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Smith RD. Large Individual Ion FTICR Measurements from the Mid-1990s Using Reactions for Charge Determination Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:803-812. [PMID: 37021701 DOI: 10.1021/jasms.2c00329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This article discusses from a personal and present-day perspective the first studies of large highly charged individual molecular ions that were conducted using electrospray ionization with Fourier transform ion cyclotron resonance MS in the mid-1990s. These studies are distinguished from Current Charge Detection Mass Spectrometry (CDMS) primarily by their use of individual ion charge state changes due to reactions for accurate charge determination. This work describes the key differences in technologies and methods with present CDMS and the likely implications of these differences. I comment on surprising individual ion behavior observed in some measurements involving increases in charge state, as well as their possible basis, and also briefly discuss the potential utility of the reaction-based mass measurement approach used in the context of what might more globally be referred to as "Charge Determination Mass Spectrometry".
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Affiliation(s)
- Richard D Smith
- Pacific Northwest National Laboratory Richland, Washington 99352 United States
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2
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Miller ZM, Harper CC, Lee H, Bischoff AJ, Francis MB, Schaffer DV, Williams ER. Apodization Specific Fitting for Improved Resolution, Charge Measurement, and Data Analysis Speed in Charge Detection Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:2129-2137. [PMID: 36173188 PMCID: PMC10389282 DOI: 10.1021/jasms.2c00213] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Short-time Fourier transforms with short segment lengths are typically used to analyze single ion charge detection mass spectrometry (CDMS) data either to overcome effects of frequency shifts that may occur during the trapping period or to more precisely determine the time at which an ion changes mass or charge, or enters an unstable orbit. The short segment lengths can lead to scalloping loss unless a large number of zero-fills are used, making computational time a significant factor in real-time analysis of data. Apodization specific fitting leads to a 9-fold reduction in computation time compared to zero-filling to a similar extent of accuracy. This makes possible real-time data analysis using a standard desktop computer. Rectangular apodization leads to higher resolution than the more commonly used Gaussian or Hann apodization and makes it possible to separate ions with similar frequencies, a significant advantage for experiments in which the masses of many individual ions are measured simultaneously. Equally important is a >20% increase in S/N obtained with rectangular apodization compared to Gaussian or Hann, which directly translates to a corresponding improvement in accuracy of both charge measurements and ion energy measurements that rely on the amplitudes of the fundamental and harmonic frequencies. Combined with computing the fast Fourier transform in a lower-level language, this fitting procedure eliminates computational barriers and should enable real-time processing of CDMS data on a laptop computer.
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Affiliation(s)
- Zachary M. Miller
- College of Chemistry, University of California, Berkeley, California, 94720-1460, United States
| | - Conner C. Harper
- College of Chemistry, University of California, Berkeley, California, 94720-1460, United States
| | - Hyuncheol Lee
- College of Chemistry, University of California, Berkeley, California, 94720-1460, United States
- California Institute for Quantitative Biosciences, University of California, Berkeley, California 94720-1460, United States
| | - Amanda J. Bischoff
- College of Chemistry, University of California, Berkeley, California, 94720-1460, United States
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720, United States
| | - Matthew B. Francis
- College of Chemistry, University of California, Berkeley, California, 94720-1460, United States
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratories, Berkeley, California 94720, United States
| | - David V. Schaffer
- College of Chemistry, University of California, Berkeley, California, 94720-1460, United States
| | - Evan R. Williams
- College of Chemistry, University of California, Berkeley, California, 94720-1460, United States
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3
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Sutton JM, El Zahar NM, Bartlett MG. Oligonucleotide Anion Adduct Formation Using Negative Ion Electrospray Ion-Mobility Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:497-508. [PMID: 33476148 DOI: 10.1021/jasms.0c00380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Improving the mobile phase of electrospray oligonucleotides has been a major focus in the field of oligonucleotides. These improved mobile phases should reduce the charge state envelope of oligonucleotides coupled with electrospray ionization, which is key to reducing spectral complexity and increasing sensitivity. Traditional mobile phase compositions with fluorinated alcohol and alkylamine, like hexafluoroisopropanol (HFIP) and triethylamine (TEA), have a large amount of cationic adduction and many charge states. Utilizing different fluorinated alcohol and alkylamine combinations, like nonafluoro-tert-butyl alcohol (NFTB) and octylamine (OA), can selectively reduce the charge states analyzed. Other classes of biomolecules have been analyzed with anionic salts to stabilize complexes, increase the molecular peak detection, and even provide unique structural information about these molecules; however, there have been no studies using anionic salts with oligonucleotides. Our experiments systematically study the stability and binding of ammonium anionic salt. We show that anions selectively bind low charge states of these oligonucleotides. Ion-mobility measurements are made to determine the collision cross section (CCS) of these oligonucleotides with anion adduction. We utilize both a nucleic acid exact hard sphere simulation (EHSS) calibration and a protein calibration. We are able to show that NFTB/OA is a good choice for the study of oligonucleotides with reduced charge states for the binding of anionic salts and the determination of CCS using ion mobility.
