1
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Han Z, Zheng H, Wu S, Liu L, Chen LC. Effects of anions on the electrospray ionization of proteins in strong acids. Analyst 2024. [PMID: 39176457 DOI: 10.1039/d4an00421c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
The effect of anions on the positive electrospray ionization (ESI) of proteins in different strong acids with varying pH values from 3 to 1 is studied using high-pressure ESI. Reducing the pH from ∼2 to 1 caused a drastic shift in charge state from a high-charge-state distribution (HCSD) to a narrow low-charge-state distribution (LCSD). The shift in charge state was consistent with the circular dichroism result that showed a conformational change due to the "acid-induced folding" of proteins from an unfolding state to a compact molten globule state. Acids of different anions produced noticeable differences in the average charge for HCSD and LCSD. For HCSD, the average charge was lower than the value typically observed using formic and acetic acids. As for LCSD, the average charge was lower than the "native" charge. The high abundance of acid anion that induces the protein compaction was believed to play a role in charge reduction. The effectiveness of anions to "refold" a highly unfolded protein to a compact state and the propensity to reduce the charge of HCSD for proteins appeared to follow the selectivity series of anions towards the stationary phase in ion chromatography. However, the propensity of anions to reduce the charge for LCSD follows quite an opposite trend. The presence of ammonium salt in the acidic solution was found to increase the charge of LCSD. The simple mass spectrum with a narrow distribution of charge state obtained with perchloric acid at pH 1 was demonstrated to facilitate the counting of basic sites.
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Affiliation(s)
- Zhongbao Han
- College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, China.
| | - Huizi Zheng
- College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, China.
| | - Shuyao Wu
- College of Chemistry, Liaoning University, Shenyang, 110036, China
| | - Liyan Liu
- College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang 110034, China.
| | - Lee Chuin Chen
- Faculty of Engineering, University of Yamanashi, 4-3-11, Takeda, Kofu, Yamanashi, 400-8511 Japan.
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2
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Matsuda T, Chen LC. Direct ESI-MS of Ionic Liquids Using High-Pressure Electrospray From Large-Bore Emitters Made of Micropipette Tips. Mass Spectrom (Tokyo) 2024; 13:A0148. [PMID: 39026546 PMCID: PMC11254654 DOI: 10.5702/massspectrometry.a0148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Accepted: 06/30/2024] [Indexed: 07/20/2024] Open
Abstract
Electrospray ionization mass spectrometry of neat undiluted ionic liquid (IL) and the analysis of protein with the doping of IL were performed using high-pressure electrospray. The use of disposable micropipette tips as emitters eased the handling of viscous and easy-to-clog samples and improved the reproducibility of the measurement. A high-pressure operation enabled the stable electrospray of the highly conductive IL from these relatively large bore emitters. The measurement of the current-voltage relationship of 1-ethyl-3-methylimidazolium tetrafluoroborate (Emim BF4) revealed an unusual negative differential resistance that has not been seen in the typical atmospheric or high-pressure electrospray. Mass spectrometric analysis of this IL also showed the characteristic response of various ion species with the emitter voltage. When added to the commonly used protein solution, the mass spectrum also showed protein peaks that correspond to the adduction of fluoroboric acid molecules (HBF4).
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Affiliation(s)
- Takeshi Matsuda
- Faculty of Engineering, University of Yamanashi, Yamanashi, Japan
| | - Lee Chuin Chen
- Faculty of Engineering, University of Yamanashi, Yamanashi, Japan
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3
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Zangl R, Soravia S, Saft M, Löffler JG, Schulte J, Rosner CJ, Bredenbeck J, Essen LO, Morgner N. Time-Resolved Ion Mobility Mass Spectrometry to Solve Conformational Changes in a Cryptochrome. J Am Chem Soc 2024; 146:14468-14478. [PMID: 38757172 DOI: 10.1021/jacs.3c13818] [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: 05/18/2024]
Abstract
Many biological mechanisms rely on the precise control of conformational changes in proteins. Understanding such dynamic processes requires methods for determining structures and their temporal evolution. In this study, we introduce a novel approach to time-resolved ion mobility mass spectrometry. We validated the method on a simple photoreceptor model and applied it to a more complex system, the animal-like cryptochrome from Chlamydomonas reinhardtii (CraCRY), to determine the role of specific amino acids affecting the conformational dynamics as reaction to blue light activation. In our setup, using a high-power LED mounted in the source region of an ion mobility mass spectrometer, we allow a time-resolved evaluation of mass and ion mobility spectra. Cryptochromes like CraCRY are a widespread type of blue light photoreceptors and mediate various light-triggered biological functions upon excitation of their inbuilt flavin chromophore. Another hallmark of cryptochromes is their flexible carboxy-terminal extension (CTE), whose structure and function as well as the details of its interaction with the photolyase homology region are not yet fully understood and differ among different cryptochromes types. Here, we addressed the highly conserved C-terminal domain of CraCRY, to study the effects of single mutations on the structural transition of the C-terminal helix α22 and the attached CTE upon lit-state formation. We show that D321, the putative proton acceptor of the terminal proton-coupled electron transfer event from Y373, is essential for triggering the large-scale conformational changes of helix α22 and the CTE in the lit state, while D323 influences the timing.
