spectrometry

Matthew T Campbell, Gary L Glish
Differential ion mobility spectrometry (DIMS) is capable of separating components of complex mixtures prior to mass spectrometric analysis, thereby increasing signal-to-noise and signal-to-background ratios on millisecond timescales. However, adding a DIMS device to the front end of a mass spectrometer can reduce the signal intensity of subsequent mass spectrometric analysis. This is a result, in part, of ions lost due to inefficient transfer of ions from the DIMS device through the aperture leading into the mass spectrometer...
October 17, 2016: Journal of the American Society for Mass Spectrometry
Delphine Vincent, Aaron Elkins, Mark R Condina, Vilnis Ezernieks, Simone Rochfort
Cow's milk is an important source of proteins in human nutrition. On average, cow's milk contains 3.5% protein. The most abundant proteins in bovine milk are caseins and some of the whey proteins, namely beta-lactoglobulin, alpha-lactalbumin, and serum albumin. A number of allelic variants and post-translationally modified forms of these proteins have been identified. Their occurrence varies with breed, individuality, stage of lactation, and health and nutritional status of the animal. It is therefore essential to have reliable methods of detection and quantitation of these proteins...
2016: PloS One
Yashodharani Vytla, Laurence Ambrose Angel
The Cu(II) and pH titrations of four structurally similar 2His-2Cys motif peptides were investigated by electrospray ionization - ion mobility - mass spectrometry. The results provided insight into the pH dependent redox processes that took place in solution and identified the number of inter- or intra-molecular disulfide bridges, the number of Cu(I) or Cu(II) ions, the deprotonation sites and likely Cu(I/II) coordination of the various products. Competitive Cu(II) titrations of binary peptide mixtures at pH 5 indicated which species would preferably bind Cu(I) ions over forming the intramolecular disulfide bridge...
October 14, 2016: Analytical Chemistry
Michael T Marty, Kin Kuan Hoi, Carol V Robinson
Membrane proteins play critical physiological roles and make up the majority of drug targets. Due to their generally low expression levels and amphipathic nature, membrane proteins represent challenging molecular entities for biophysical study. Mass spectrometry offers several sensitive approaches to study the biophysics of membrane proteins. By preserving noncovalent interactions in the gas phase and using collisional activation to remove solubilization agents inside the mass spectrometer, native mass spectrometry (MS) is capable of studying isolated assemblies that would be insoluble in aqueous solution, such as membrane protein oligomers and protein-lipid complexes...
October 13, 2016: Accounts of Chemical Research
Anna C Susa, Zijie Xia, Henry Y H Tang, John A Tainer, Evan R Williams
Factors that influence the charging of protein ions formed by electrospray ionization from aqueous solutions in which proteins have native structures and function were investigated. Protein ions ranging in molecular weight from 12.3 to 79.7 kDa and pI values from 5.4 to 9.6 were formed from different solutions and reacted with volatile bases of gas-phase basicities higher than that of ammonia in the cell of a Fourier-transform ion cyclotron resonance mass spectrometer. The charge-state distribution of cytochrome c ions formed from aqueous ammonium or potassium acetate is the same...
October 12, 2016: Journal of the American Society for Mass Spectrometry
Sergio Armenta, Miguel de la Guardia, Antonio Abad-Fuentes, Antonio Abad-Somovilla, Francesc A Esteve-Turrillas
Different highly selective sorbents have been evaluated for the treatment of food and biological samples to determine chloramphenicol residues by ion mobility spectrometry (IMS). Combination of a selective solid-phase extraction (SPE) and dispersive liquid-liquid microextraction allowed a highly sensitive determination of chloramphenicol in water, milk, honey, and urine samples. The performance of selective SPE supports such as immunoaffinity chromatography (IAC) and molecular imprinted polymers (MIP) have been compared in terms of selectivity, sensitivity, trueness, precision, and reusability...
October 12, 2016: Analytical and Bioanalytical Chemistry
Antonino Natalello, Carlo Santambrogio, Rita Grandori
Native mass spectrometry (MS) has become a central tool of structural proteomics, but its applicability to the peculiar class of intrinsically disordered proteins (IDPs) is still object of debate. IDPs lack an ordered tridimensional structure and are characterized by high conformational plasticity. Since they represent valuable targets for cancer and neurodegeneration research, there is an urgent need of methodological advances for description of the conformational ensembles populated by these proteins in solution...