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Affiliation(s)
- J Michael Sutton
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 250 West Green Street, Athens, Georgia 30602-2352, United States
| | - Noha M El Zahar
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 250 West Green Street, Athens, Georgia 30602-2352, United States
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Ain Shams University, Organization of African Unity Street, Abassia, Cairo 11566, Egypt
- Medicinal Chemistry Department, Faculty of Pharmacy, King Salman International University, Ras-Sedr, South Sinai Governorate 46612, Egypt
| | - Michael G Bartlett
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 250 West Green Street, Athens, Georgia 30602-2352, United States
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Sutton JM, Bartlett MG. Modeling cationic adduction of oligonucleotides using electrospray desorption ionization. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8696. [PMID: 31834644 DOI: 10.1002/rcm.8696] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/06/2019] [Accepted: 12/07/2019] [Indexed: 06/10/2023]
Abstract
RATIONALE Cationic adduction causes poor sensitivity and increases spectral complexity during mass spectral analysis of oligonucleotides and alkylamines are used to reduce this adduction. It is unclear the effect of the physiochemical properties of the alkylamines on the reduction of the cationic adduction. METHODS All samples were directly infused into a Synapt G2 HDMS quadrupole time-of-flight (TOF) hybrid mass spectrometer in negative ion electrospray ionization mode through the native built-in fluidics system. The infusion flow rate was set to 50 μL/min. The TOFMS tuning parameters were as follows: capillary voltage -2.0 kV, cone voltage 25 V, extraction cone voltage 2 V, source temperature 125°C, desolvation temperature 450°C, cone gas flow rate 0 L/h, and desolvation gas (nitrogen) flow rate 1000 L/h. RESULTS A quantitative model was created to predict the optimized alkylamine for MS analysis, while a qualitative model was generated to explain the most important physiochemical properties: proton affinity (13.83%), gas-phase basicity (11.79%), pKa (11.47%), boiling point (10.73%), MW (10.3%), Henry's Law Constant (9.56%), and partition coefficient (logP) (9.44%). The quantitative model was applied to RNA (microRNA) and a phosphorothioate and predicts the trend of cationic adduction. CONCLUSIONS Two models are described to understand the physiochemical properties that contribute to the adduction and to provide users a quick mathematical tool to predict the best choice of alkylamine to lower cationic adduction and decrease spectral complexity while enhancing sensitivity.
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Affiliation(s)
- J Michael Sutton
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, 250 West Green Street, Athens, GA, 30602-2352, USA
| | - Michael G Bartlett
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, 250 West Green Street, Athens, GA, 30602-2352, USA
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Harper CC, Elliott AG, Oltrogge LM, Savage DF, Williams ER. Multiplexed Charge Detection Mass Spectrometry for High-Throughput Single Ion Analysis of Large Molecules. Anal Chem 2019; 91:7458-7465. [PMID: 31082222 DOI: 10.1021/acs.analchem.9b01669] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Applications of charge detection mass spectrometry (CDMS) for measuring the masses of large molecules, macromolecular complexes, and synthetic polymers that are too large or heterogeneous for conventional mass spectrometry measurements are made possible by weighing individual ions in order to avoid interferences between ions. Here, a new multiplexing method that makes it possible to measure the masses of many ions simultaneously in CDMS is demonstrated. Ions with a broad range of kinetic energies are trapped. The energy of each ion is obtained from the ratio of the intensity of the fundamental to the second harmonic frequencies of the periodic trapping motion making it possible to measure both the m/ z and charge of each ion. Because ions with the exact same m/ z but with different energies appear at different frequencies, the probability of ion-ion interference is significantly reduced. We show that the measured mass of a protein complex consisting of 16 protomers, RuBisCO (517 kDa), is not affected by the number of trapped ions with up to 21 ions trapped simultaneously in these experiments. Ion-ion interactions do not affect the ion trapping lifetime up to 1 s, and there is no influence of the number of ions on the measured charge-state distribution of bovine serum albumin (66.5 kDa), indicating that ion-ion interactions do not adversely affect any of these measurements. Over an order of magnitude gain in measurement speed over single ion analysis is demonstrated, and significant additional gains are expected with this multi-ion measurement method.