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Affiliation(s)
- Rene Zangl
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Sejla Soravia
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Martin Saft
- Department of Chemistry, Philipps University Marburg Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Jan Gerrit Löffler
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main, Germany
| | - Jonathan Schulte
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Christian Joshua Rosner
- Department of Chemistry, Philipps University Marburg Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Jens Bredenbeck
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main, Germany
| | - Lars-Oliver Essen
- Department of Chemistry, Philipps University Marburg Hans-Meerwein-Str. 4, 35032 Marburg, Germany
| | - Nina Morgner
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
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4
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Wesdemiotis C, Williams-Pavlantos KN, Keating AR, McGee AS, Bochenek C. Mass spectrometry of polymers: A tutorial review. MASS SPECTROMETRY REVIEWS 2024; 43:427-476. [PMID: 37070280 DOI: 10.1002/mas.21844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 03/03/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
Ever since the inception of synthetic polymeric materials in the late 19th century, the number of studies on polymers as well as the complexity of their structures have only increased. The development and commercialization of new polymers with properties fine-tuned for specific technological, environmental, consumer, or biomedical applications requires powerful analytical techniques that permit the in-depth characterization of these materials. One such method with the ability to provide chemical composition and structure information with high sensitivity, selectivity, specificity, and speed is mass spectrometry (MS). This tutorial review presents and exemplifies the various MS techniques available for the elucidation of specific structural features in a synthetic polymer, including compositional complexity, primary structure, architecture, topology, and surface properties. Key to every MS analysis is sample conversion to gas-phase ions. This review describes the fundamentals of the most suitable ionization methods for synthetic materials and provides relevant sample preparation protocols. Most importantly, structural characterizations via one-step as well as hyphenated or multidimensional approaches are introduced and demonstrated with specific applications, including surface sensitive and imaging techniques. The aim of this tutorial review is to illustrate the capabilities of MS for the characterization of large, complex polymers and emphasize its potential as a powerful compositional and structural elucidation tool in polymer chemistry.
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Affiliation(s)
| | | | - Addie R Keating
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Andrew S McGee
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Calum Bochenek
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
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5
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Li HI, Prabhu GRD, Buchowiecki K, Urban PL. High-Speed Schlieren Imaging of Vapor Formation in Electrospray Plume. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:244-254. [PMID: 38227955 DOI: 10.1021/jasms.3c00345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Previous mechanistic descriptions of electrosprays mostly focused on the dynamics of Taylor cones, initial droplets, and progeny droplets. However, vapor formation during droplet desolvation in an electrospray plume has not been discussed to a great extent. Here, we implement a double-pass on-axis schlieren high-speed imaging system to observe generation and propagation of vapors in an offline electrospray source under different conditions. Switching between turbulent and laminar vapor flow was observed for all of the scanned conditions, which may be attributed to randomly occurring disturbances in the sample flow inside the electrospray emitter. Calculation of mean vapor flow velocity and analysis of vapor flow patterns were performed using in-house developed image processing programs. Experiments performed at different electrospray voltages (0-6 kV), solvent flow rates (100-600 μL min-1), and methanol concentrations (50-100%), indicate only a weak dependency between electrospray voltage and mean vapor velocity, implying that the vapor is mostly neutral; thus, the vapor is not accelerated by electric field. On the other hand, electrospraying solutions of analytes (with mass 151 Da or 12 kDa) did not remarkably increase the overall vapor flow velocity. The source of vapor's velocity is attributed to the inertia of the electrospray droplets. Although there are some differences between a modern electrospray ionization (ESI) setup and the setup used in our experiment (e.g., using a higher flow rate and larger emitter), we believe the findings of our study can be projected to a modern ESI setup.