October 11, 2016: Journal of the American Society for Mass Spectrometry
Katrina Brendle, Ulrike Schwarz, Patrick Jäger, Patrick Weis, Manfred M Kappes
We have combined ion mobility mass spectrometry with quantum chemical calculations to investigate the gas phase structures of multiply negatively charged oligomers of meso-tetra(4-sulfonatophenyl)metalloporphyrins comprising the divalent metal centers Zn(II), Cu(II) and Pd(II). Sets of candidate structures were obtained by geometry optimizations based on calculations at both the semiempirical PM7and DFT levels. The corresponding theoretical cross sections were calculated with the projection approximation and also with the trajectory method...
October 11, 2016: Journal of Physical Chemistry. A
Sibylle Pfammatter, Eric Bonneil, Pierre Thibault
Quantitative proteomics using isobaric reagents tandem mass tags (TMT) or isobaric tags for relative and absolute quantitation (iTRAQ) provide a convenient approach to compare changes in protein abundances across multiple samples. However, the analysis of complex protein digests by isobaric labeling can be undermined by the relative large proportion of co-selected peptide ions that lead to distorted reporter ion ratios and affect the accuracy and precision of quantitative measurements. Here, we investigated the use of high-field asymmetric waveform ion mobility spectrometry (FAIMS) in proteomic experiments to reduce sample complexity and improve protein quantification using TMT isobaric labeling...
October 10, 2016: Journal of Proteome Research
Jongcheol Seo, Stephan Warnke, Sandy Gewinner, Wieland Schöllkopf, Michael T Bowers, Kevin Pagel, Gert von Helden
The charge distribution in a molecule is crucial in determining its physical and chemical properties. Aminobenzoic acid derivatives are biologically active small molecules, which have two possible protonation sites: the amine (N-protonation) and the carbonyl oxygen (O-protonation). Here, we employ gas-phase infrared spectroscopy in combination with ion mobility-mass spectrometry and density functional theory calculations to unambiguously determine the preferred protonation sites of p-, m-, and o-isomers of aminobenzoic acids as well as their ethyl esters...
September 14, 2016: Physical Chemistry Chemical Physics: PCCP
Qian Zhang, Feng-Qing Yang, Liya Ge, Yuan-Jia Hu, Zhi-Ning Xia
Hydrophilic interaction liquid chromatography, an alternative liquid chromatography mode, is of particular interest in separating hydrophilic and polar ionic compounds. Compared with traditional liquid chromatography techniques, hydrophilic interaction liquid chromatography offers specific advantages mainly including: (1) relatively green and water-soluble mobile phase composition, which enhances the solubility of hydrophilic and polar ionic compounds; (2) no need for ion-pairing reagents and high content of organic solvent, which benefits mass spectrometry detection; (3) high orthogonality to reverse-phase liquid chromatography, well adapted to two-dimensional liquid chromatography for complicated samples...
September 15, 2016: Journal of Separation Science
Evaggelos Kiriazopoulos, Sabina Zaharaki, Ariadni Vonaparti, Panagiota Vourna, Eirini Panteri-Petratou, Dimitra Gennimata, Kara Lombardo, Irene Panderi
The use of cephalosporins during breast feeding raises several issues, including the risk of drug exposure through breast milk for the infant. In this article a hydrophilic interaction liquid chromatography/ positive ion electrospray mass spectrometric assay (HILIC/ESI-MS) was developed for the quantitation of cefuroxime, cefoxitin and cefazolin in breast milk and human plasma. The assay was based on the use of small sample size, 25 μL of biological samples, following acetonitrile precipitation of proteins and filtration that enabled injection into the HILIC/ESI-MS system...
October 7, 2016: Drug Testing and Analysis
Chrys Wesdemiotis
Multidimensional mass spectrometry interfaces a suitable ionization technique and mass analysis (MS) with tandem mass spectrometry (MS²) fragmentation and an orthogonal online separation method. Separation choices include liquid chromatography (LC) and ion mobility spectrometry (IMS), which disperse pre-ionization in the solution state or post-ionization in the gas phase, respectively. The MS step provides elemental composition information, while MS² exploits differences in the bond stabilities of a polymer, yielding connectivity and sequence information...
October 6, 2016: Angewandte Chemie
Alyssa Garabedian, David Butcher, Jennifer L Lippens, Jaroslava Miksovska, Prem P Chapagain, Daniele Fabris, Mark E Ridgeway, Melvin A Park, Francisco Fernandez-Lima
In the present work, the conformational dynamics and folding pathways of i-motif DNA were studied in solution and in the gas-phase as a function of the solution pH conditions using circular dichroism (CD), photoacoustic calorimetry analysis (PAC), trapped ion mobility spectrometry-mass spectrometry (TIMS-MS), and molecular dynamics (MD). Solution studies showed at thermodynamic equilibrium the existence of a two-state folding mechanism, whereas during the pH = 7.0 → 4.5 transition a fast and slow phase (ΔHfast + ΔHslow = 43 ± 7 kcal mol(-1)) with a volume change associated with the formation of hemiprotonated cytosine base pairs and concomitant collapse of the i-motif oligonucleotide into a compact conformation were observed...