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How can native mass spectrometry contribute to characterization of biomacromolecular higher-order structure and interactions? Methods 2018; 144:3-13. [PMID: 29704661 DOI: 10.1016/j.ymeth.2018.04.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/03/2018] [Accepted: 04/21/2018] [Indexed: 01/16/2023] Open
Abstract
Native mass spectrometry (MS) is an emerging approach for characterizing biomacromolecular structure and interactions under physiologically relevant conditions. In native MS measurement, intact macromolecules or macromolecular complexes are directly ionized from a non-denaturing solvent, and key noncovalent interactions that hold the complexes together can be preserved for MS analysis in the gas phase. This technique provides unique multi-level structural information such as conformational changes, stoichiometry, topology and dynamics, complementing conventional biophysical techniques. Despite the maturation of native MS and greatly expanded range of applications in recent decades, further dissemination is needed to make the community aware of such a technique. In this review, we attempt to provide an overview of the current body of knowledge regarding major aspects of native MS and explain how such technique contributes to the characterization of biomacromolecular higher-order structure and interactions.
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Keifer DZ, Jarrold MF. Single-molecule mass spectrometry. MASS SPECTROMETRY REVIEWS 2017; 36:715-733. [PMID: 26873676 DOI: 10.1002/mas.21495] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/15/2016] [Indexed: 06/05/2023]
Abstract
In single-molecule mass spectrometry, the mass of each ion is measured individually; making it suitable for the analysis of very large, heterogeneous objects that cannot be analyzed by conventional means. A range of single-molecule mass spectrometry techniques has been developed, including time-of-flight with cryogenic detectors, a quadrupole ion trap with optical detection, single-molecule Fourier transform ion cyclotron resonance, charge detection mass spectrometry, quadrupole ion traps coupled to charge detector plates, and nanomechanical oscillators. In addition to providing information on mass and heterogeneity, these techniques have been used to study impact craters from cosmic dust, monitor the assembly of viruses, elucidate the fluorescence dynamics of quantum dots, and much more. This review focuses on the merits of each of these technologies, their limitations, and their applications. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:715-733, 2017.
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Affiliation(s)
- David Z Keifer
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN, 47401
| | - Martin F Jarrold
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN, 47401
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8
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Keifer DZ, Alexander AW, Jarrold MF. Spontaneous Mass and Charge Losses from Single Multi-Megadalton Ions Studied by Charge Detection Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:498-506. [PMID: 28083758 DOI: 10.1007/s13361-016-1582-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 12/14/2016] [Accepted: 12/16/2016] [Indexed: 06/06/2023]
Abstract
Spontaneous mass and charge losses from individual multi-megadalton ions have been observed with charge detection mass spectrometry (CDMS) by trapping single hepatitis B virus (HBV) capsids for 3 s. Gradual increases in the oscillation frequency of single ions in the ion trap are attributed mainly to mass loss (probably solvent, water, and/or salt). The total mass lost during the 3 s trapping period peaks at around 20 kDa for 4 MDa HBV T = 4 capsids. Discrete frequency drops punctuate the gradual increases in the oscillation frequencies. The drops are attributed to a sudden loss of charge. In most cases a single positive charge is lost along with some mass (on average around 1000 Da). Charge loss occurs for over 40% of the trapped ions. It usually occurs near the beginning of the trapping event, and it occurs preferentially in regions of the trap with strong electric fields, indicating that external electric fields promote charge loss. This process may contribute to the decrease in m/z resolution that often occurs with megadalton ions. Graphical Abstract ᅟ.
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Affiliation(s)
- David Z Keifer
- Chemistry Department, Indiana University, 800 E Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Andrew W Alexander
- Chemistry Department, Indiana University, 800 E Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Martin F Jarrold
- Chemistry Department, Indiana University, 800 E Kirkwood Ave., Bloomington, IN, 47405, USA.