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Affiliation(s)
- Hou-I Li
- Department of Chemistry, National Tsing Hua University, 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Gurpur Rakesh D Prabhu
- Department of Chemistry, National Tsing Hua University, 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Krzysztof Buchowiecki
- Department of Chemistry, National Tsing Hua University, 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Pawel L Urban
- Department of Chemistry, National Tsing Hua University, 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
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6
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Pounot K, Piersson C, Goring AK, Rosu F, Gabelica V, Weik M, Han S, Fichou Y. Mutations in Tau Protein Promote Aggregation by Favoring Extended Conformations. JACS AU 2024; 4:92-100. [PMID: 38274251 PMCID: PMC10806773 DOI: 10.1021/jacsau.3c00550] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/17/2023] [Accepted: 10/17/2023] [Indexed: 01/27/2024]
Abstract
Amyloid aggregation of the intrinsically disordered protein (IDP) tau is involved in several diseases, called tauopathies. Some tauopathies can be inherited due to mutations in the gene encoding tau, which might favor the formation of tau amyloid fibrils. This work aims at deciphering the mechanisms through which the disease-associated single-point mutations promote amyloid formation. We combined biochemical and biophysical characterization, notably, small-angle X-ray scattering (SAXS), to study six different FTDP-17 derived mutations. We found that the mutations promote aggregation to different degrees and can modulate tau conformational ensembles, intermolecular interactions, and liquid-liquid phase separation propensity. In particular, we found a good correlation between the aggregation lag time of the mutants and their radii of gyration. We show that mutations disfavor intramolecular protein interactions, which in turn favor extended conformations and promote amyloid aggregation. This work proposes a new connection between the structural features of tau monomers and their propensity to aggregate, providing a novel assay to evaluate the aggregation propensity of IDPs.
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Affiliation(s)
- Kevin Pounot
- Univ.
Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Clara Piersson
- Univ.
Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, IECB, 33600 Pessac, France
| | - Andrew K. Goring
- Department
of Chemistry and Biochemistry, University
of California Los Angeles, Los Angeles, California 90095, United States
| | - Frédéric Rosu
- Univ.
Bordeaux, CNRS, INSERM, IECB, UAR3033, US01, F-33600 Pessac, France
| | - Valérie Gabelica
- Univ.
Bordeaux, CNRS, INSERM, IECB, UAR3033, US01, F-33600 Pessac, France
- Univ.
Bordeaux, CNRS, INSERM, ARNA, UMR5320, U1212, IECB, 33600 Pessac, France
| | - Martin Weik
- Univ.
Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Songi Han
- Department
of Chemical Engineering, University of California
Santa Barbara, Santa Barbara, California 93106, United States
- Department
of Chemistry and Biochemistry, University
of California Santa Barbara, Santa
Barbara, California 93106, United States
| | - Yann Fichou
- Univ.
Bordeaux, CNRS, Bordeaux INP, CBMN, UMR 5248, IECB, 33600 Pessac, France
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7
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Hsu CY, Prabhu GRD, Chang CH, Hsu PC, Buchowiecki K, Urban PL. Are Most Micrometer Droplets (>10 μm) Wasted in Electrospray Ionization? An Insight from Real-Time High-Speed Imaging. Anal Chem 2023; 95:14702-14709. [PMID: 37725015 DOI: 10.1021/acs.analchem.3c02799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
Electrospray ionization (ESI) is one of the main techniques used in mass spectrometry (MS) of nonvolatile compounds. ESI is a disordered process, in which a large number of polydisperse droplets are projected from a fluctuating Taylor cone and jet protruding ESI emitter. Here, we disclose a system for sectioning electrospray plumes to discrete packets with millisecond and submillisecond lifetime, which are introduced to the MS orifice, one at a time. A high-speed camera was triggered at 10,000 frames per second to capture consecutive images of the electrospray packets transmitted to the mass spectrometer. We further correlated the high-speed images of electrospray packets with MS signals of a test analyte (acetaminophen). Following computational treatment of the images, we determined the number of droplet observations (<300), average diameter of droplets (∼10-20 μm), and average volume of droplets (few tens of picoliters) in the individual electrospray packets. The result shows that most micrometer droplets (>10 μm) do not have any significant contribution to the MS signals. This finding is in agreement with the prior conjecture that most of the MS signals are mainly attributed to nanodroplets. Based on this finding, one can deduce that only a small number of the initial microdroplets effectively carry analyte molecules that undergo ionization. We discuss that, in future, one may propose a way to "recharge" the emitted initial micrometer droplets to increase the efficiency of conventional ESI setups.
