Considerations in experimental and theoretical collision cross-section measurements of small molecules using travelling wave ion mobility spectrometry-mass spectrometry

Knapman, Tom W.; Berryman, Joshua T.; Campuzano, Iain; Harris, Sarah A.; Ashcroft, Alison E.

doi:10.1016/j.ijms.2009.09.011

Cited by 76 publications

(76 citation statements)

References 34 publications

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“…Note here that the lack of observed separation in helium is primarily a result of the relatively high wave potential used in the simulations. Helium drift gas separations have been demonstrated previously for a first generation TWIMS instrument, which operates with lower wave potentials (Knapman et al 2010). For nitrogen and argon, the three regions of ion motion can be observed in all resolving power plots, with a well-defined change in magnitude occurring between ion surfing and initial roll-over.…”

Section: Separation Efficiency In Twimsmentioning

confidence: 83%

The influence of drift gas composition on the separation mechanism in traveling wave ion mobility spectrometry: insight from electrodynamic simulations

May

McLean

2013

Int. J. Ion Mobil. Spec.

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The influence of three different drift gases (helium, nitrogen, and argon) on the separation mechanism in traveling wave ion mobility spectrometry is explored through ion trajectory simulations which include considerations for ion diffusion based on kinetic theory and the electrodynamic traveling wave potential. The model developed for this work is an accurate depiction of a second-generation commercial traveling wave instrument. Three ion systems (cocaine, MDMA, and amphetamine) whose reduced mobility values have previously been measured in different drift gases are represented in the simulation model. The simulation results presented here provide a fundamental understanding of the separation mechanism in traveling wave, which is characterized by three regions of ion motion: (1) ions surfing on a single wave, (2) ions exhibiting intermittent roll-over onto subsequent waves, and (3) ions experiencing a steady state roll-over which repeats every few wave cycles. These regions of ion motion are accessed through changes in the gas pressure, wave amplitude, and wave velocity. Resolving power values extracted from simulated arrival times suggest that momentum transfer in helium gas is generally insufficient to access regions (2) and (3) where ion mobility separations occur. Ion mobility separations by traveling wave are predicted to be effectual for both nitrogen and argon, with slightly lower resolving power values observed for argon as a result of band-broadening due to collisional scattering. For the simulation conditions studied here, the resolving power in traveling wave plateaus between regions (2) and (3), with further increases in wave velocity contributing only minor improvements in separations.

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Section: Separation Efficiency In Twimsmentioning

confidence: 83%

The influence of drift gas composition on the separation mechanism in traveling wave ion mobility spectrometry: insight from electrodynamic simulations

May

McLean

2013

Int. J. Ion Mobil. Spec.

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“…In silico were calculated utilizing a modified version of the projection approximation script developed by the Ashcroft group [31,32]; the modified source code is available from https://github.com/tumbling-cross-section. Modifications to the original script included a change in the sweep patterns to a used a Fibonacci 'Pinecone' grid instead of the latitude-longitude scan [33] and the ability to use atomic radii of any value.…”

Section: Molecular Modellingmentioning

confidence: 99%

Distinct higher-order α-synuclein oligomers induce intracellular aggregation

Illes‐Toth

Ramos

Cappai

et al. 2015

Biochemical Journal

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Misfolding and aggregation of α-synuclein (α-syn) into Lewy bodies is associated with a range of neurological disorders, including Parkinson's disease (PD). The cell-to-cell transmission of α-syn pathology has been linked to soluble amyloid oligomer populations that precede Lewy body formation. Oligomers produced in vitro under certain conditions have been demonstrated to induce intracellular aggregation in cell culture models. In the present study, we characterize, by ESI-ion mobility spectrometry (IMS)-MS, a specific population of α-syn oligomers. These MS-compatible oligomers were compared with oligomers with known seeding and pore-forming capabilities and were shown to have the ability to induce intracellular aggregation. Each oligomer type was shown to have distinct epitope profiles that correlated with their toxic gain-of-function. Structurally, the MS compatible oligomers populated a range of species from dimers through to hexamers. Lower-order oligomers were structurally diverse and consistent with unstructured assemblies. Higher-order oligomers were shown to be compact with ring-like structures. The observation of this compact state may explain how this natively disordered protein is able to transfer pathology from cell to cell and avoid degradation by cellular proteases.

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“…[3][4][5][6][7][8][9][10][11] The principles of TWIMS have been described in more detail elsewhere. 2 However, in summary, the drift cell contains paired electrodes that create a pulsed voltage which carries the ions through the drift cell as a travelling wave.…”

Section: Eqn2mentioning

confidence: 99%

“…A graph is plotted of known CCS modified to account for reduced mass and charge, against effective drift time and from this the CCS of the analytes can be determined. Calibrants have included peptides 11,12,13 , tetraalkylammonium halides (TAAHs), and pharmaceutical compounds 5 with structures that are usually different to that of the analyte ion under investigation. There are several reports on the application of this method to the study of metabolites, 4,5 proteins and peptides.…”

Section: Eqn2mentioning

confidence: 99%