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9
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Elliott AG, Merenbloom SI, Chakrabarty S, Williams ER. Single Particle Analyzer of Mass: A Charge Detection Mass Spectrometer with a Multi-Detector Electrostatic Ion Trap. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2017; 414:45-55. [PMID: 29129967 PMCID: PMC5676562 DOI: 10.1016/j.ijms.2017.01.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
A new charge detection mass spectrometer that combines array detection and electrostatic ion trapping to repeatedly measure the masses of single ions is described. This instrument has four detector tubes inside an electrostatic ion trap with conical electrodes (cone trap) to provide multiple measurements of an ion on each pass through the trap resulting in a signal gain over a conventional trap with a single detection tube. Simulations of a cone trap and a dual ion mirror trap design indicate that more passes through the trap per unit time are possible with the latter. However, the cone trap has the advantages that ions entering up to 2 mm off the central axis of the trap are still trapped, the trapping time is less sensitive to the background pressure, and only a narrow range of energies are trapped so it can be used for energy selection. The capability of this instrument to obtain information about the molecular weight distributions of heterogeneous high molecular weight samples is demonstrated with 8 MDa polyethylene glycol (PEG) and 50 and 100 nm amine modified polystyrene nanoparticle samples. The measured mass distribution of the PEG sample is centered at 8 MDa. The size distribution obtained from mass measurements of the 100 nm nanoparticle sample is similar to the size distribution obtained from transmission electron microscopy (TEM) images, but most of the smaller nanoparticles observed in TEM images of the 50 nm nanoparticles do not reach a sufficiently high charge to trigger the trap on a single pass and be detected by the mass spectrometer. With the maximum trapping time set to 100 ms, the charge uncertainty is as low as ±2 charges and the mass uncertainty is approximately 2% for PEG and polystyrene ions.
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Affiliation(s)
- Andrew G. Elliott
- Department of Chemistry, University of California, Berkeley, California, 94720-1460
| | - Samuel I. Merenbloom
- Department of Chemistry, University of California, Berkeley, California, 94720-1460
| | - Satrajit Chakrabarty
- Department of Chemistry, University of California, Berkeley, California, 94720-1460
| | - Evan R. Williams
- Department of Chemistry, University of California, Berkeley, California, 94720-1460
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10
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Keifer DZ, Shinholt DL, Jarrold MF. Charge Detection Mass Spectrometry with Almost Perfect Charge Accuracy. Anal Chem 2015; 87:10330-7. [DOI: 10.1021/acs.analchem.5b02324] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- David Z. Keifer
- Chemistry Department, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47401, United States
| | - Deven L. Shinholt
- Chemistry Department, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47401, United States
| | - Martin F. Jarrold
- Chemistry Department, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47401, United States
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11
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Snijder J, Heck AJR. Analytical approaches for size and mass analysis of large protein assemblies. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2014; 7:43-64. [PMID: 25014341 DOI: 10.1146/annurev-anchem-071213-020015] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Analysis of the size and mass of nanoparticles, whether they are natural biomacromolecular or synthetic supramolecular assemblies, is an important step in the characterization of such molecular species. In recent years, electrospray ionization (ESI) has emerged as a technology through which particles with masses up to 100 MDa can be ionized and transferred into the gas phase, preparing them for accurate mass analysis. Here we review currently used methodologies, with a clear focus on native mass spectrometry (MS). Additional complementary methodologies are also covered, including ion-mobility analysis, nanomechanical mass sensors, and charge-detection MS. The literature discussed clearly demonstrates the great potential of ESI-based methodologies for the size and mass analysis of nanoparticles, including very large naturally occurring protein assemblies. The analytical approaches discussed are powerful tools in not only structural biology, but also nanotechnology.
