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Juetten KJ, Sanders JD, Marty MT, Brodbelt JS. Combining Fourier Transform Ion Mobility with Charge Detection Mass Spectrometry for the Analysis of Multimeric Protein Complexes. Anal Chem 2025; 97:140-146. [PMID: 39810343 DOI: 10.1021/acs.analchem.4c03379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2025]
Abstract
Charge detection mass spectrometry (CDMS) allows direct mass measurement of heterogeneous samples by simultaneously determining the charge state and the mass-to-charge ratio (m/z) of individual ions, unlike conventional MS methods that use large ensembles of ions. CDMS typically requires long acquisition times and the collection of thousands of spectra, each containing tens to hundreds of ions, to generate sufficient ion statistics, making it difficult to interface with the time scales of online separation techniques such as ion mobility. Here, we demonstrate the application of Fourier transform multiplexing and drift tube ion mobility joined with Orbitrap-based CDMS for the analysis of multimeric protein complexes. Stepped frequency modulation was utilized to enable unambiguous frequency assignment during mobility sweeps and allow spectral averaging, which improves the accuracy and signal-to-noise of ion mobility spectra and CDMS measurements. Fourier transformation of the signal reveals the arrival times and collision cross sections of ions while simultaneously collecting charge information for thousands of individual ions. Combining Fourier transform multiplexing ion mobility and CDMS provides insight into each ion's size and mass while showcasing a potential solution to the duty cycle mismatch of online separation techniques in the single ion regime.
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Affiliation(s)
- Kyle J Juetten
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - James D Sanders
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Michael T Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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Cabrera ER, Schrader RL, Walker TE, Laganowsky A, Russell DH, Clowers BH. Nonlinear Frequency Modulation for Fourier Transform Ion Mobility Mass Spectrometry Improves Experimental Efficiency. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2024; 497:117197. [PMID: 38352886 PMCID: PMC10861183 DOI: 10.1016/j.ijms.2024.117197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2024]
Abstract
Through optimization of terminal frequencies and effective sampling rates, we have developed nonlinear sawtooth-shaped frequency sweeps for efficient Fourier transform ion mobility mass spectrometry (FT-IM-MS) experiments. This is in contrast to conventional FT-IM-MS experiments where ion gates are modulated according to a linear frequency sweep. Linear frequency sweeps are effective but can be hindered by the amount of useful signal obtained using a single sweep over a large frequency range imposed by ion gating inefficiencies, particularly small ion packets, and gate depletion. These negative factors are direct consequences of the inherently low gate pulse widths of high-frequency ion gating events, placing an upper bound on FT-IM-MS performance. Here, we report alternative ion modulation strategies. Sawtooth frequency sweeps may be constructed for the purpose of either extending high-SNR transients or conducting efficient signal-averaging experiments for low-SNR transients. The data obtained using this approach show high-SNR signals for a set of low-mass tetraalkylammonium salts (<1000 m/z) where resolving powers in excess of 500 are achieved. Data for low-SNR obtained for multimeric protein complexes streptavidin (53 kDa) and GroEL (800 kDa) also reveal large increases in the signal-to-noise ratio for reconstructed arrival time distributions.
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Affiliation(s)
- Elvin R. Cabrera
- Department of Chemistry, Washington State University, Pullman, WA 99164, United States
| | - Robert L. Schrader
- Department of Chemistry, Texas A&M University, College Station, TX 77843, United States
| | - Thomas E. Walker
- Department of Chemistry, Texas A&M University, College Station, TX 77843, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX 77843, United States
| | - David H. Russell
- Department of Chemistry, Texas A&M University, College Station, TX 77843, United States
| | - Brian H. Clowers
- Department of Chemistry, Washington State University, Pullman, WA 99164, United States
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Gurav AB, Webb IK. Charge Inversion Ion/Ion Reactions Coupled to Ion Mobility/Mass Spectrometry: Oligosaccharides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023. [PMID: 37167025 DOI: 10.1021/jasms.3c00093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Various ion mobility-based separation techniques and instruments have been recently developed to increase the operational resolution of ion mobility separations, especially of isomers and isobars. In addition to developments in instrumentation, different covalent and noncovalent derivatization techniques have helped achieve effective separations by magnifying minor differences in collision cross section. Among these methodologies is host-guest complex formation and, a new development presented herein, charge inversion ion-ion reactions coupled to ion mobility separations. We used these methods to enable formation of complexes between isomeric deprotonated oligosaccharides and alkaline earth metals (in solution) and alkaline earth metal-trisphenanthroline complexes (in vacuo), observing minor shifts in ion mobility arrival times for the charge inversion reaction products as well as unique mobility fingerprints indicative of separations of α/β anomers of disaccharides. For example, we have demonstrated separations between reducing disaccharides such as lactose and lactulose and nonreducing disaccharides. We also observed separations based on the pyranose/furanose configurations of the isomers. These results suggest the potential for ion/ion reactions to enable isomer separation of biomolecules from various compound classes using ion mobility-mass spectrometry (IM-MS).