September 29, 2016: Physical Chemistry Chemical Physics: PCCP
W B Struwe, C Baldauf, J Hofmann, P M Rudd, K Pagel
There has been increasing evidence that certain isomeric glycans can be separated efficiently by ion mobility-mass spectrometry when deprotonated ions are analyzed. To better understand the fundamentals behind these separations, we here investigate the impact of ionisation mode and adduct formation using IM-MS, density-functional theory and ab initio molecular dynamics.
October 11, 2016: Chemical Communications: Chem Comm
Lotta Turunen, Ulrike Warzok, Rakesh Puttreddy, Ngong Kodiah Beyeh, Christoph A Schalley, Kari Rissanen
Two [N⋅⋅⋅I(+) ⋅⋅⋅N] halogen-bonded dimeric capsules using tetrakis(3-pyridyl)ethylene cavitands with different lower rim alkyl chains are synthesized and analyzed in solution and the gas phase. These first examples of symmetrical dimeric capsules making use of the iodonium ion (I(+) ) as the main connecting module are characterized by (1) H NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), electrospray ionization mass spectrometry (ESI-MS), and ion mobility-mass spectrometry (TW-IMS) experiments...
October 6, 2016: Angewandte Chemie
Andrew J Creese, Helen J Cooper
High field asymmetric waveform ion mobility spectrometry (FAIMS) is well-established as a tool for separating peptide isomers (sequence inversions and post-translationally modified localization variants). Here, we demonstrate the FAIMS is able to differentiate cis and trans isomers of polyproline. Polyproline assumes an all-cis conformation-the PPI helix-in 1-propanol, and an all-trans conformation-the PPII helix-in aqueous solutions. Differentiation of these conformers may be achieved both through use of a cylindrical FAIMS device and a miniaturized ultrahigh field planar FAIMS device...
October 4, 2016: Journal of the American Society for Mass Spectrometry
Hwang Eui Cho, H Kang Min
A simple and accurate high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of N-(4-hydroxyphenyl)retinamide (fenretinide, 4-HPR) and its metabolites, 4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR) and N-(4-methoxyphenyl)retinamide (4-MPR), in human plasma. Plasma samples were prepared using protein precipitation with ethanol. Chromatographic separation of the three analytes and N-(4-ethoxyphenyl)retinamide (4-EPR), an internal standard, was achieved on a Zorbax SB-C18 column (3...
September 29, 2016: Journal of Pharmaceutical and Biomedical Analysis
Michael David Williams, Lingling Xian, Tait Huso, Jeong-Jin Park, David Huso, Leslie M Cope, David R Gang, William F Siems, Linda Resar, Raymond Reeves, Herbert H Hill
Because colorectal cancer (CRC) remains a leading cause of cancer mortality worldwide, more accessible screening tests are urgently needed to identify early-stage lesions. We hypothesized that highly sensitive, metabolic profile analysis of stool samples will identify metabolites associated with early-stage lesions and could serve as a noninvasive screening test. We therefore applied travelling wave ion mobility mass spectrometry (TWIMMS) coupled with ultra-performance liquid chromatography (UPLC) to investigate metabolic aberrations in stool samples in a transgenic model of pre-malignant polyposis aberrantly expressing the gene encoding the high mobility group A (Hmga1) chromatin remodeling protein...
October 4, 2016: Journal of Proteome Research
Yan Du, Yin-Jie Li, Xun-Xiu Hu, Xu Deng, Zeng-Ting Qian, Zheng Li, Meng-Zhe Guo, Dao-Quan Tang
As essential endogenous compounds, nucleobases and nucleosides fulfill various functions in living organisms. This work presents the development and validation of a new hydrophilic interaction liquid chromatography (HILIC) tandem mass spectrometry method for simultaneous quantification of 19 nucleobases and nucleosides in rat plasma. For the sample preparation, 15 kinds of protein precipitants were evaluated according to the chromatographic profile and ion response of analytes. The optimization of chromatographic separation was respectively performed using reversed-phase liquid chromatography (RPLC) and HILIC mode; each separation mode included two test columns with different stationary phases...
October 3, 2016: Biomedical Chromatography: BMC
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