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Affiliation(s)
- Joost Snijder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CH Utrecht, the Netherlands; ,
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12
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Bruce JE, Anderson GA, Udseth HR, Smith RD. Large Molecule Characterization Based upon Individual Ion Detection with Electrospray Ionization-FTICR Mass Spectrometry. Anal Chem 2012; 70:519-25. [PMID: 21644751 DOI: 10.1021/ac9711706] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a new method for mass spectrometric measurements of high-molecular-weight species based on the summation of sequential Fourier transform ion cyclotron resonance (FTICR) spectra of individual multiply charged ions. This approach produces statistically useful mass spectra for large multiply charged molecular species formed by electrospray ionization and circumvents conventional limitations upon achievable resolving power and precision for high-molecular-weight species which arise due to Coulombic constraints. For very large molecules with tens to thousands of charges each, the total number of charges required to define the charge-state distribution, and thus provide accurate mass information, greatly exceeds the useful charge capacity of the FTICR cell. As trapped ion populations approach or exceed this capacity, FTICR performance degrades due to large frequency shifts, peak coalescence phenomena, and rapid loss of ion packet coherence, which effectively precludes high-resolution and precision measurements for molecules above ∼80-kDa size for a 7-T magnetic field strength. The present approach is based on the summation of many spectra having moderate populations of individual ions and relies on sensitivity sufficient for individual ion detection. While the number of trapped ions contributing to each mass spectrum may generally be insufficient to define the isotopic or charge-state distributions (and thus produce accurate information on the molecular weight distribution in a conventional fashion), the present data processing and summation approach suppresses the noise component (as well as smaller signals) that would otherwise be problematic. Importantly, this approach circumvents natural limitations for very high molecular weight species due to Coulombic interactions and thus provides a basis for much greater resolution and mass measurement accuracy than otherwise possible. This paper presents the details of this approach and its demonstration for the 66-kDa protein bovine serum albumin (where the conventional approach is also feasible) and discusses important aspects of the data manipulation.
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Affiliation(s)
- J E Bruce
- Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352
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Rezek B, Krátká M, Kromka A, Kalbacova M. Effects of protein inter-layers on cell–diamond FET characteristics. Biosens Bioelectron 2010; 26:1307-12. [DOI: 10.1016/j.bios.2010.07.027] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 07/08/2010] [Accepted: 07/09/2010] [Indexed: 11/28/2022]
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Makarov A, Denisov E. Dynamics of ions of intact proteins in the Orbitrap mass analyzer. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:1486-1495. [PMID: 19427230 DOI: 10.1016/j.jasms.2009.03.024] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2009] [Revised: 03/26/2009] [Accepted: 03/26/2009] [Indexed: 05/27/2023]
Abstract
While allowing analysis of intact proteins without a theoretical upper mass limit, the Orbitrap mass analyzer demonstrates reduced resolving power as ion mass increases even at a constant mass-to-charge ratio. It is shown that this effect comes from the effects of ion scattering on background gas molecules. The main mechanisms causing decay of acquired transient appear to be fragmentation as well as accelerated dephasing of ion packets. Isotopic resolution of proteins including bovine serum albumin (MW 66.4 kDa) and transferrin (MW 78 kDa) has also been demonstrated. As a part of this study, detection of individual multiply-charged ions of myoglobin (MW 16.9 kDa) has been demonstrated. Quantized distribution of signal intensities for +20 myoglobin ions well above the noise threshold was observed, with high mass accuracy and resolution of recorded individual ions used as an independent confirmation of correct assignment of signal to ions rather than to noise. The latter also allowed us to benchmark the sensitivity of image-current detection and explore in detail factors responsible for signal decay.
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15
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Chang HC. Ultrahigh-mass mass spectrometry of single biomolecules and bioparticles. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2009; 2:169-185. [PMID: 20636058 DOI: 10.1146/annurev-anchem-060908-155245] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Since the advent of soft ionization methods, mass spectrometry (MS) has found widespread application in the life sciences. Mass is now known to be a critical parameter for characterization of biomolecules and their complexes; it is also a useful parameter to characterize bioparticles such as viruses and cells. However, because of the genetic diversity of these entities, it is necessary to measure their masses individually and to obtain the corresponding mean masses and mass distributions. Here, I review recent technological developments that enable mass measurement of ultrahigh-mass biomolecules and bioparticles at the single-ion level. Some representative examples include cryodetection time-of-flight MS of single-megadalton protein ions, Millikan-type mass measurements of single viruses in a cylindrical ion trap, and charge-detection quadrupole ion trap MS of single whole cells. I also discuss the promises and challenges of these new technologies in real-world applications.