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Affiliation(s)
- Ankita B Gurav
- Department of Chemistry and Chemical Biology, Indiana University─Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Ian K Webb
- Department of Chemistry and Chemical Biology, Indiana University─Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202, United States
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Lee J, Chai M, Bleiholder C. Differentiation of Isomeric, Nonseparable Carbohydrates Using Tandem-Trapped Ion Mobility Spectrometry-Mass Spectrometry. Anal Chem 2023; 95:747-757. [PMID: 36547374 PMCID: PMC10126951 DOI: 10.1021/acs.analchem.2c02844] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Carbohydrates play important roles in biological processes, but their identification remains a significant analytical problem. While mass spectrometry has increasingly enabled the elucidation of carbohydrates, current approaches are limited in their abilities to differentiate isomeric carbohydrates when these are not separated prior to tandem-mass spectrometry analysis. This analytical challenge takes on increased relevance because of the pervasive presence of isomeric carbohydrates in biological systems. Here, we demonstrate that TIMS2-MS2 workflows enabled by tandem-trapped ion mobility spectrometry-mass spectrometry (tTIMS/MS) provide a general approach to differentiate isomeric, nonseparated carbohydrates. Our analysis shows that (1) cross sections measured by TIMS are sufficiently precise and robust for ion identification; (2) fragment ion cross sections from TIMS2 analysis can be analytically exploited to identify carbohydrate precursors even if the precursor ions are not separated by TIMS; (3) low-abundant fragment ions can be exploited to identify carbohydrate precursors even if the precursor ions are not separated by IMS. (4) MS2 analysis of fragment ions produced by TIMS2 can be used to validate and/or further characterize carbohydrate structures. Taken together, our analysis underlines the opportunities that tandem-ion mobility spectrometry/MS methods offer for the characterization of mixtures of isomeric carbohydrates.
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Affiliation(s)
- Jusung Lee
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA
| | - Mengqi Chai
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA
| | - Christian Bleiholder
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390, USA
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4390, USA
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Butalewicz JP, Sanders JD, Clowers BH, Brodbelt JS. Improving Ion Mobility Mass Spectrometry of Proteins through Tristate Gating and Optimization of Multiplexing Parameters. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:101-108. [PMID: 36469482 DOI: 10.1021/jasms.2c00274] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Coupling drift tube ion mobility (IM) to Fourier transform mass spectrometry (FT-MS) affords the opportunity for gas-phase separation of ions based on size and conformation with high-resolution mass analysis. However, combining IM and FT-MS is challenging because ions exit the drift tube on a much faster time scale than the rate of mass analysis. Fourier transform (FT) and Hadamard transform multiplexing methods have been implemented to overcome the duty-cycle mismatch, offering new avenues for obtaining high-resolution, high-mass-accuracy analysis of mobility-selected ions. The gating methods used to integrate the drift tube with the FT mass analyzer discriminate against the transmission of large, low-mobility ions owing to the well-known gate depletion effect. Tristate gating strategies have been shown to increase ion transmission for drift tube IM-FT-MS systems through implementation of dual ion gating, controlling the quantity and timing of ions through the drift tube to reduce losses of slow-moving ions. Here we present an optimized set of multiplexing parameters for tristate gating ion mobility of several proteins on an Orbitrap mass spectrometer and further report parameters for increased ion transmission and mobility resolution as well as decreased experimental times from 15 min down to 30 s. On average, peak intensities in the arrival time distributions (ATDs) for ubiquitin increased 2.1× on average, while those of myoglobin increased by 1.5× with a resolving power increase on average of 11%.
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Affiliation(s)
- Jamie P Butalewicz
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - James D Sanders
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Brian H Clowers
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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Cabrera ER, Clowers BH. Considerations for Generating Frequency Modulation Waveforms for Fourier Transform-Ion Mobility Experiments. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:1858-1864. [PMID: 36066398 PMCID: PMC10370403 DOI: 10.1021/jasms.2c00168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
By casting the information regarding an ion population's mobility in the frequency domain, the coupling of time-dispersive ion mobility techniques is now imminently compatible with slower mass analyzers such as ion traps. Recent reports have detailed the continued progress toward maximizing the efficiency of the Fourier transform ion mobility-mass spectrometry (FT-IM-MS) experiments, but few reports have outlined the intersection between the practical considerations of implementation against the theoretical limits imposed by traditional signal processing techniques. One of the important concerns for Fourier-based multiplexing experiments is avoiding signal aliasing as a product of undersampled signals that may occur during data acquisition. In addition to traditional considerations such as detector sampling frequency, the limitations (i.e., maximum measurable drift time) imposed by experimental mass scan duration and the frequency sweep used for ion gate modulation must also be assessed. This work aims to connect the fundamental underpinnings of FT-IM-MS experiments and the associated experimental parameters that are encountered when coupling the comparatively fast separations in the mobility domain with the slower m/z scanning common for ion-trap mass analyzers. In addition to stating the relevant theory that applies to the FT-IM-MS experiment, this report highlights how aliased signals will manifest post Fourier transform in reconstructed arrival time distributions and calculated mobilities.
