Collision Cross Sections and Ion Structures: Development of a General Calculation Method via High-quality Ion Mobility Measurements and Theoretical Modeling. Jong Wha Lee, Kimberly L. Davidson, Matthew F. Bush, Hugh I. Kim. Analyst 2017, in press. (Link)
Ion mobility mass spectrometry (IM-MS) has become an important tool for the structural investigation of ions in the gas phase. Accurate theoretical evaluation of ion collision cross sections (CCSs) is essential for the effective application of IM-MS in structural studies. However, current theoretical tools have limitations in accurately describing a broad range of ions from small molecules to macromolecules. Continue reading
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Congratulations to Kim Davidson, whose research is featured on the cover of the special issue on “New developments and applications of mass spectrometry methods for studying non-covalent protein interactions”.
Nonspecific Aggregation in Native Electrokinetic Nanoelectrospray Ionization. Kimberly L. Davidson; Derek R. Oberreit; Christopher J. Hogan; Matthew F. Bush. Int. J. Mass Spectrom. 2017, 420, 35–42. (Link | Cover)
Effects of Charge State, Charge Distribution, and Structure on the Ion Mobility of Protein Ions in Helium Gas: Results from Trajectory Method Calculations. Kenneth J. Laszlo, Matthew F. Bush. J. Phys. Chem. A, 2017, in press. (Link)
Collision cross section (Ω) values of gas-phase ions of proteins and protein complexes are used to probe the structures of the corresponding species in solution. Ions of many proteins exhibit increasing Ω-values with increasing charge state but most Ω-values calculated for protein ions have used simple collision models that do not explicitly account for charge. Here we use a combination of ion mobility mass spectrometry experiments with helium gas and trajectory method calculations to characterize the extents to which increases in experimental Ω-values with increasing charge state may be attributed to increased momentum transfer concomitant with enhanced long-range interactions between the protein ion and helium atoms. Continue reading
Matt Bush presented the following talks at the ACS Fall National Meeting in Washington DC, where he also received the Arthur F. Findeis Award for Achievements by a Young Analytical Scientist.
ANYL 269: Interpreting the collision cross sections of proteins: Insights from ion mobility, unfolding, and folding of ions in the gas phase, as a part of the Analytical Division Award Symposium.
PHYS 322: Effects of charge state on the structures of protein ions: Results from cation-to-anion proton-transfer reactions (CAPTR), as a part of the symposium on Gaseous Ion Chemistry & Surface Reactions.
Interpreting the Collision Cross Sections of Native-Like Protein Ions: Insights from Cation-to-Anion Proton-Transfer Reactions. Kenneth J. Laszlo, Matthew F. Bush. Anal. Chem. 2017, DOI: 10.1021/acs.analchem.7b01474. (Link)
The effects of charge state on structures of native-like cations of serum albumin, streptavidin, avidin, and alcohol dehydrogenase were probed using cation-to-anion proton-transfer reactions (CAPTR), ion mobility, mass spectrometry, and complementary energy-dependent experiments. The CAPTR products all have collision cross-section (Ω) values that are within 5.5% of the original precursor cations. The first CAPTR event for each precursor yields products Continue reading
Structural Dynamics of Native-Like Ions in the Gas Phase: Results from Tandem Ion Mobility of Cytochrome c. Samuel J. Allen, Rachel M. Eaton, Matthew F. Bush. Anal. Chem. 2017, DOI: 10.1021/acs.analchem.7b01234. (Link)
Ion mobility (IM) is a gas-phase separation technique that is used to determine the collision cross sections of native-like ions of proteins and protein complexes, which are in turn used as restraints for modeling the structures of those analytes in solution. Here, we evaluate the stability of native-like ions using tandem IM experiments implemented using structures for lossless ion manipulations (SLIM). In this implementation of tandem IM, ions undergo a first dimension of IM up to a switch that is used to selectively transmit ions of a desired mobility. Selected ions are accumulated in a trap and then released after a delay to initiate the second dimension of IM. For delays ranging from 16 to 33 231 ms, Continue reading
Effects of Solution Structure on the Folding of Lysozyme Ions in the Gas-Phase. Kenneth J. Laszlo, Eleanor B. Munger, Matthew F. Bush. J. Phys. Chem. B 2017, 121, 2759–2766. (Link)
The fidelity between the structures of proteins in solution and protein ions in the gas phase is critical to experiments that use gas-phase measurements to infer structures in solution. Here we generate ions of lysozyme, a 129-residue protein whose native tertiary structure contains four internal disulfide bonds, from three solutions that preserve varying extents of the original native structure. We then use cation-to-anion proton-transfer reactions (CAPTR) to reduce the charge states of those ions in the gas phase and ion mobility to probe their structures. The collision cross section (Ω) distributions of Continue reading