The Bush Lab is a research group in the Department of Chemistry and the Biological Physics, Structure & Design Program at the University of Washington. Our research focuses on the development and application of mass spectrometry and ion mobility spectrometry techniques to elucidate the structures and assembly of protein complexes and subcellular machines.
- Interested in joining the Bush Lab, click here.
Prof. Bush will present the following talks this January and February:
- Department of Chemistry, University of Alabama, Tuscaloosa, AL, 2/11/16.
- Department of Chemistry, Florida State University, Tallahassee, FL, 2/4/16.
- Department of Chemistry, University of Florida, Gainesville, FL, 2/3/16.
- Department of Chemistry, University of Oregon, Eugene, OR, 1/25/16.
- Society of Western Analytical Professors (SWAP), University of California, Riverside, CA, 1/29/16.
- Triangle Area Mass Spectrometry Discussion Group, NC, 1/13/16. (Link)
Ion mobility mass spectrometry of peptide, protein, and protein complex ions using a radio-frequency confining drift cell
Samuel J. Allen, Kevin Giles, Tony Gilbert, Matthew F. Bush. Analyst 2016, in press. (Link)
Ion mobility mass spectrometry experiments enable the characterization of mass, assembly, and shape of biological molecules and assemblies. Here, a new radio-frequency confining drift cell is characterized and used to measure the mobilities of peptide, protein, and protein complex ions. The new drift cell replaced the traveling-wave ion mobility cell in a Waters Synapt G2 HDMS. Methods for operating the drift cell and determining collision cross section values using this experimental set up are presented within the context of the original instrument control software. Collision cross sections for 349 cations and anions are reported, 155 of which are for ions that have not been characterized previously using ion mobility. The values for the remaining ions are similar to those determined using a previous radio-frequency confining drift cell and drift tubes without radial confinement. Using this device under 2 Torr of helium gas and an optimized drift voltage, denatured and native-like ions exhibited average apparent resolving powers of 14.2 and 16.5, respectively. For ions with high mobility, which are also low in mass, the apparent resolving power is limited by contributions from ion gating. In contrast, the arrival-time distributions of low-mobility, native-like ions are not well explained using only contributions from ion gating and diffusion. For those species, the widths of arrival-time distributions are most consistent with the presence of multiple structures in the gas phase.
Analysis of Native-Like Proteins and Protein Complexes Using Cation to Anion Proton Transfer Reactions (CAPTR). Kenneth J. Laszlo; Matthew F. Bush. J. Am. Soc. Mass Spectrom. 2015, in press. (Link)
Mass spectra of native-like protein complexes often exhibit narrow charge-state distributions, broad peaks, and contributions from multiple, coexisting species. These factors can make it challenging to interpret those spectra, particularly for mixtures with significant heterogeneity. Here we demonstrate the use of ion/ion proton transfer reactions to reduce the charge states of m/z-selected, native-like ions of proteins and protein complexes, a technique that we refer to as cation to anion proton transfer reactions (CAPTR). We then demonstrate that CAPTR can increase the accuracy of charge state assignments and the resolution of interfering species in native mass spectrometry. The CAPTR product ion spectra for pyruvate kinase exhibit ~30 peaks and enable unambiguous determination of the charge state of each peak, whereas the corresponding precursor spectra exhibit ~6 peaks and the assigned charge states have an uncertainty of ±3%. 15+ bovine serum albumin and 21+ yeast enolase dimer both appear near m/z 4450 and are completely unresolved in a mixture. After a single CAPTR event, the resulting product ions are baseline resolved. The separation of the product ions increases dramatically after each subsequent CAPTR event; 12 events resulted in a 3000-fold improvement in separation relative to the precursor ions. Finally, we introduce a framework for interpreting and predicting the figures of merit for CAPTR experiments. More generally, these results suggest that CAPTR strongly complements other mass spectrometry tools for analyzing proteins and protein complexes, particularly those in mixtures.
Prof. Bush is excited to present the following talks next month:
- Korean Society for Mass Spectrometry Conference, Busan, Korea, 8/20/15.
- POSTECH Ion Chemistry Mini-Symposium, Pohang, Korea, 8/17/15.
- Young Chemists Symposium, IUPAC World Chemistry Congress, Busan, Korea, 8/14/15. (9:40-10:00 in Hall 107)
- New Development in MS Fundamentals and Instrumentation Symposium, IUPAC World Chemistry Congress, Busan, Korea, 8/10/15. (11:35-11:55 in Hall 103)
Prof. Bush thanks the IUPAC-2015 Organizing Committee, the Korean Chemical Society, and the Korean Society for Mass Spectrometry for supporting various parts of this visit.
Collision cross section calibrants for negative ion mode traveling wave ion mobility-mass spectrometry. Jay G. Forsythe, Anton S. Petrov, Chelsea A. Walker, Samuel J. Allen, Jarrod S. Pellissier, Matthew F. Bush, Nicholas V. Hud, Facundo M. Fernández. Analyst 2015, 140, 6853-6861. (Link|PUBMED)
Abstract. Unlike traditional drift-tube ion mobility-mass spectrometry, traveling-wave ion mobility-mass spectrometry typically requires calibration in order to generate collision cross section (CCS) values. Although this has received a significant amount of attention for positive-ion mode analysis, little attention has been paid for CCS calibration in negative ion mode. Here, we provide drift-tube CCS values for [M − H]− ions of two calibrant series, polyalanine and polymalic acid, and evaluate both types of calibrants in terms of the accuracy and precision of the traveling-wave ion mobility CCS values that they produce.
- For a perspective on this work, please see the feature that appeared on the main page for NASA Astrobiology (Link)
Rachael (Rae) Eaton, a first year graduate student in the Bush Lab, was recently awarded a National Science Foundation Graduate Research Fellowship! From the NSF:
The NSF Graduate Research Fellowship Program recognizes and supports outstanding graduate students in NSF-supported science, technology, engineering, and mathematics disciplines who are pursuing research-based Master’s and doctoral degrees at accredited United States institutions. (For additional information, click here.)
Prof. Bush will present the following talks this Spring:
- Colorado Mass Spectrometry Discussion Group, Colorado State University, Fort Collins, CO, 4/8/15. (Link)
- Uppsala Conference on Electron Capture and Transfer Dissociation, Lake Arrowhead, CA, 3/22/15. (Link)
- Triangle Area Mass Spectrometry Discussion Group, NC, 3/18/15. (Link)
- Pittcon Conference, New Orleans, LA, 3/9/15. (Pittcon | Symposium)
Rachael (Rae) Eaton, a first year graduate student in the Bush Lab, was one of three graduate students selected to be the first-ever PNNL Graduate Fellows! From the UW Department of Chemistry announcement:
The PNNL Graduate Fellowship Program provides recipients with valuable research experiences complementary to their graduate education at the University of Washington. This program was recently established by the Department of Chemistry and Pacific Northwest National Laboratory with the goal of generating new opportunities for collaboration, accelerating progress in research areas of mutual interest, and strengthening existing ties between the Department and PNNL.
Congratulations to Ken Laszlo, who just passed his General Exam and has advanced to candidacy!