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Affiliation(s)
- Elvin R. Cabrera
- Department of Chemistry, Washington State University, Pullman, WA 99164, United States
| | - Brian H. Clowers
- Department of Chemistry, Washington State University, Pullman, WA 99164, United States
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Ma S, Chen F, Zhang M, Yuan H, Ouyang G, Zhao W, Zhang S, Zhao Y. Carboxyl-Based CPMP Tag for Ultrasensitive Analysis of Disaccharides by Negative Tandem Mass Spectrometry. Anal Chem 2022; 94:9557-9563. [PMID: 35759693 DOI: 10.1021/acs.analchem.2c00287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Here, we develop a sensitive method for glucose-containing disaccharide analysis by 1-(4-carboxyphenyl)-3-methyl-5-pyrazolone (CPMP) derivatization using mass spectrometry. The intense anion of [M - H]- (m/z 759) was observed for CPMP-labeled disaccharides in a negative mode. After derivatization, its sensitivity was significantly increased with the limits of detection (LODs) and limits of quantification (LOQ) ranging from 3.90 to 8.67 ng L-1 and 12.99 to 28.92 ng L-1, respectively. During CID-MS/MS analysis, the fragment patterns of CPMP derivatized disaccharides in the negative mode were simpler and clearer than their counterparts in a positive mode, which further could be applied to distinct and relatively quantitative isomeric disaccharides with ultrahigh sensitivity and good reproducibility. The great linear relationships could be achieved under wider concentration ratios from 0.01 to 20 compared to the previous report. Eventually, the developed methodology was applicable to identify isomeric disaccharides in beers. No sucrose was discovered. All beers contain 1,4- and 1,6-linked disaccharides. Some of them also have a mixture of 1,2- and 1,3-linked disaccharides. Through the integration of statistical analysis, beers with different production processes were finally discriminated, and the relative quantification of isomaltose and maltose was realized. In general, this method is sensitive, fast, and reliable for the discrimination and relative quantification of isomeric disaccharides in complex matrices. This study provides a new idea for the structural analysis of oligosaccharides in food, plants, and animals and an important theoretical basis for the exploration of new functions of oligosaccharides.
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Affiliation(s)
- Shanshan Ma
- College of Chemistry, Zhengzhou University, Henan 450001, China
| | - Fangya Chen
- School of Ecology and Environment, Zhengzhou University, Henan 450001, China
| | - Meng Zhang
- College of Chemistry, Zhengzhou University, Henan 450001, China
| | - Hang Yuan
- College of Chemistry, Zhengzhou University, Henan 450001, China
| | - Gangfeng Ouyang
- College of Chemistry, Zhengzhou University, Henan 450001, China.,KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China
| | - Wuduo Zhao
- College of Chemistry, Zhengzhou University, Henan 450001, China
| | - Shusheng Zhang
- College of Chemistry, Zhengzhou University, Henan 450001, China
| | - Yufen Zhao
- College of Chemistry, Zhengzhou University, Henan 450001, China.,Institute of Drug Discovery Technology, Ningbo University, Ningbo 315211, China
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Cabrera ER, Clowers BH. Synchronized Stepped Frequency Modulation for Multiplexed Ion Mobility Measurements. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:557-564. [PMID: 35108007 PMCID: PMC9264663 DOI: 10.1021/jasms.1c00365] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Implementation of frequency-encoded multiplexing for ion mobility spectrometry (e.g., Fourier transform ion mobility spectrometry (FT-IMS)) has facilitated the direct coupling of drift tube ion mobility instrumentation with ion-trap mass analyzers despite their duty cycle mismatch. Traditionally, FT-IMS experiments have been carried out to utilize continuous linear frequency sweeps that are independent of the scan rate of the ion-trap mass analyzer, thus creating a situation where multiple frequencies are swept over two sequential mass scans. This in turn creates a degree of ambiguity in which the ion current derived from a single modulation frequency cannot be assigned to a single data point in the frequency-modulated signal. In an effort to eliminate this ambiguity, this work describes a discrete stepwise function to modulate the ion gates of the IMS while synchronization between the generated frequencies and the scan rate of the linear ion trap is achieved. While the number of individual frequencies used in the stepped frequency sweeps is less than in continuous linear modulation experiments, there is no loss in performance and high levels of precision are maintained across differing combinations of terminal frequencies and scan lengths. Furthermore, the frequency-scan synchronization enables further data-processing techniques such as linear averaging of the frequency modulated signal to drastically improve signal-to-noise ratio for both high and low intensity analytes.
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