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Affiliation(s)
- Huan-Cheng Chang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
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16
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Zhao C, Wood TD, Bruckenstein S. Shifts in protein charge state distributions with varying redox reagents in nanoelectrospray triple quadrupole mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2005; 16:409-416. [PMID: 15734335 DOI: 10.1016/j.jasms.2004.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Revised: 12/02/2004] [Accepted: 12/03/2004] [Indexed: 05/24/2023]
Abstract
The influence of a number of redox reagents on the charge state distribution in nanoelectrospray mass spectrometry was examined using cytochrome c and ubiquitin. The redox active species investigated were: 1,4-benzoquinone, quinhydrone, tetracyanoquinodimethane (TCNQ), hydroquinone, and ascorbic acid. The redox active species was mixed with the protein sample before injection into the nanoelectrospray emitter, and mass spectra were acquired using a triple quadrupole mass spectrometer. Under the same experimental conditions, the charge state distribution of cytochrome c was observed to shift from a weighted average charge state of 14.25 (in the absence of redox species) to 7.10 in the presence of 1,4-benzoquinone. When quinhydrone was mixed with cytochrome c, the charge state distribution of the protein also shifted to lower charge states (weighted average charge state = 9.43), indicative of less charge state reduction for quinhydrone than with 1,4-benzoquinone. Addition of the redox reagent had little effect on the conformation of cytochrome c, as indicated by far ultraviolet circular dichroism spectra. In contrast, the reagents TCNQ, hydroquinone, and ascorbic acid exhibited negligible effects on the observed charge state distribution of the protein. The differing results for these redox reagents can be rationalized in terms of the redox half reactions involving these species. The results observed with ubiquitin upon adding quinhydrone were analogous to those observed with cytochrome c.
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Affiliation(s)
- Cheng Zhao
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, USA
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17
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Peng WP, Cai Y, Chang HC. Optical detection methods for mass spectrometry of macroions. MASS SPECTROMETRY REVIEWS 2004; 23:443-465. [PMID: 15290710 DOI: 10.1002/mas.20002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Detection of macroions has been a challenge in the field of mass spectrometry. Conventional ionization-based detectors, relying on production and multiplication of secondary electrons, are restricted to detection for charged particles of m/z < 1 x 10(6). While both energy-sensitive and charge-sensitive detectors have been developed recently to overcome the limitation, they are not yet in common use. Photon-sensitive detectors are suggested to be an alternative, with which detection of macroions (or charged particles) by either elastic light scattering (ELS) or laser-induced fluorescence (LIF) has been possible. In this article, we provide a critical review on the developments of novel optical detection methods for mass spectrometry of macroions, including both micron-sized and nano-sized synthetic polymers as well as high-mass biomolecules. Design and development of new spectrometers making possible observations of the mass spectra of macroions with sizes in the range of 10-10(3) nm or masses in the range of 1-10(6) MDa are illustrated. The potential and promise of this optical approach toward macroion detection with high efficiency are discussed in practical aspects.
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Affiliation(s)
- Wen-Ping Peng
- Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106
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18
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Bruce JE, Anderson GA, Lin CY, Gorshkov M, Rockwood AL, Smith RD. A novel high-performance fourier transform ion cyclotron resonance cell for improved biopolymer characterization. JOURNAL OF MASS SPECTROMETRY : JMS 2000; 35:85-94. [PMID: 10633238 DOI: 10.1002/(sici)1096-9888(200001)35:1<85::aid-jms910>3.0.co;2-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A new trapped ion cell design for use with Fourier transform ion cyclotron resonance mass spectrometry is described. The design employs 15 cylindrical ring electrodes to generate trapping potential wells and 32 separately assignable rod electrodes for excitation and detection. The rod electrodes are positioned internal to the ring electrodes and provide excitation fields that are thereby linearized along the magnetic field over the entire trapped ion volume. The new design also affords flexibility in the shaping of the trapping field using the 15 ring electrodes. Many different trapping well shapes can be generated by applying different voltages to the individual ring electrodes, ranging from quadratic to linearly ramped along the magnetic field axis, to a shape that is nearly flat over the entire trap volume, but rises very steeply near the ends of the trap. This feature should be useful for trapping larger ion populations and extension of the useful range of ion manipulation and dissociation experiments since the number of stages of ion manipulation or dissociation is limited in practice by the initial trapped ion population size. Predicted trapping well shapes for two different ring electrode configurations are presented, and these and several other possible configurations are discussed, as are the predicted excitation fields based on the use of rod electrodes internal to the trapping ring electrodes. Initial results are presented from an implementation of the design using a 3.5 T superconducting magnet. It was found that ions can be successfully trapped and detected with this cell design and that selected ion accumulation can be performed with the utilization of four rods for quadrupolar excitation. The initial results presented here illustrate the feasibility of this cell design and demonstrate differences in observed performance based upon different trapping well shapes.
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Affiliation(s)
- J E Bruce
- Macromolecular Structures and Dynamics Group, Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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Satterfield M, Brodbelt JS. Sites of reaction of pilocarpine. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1999; 10:209-216. [PMID: 10069045 DOI: 10.1016/s1044-0305(98)00141-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Analysis of the sites of reaction of a biologically important compound, pilocarpine, a molecule with imidazole and butyrolactone rings connected by a methylene bridge, has been accomplished in a quadrupole ion trap with the aim of characterizing its structure/reactivity relationships. Ion-molecule reactions of pilocarpine with chemical ionizing agents, dimethyl ether (DME), 2-methoxyethanol, and trimethyl borate (TMB), along with collision-activated dissociation elucidated the reaction sites of pilocarpine and made possible the comparison of structural features that affect sites of reaction. Based on MS/MS experiments, methylation occurs on the imidazole ring upon reactions with CH3OCH2+ or (CH3OCH2CH2OH)H+ ions but methylation occurs on the lactone ring for reactions with (CH3O)2B+ ions. Bracketing experiments with two model compounds, alpha-methyl-gamma-butyrolactone and N-methyl imidazole, show the imidazole ring to have a greater gas-phase basicity and methyl cation affinity than the lactone ring. The contrast of methylation by TMB ions on the lactone ring is explained by initial addition of the dimethoxyborinium ion, (CH3O)2B+, on the imidazole ring with subsequent collisional activation promoting an intramolecular transfer of a methyl group to the lactone ring with concurrent loss of CH3OBO. Semiempirical molecular orbital calculations are undertaken to further address the favored reaction sites.
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Affiliation(s)
- M Satterfield
- Department of Chemistry and Biochemistry, University of Texas at Austin 78712, USA
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20
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Niessen WM. Advances in instrumentation in liquid chromatography-mass spectrometry and related liquid-introduction techniques. J Chromatogr A 1998; 794:407-35. [PMID: 9491565 DOI: 10.1016/s0021-9673(97)01112-6] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In the past few years, the instrumental developments in the field of combined liquid chromatography-mass spectrometry (LC-MS) and related liquid-introduction techniques has been extremely fast. Soon after the demonstration of the ability to obtain multiply-charged ions from proteins by electrospray ionization, a major impetus was given to the field. Numerous LC-MS systems based on atmospheric-pressure ionization sources have now been described. This paper reviews these instrumental developments with reference to currently available commercial LC-MS systems. Not only low and high flow-rate electrospray on quadrupole instrument is discussed, but also electrospray on ion-trap, double-focusing sector, time-of-flight, and Fourier-transform ion-cyclotron resonance instruments are reviewed.
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Affiliation(s)
- W M Niessen
- Hyphen Mass Spectrometry Consultancy, Leiden, The Netherlands
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Cheng X, Camp DG, Wu Q, Bakhtiar R, Springer DL, Morris BJ, Bruce JE, Anderson GA, Edmonds CG, Smith RD. Molecular weight determination of plasmid DNA using electrospray ionization mass spectrometry. Nucleic Acids Res 1996; 24:2183-9. [PMID: 8668552 PMCID: PMC145889 DOI: 10.1093/nar/24.11.2183] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Ionization and molecular weight (MW) determination of megadalton size plasmid DNA has been achieved using electrospray ionization (ESI) with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. DNA molecules were shown to remain intact through electrospray ionization by collection on a specially prepared surface, followed by agarose gel electrophoresis. Individual highly charged ions of plasmid DNA produced by ESI were trapped in an FTICR cell for up to several hours and reacted with acetic acid to induce charge state shifts. Measurements of mass-to-charge ratios for these multiple peaks arising from charge state shifting give MW measurements of individual ions with an average accuracy of 0.2%. The MW distribution was obtained by measurements for a number of individual ions from the same sample [plasmid DNA: pGEM-5S MW(cal) = 1.946 MDa], yielding a MW(obs) of 1.95 +/- 0.07 MDa for ions clustered in the vicinity of the expected MW.
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Affiliation(s)
- X Cheng
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352, USA
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Guan S, Marshall AG. Ion traps for Fourier transform ion cyclotron resonance mass spectrometry: principles and design of geometric and electric configurations. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/0168-1176(95)04190-v] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Guan S, Paša-Tolić L, Marshall AG, Xiang X. Off-axis injection into an ICR ion trap: a means for efficient capture of a continuous beam of externally generated ions. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0168-1176(94)90014-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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