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Affiliation(s)
- Chun-Yao Hsu
- Department of Chemistry, National Tsing Hua University 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Gurpur Rakesh D Prabhu
- Department of Chemistry, National Tsing Hua University 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Ching-Han Chang
- Department of Chemistry, National Tsing Hua University 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Pin-Chieh Hsu
- Department of Chemistry, National Tsing Hua University 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Krzysztof Buchowiecki
- Department of Chemistry, National Tsing Hua University 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
| | - Pawel L Urban
- Department of Chemistry, National Tsing Hua University 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, 101, Section 2, Kuang-Fu Rd., Hsinchu 300044, Taiwan
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8
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Luan M, Hou Z, Zhang B, Ma L, Yuan S, Liu Y, Huang G. Inter-Domain Repulsion of Dumbbell-Shaped Calmodulin during Electrospray Ionization Revealed by Molecular Dynamics Simulations. Anal Chem 2023; 95:8798-8806. [PMID: 37309130 DOI: 10.1021/acs.analchem.2c05630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The mechanisms whereby protein ions are released from nanodroplets at the liquid-gas interface have continued to be controversial since electrospray ionization (ESI) mass spectrometry was widely applied in biomolecular structure analysis in solution. Several viable pathways have been proposed and verified for single-domain proteins. However, the ESI mechanism of multi-domain proteins with more complicated and flexible structures remains unclear. Herein, dumbbell-shaped calmodulin was chosen as a multi-domain protein model to perform molecular dynamics simulations to investigate the structural evolution during the ESI process. For [Ca4CAM], the protein followed the classical charge residue model. As the inter-domain electrostatic repulsion increased, the droplet was found to split into two sub-droplets, while stronger-repulsive apo-calmodulin unfolded during the early evaporation stage. We designated this novel ESI mechanism as the domain repulsion model, which provides new mechanistic insights into further exploration of proteins containing more domains. Our results suggest that greater attention should be paid to the effect of domain-domain interactions on structure retention during liquid-gas interface transfer when mass spectrometry is used as the developing technique in gas phase structural biology.
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Affiliation(s)
- Moujun Luan
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Zhuanghao Hou
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
| | - Buchun Zhang
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Likun Ma
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Siming Yuan
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
- Department of Pharmacy, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Yangzhong Liu
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
- Department of Pharmacy, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
| | - Guangming Huang
- Department of Cardiology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
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9
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Kwan V, Ballaney P, Consta S. Limitations of Atomistic Molecular Dynamics to Reveal Ejection of Proteins from Charged Nanodroplets. J Phys Chem B 2023. [PMID: 37216215 DOI: 10.1021/acs.jpcb.3c01313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Atomistic molecular dynamics (MD) is frequently used to unravel the mechanisms of macroion release from electrosprayed droplets. However, atomistic MD is currently feasible for only the smallest window of droplet sizes appearing at the end steps of a droplet's lifetime. The relevance of the observations made to the actual droplet evolution, which is much longer than the simulated sizes, has not been addressed yet in the literature. Here, we perform a systematic study of the desolvation mechanisms of poly(ethylene glycol) (PEG), protonated peptides of different compositions, and proteins, to (a) obtain insight into the charging mechanism of macromolecules in larger droplets than those that are currently amenable to atomistic MD and (b) examine whether currently used atomistic MD modeling can establish the extrusion mechanism of proteins from droplets. To mimic larger droplets that are not amenable to MD modeling, we scale down the systems, by simulating a large droplet size relative to the macromolecule. MD of PEG charging reveals that, above a critical droplet size, ions are available near the backbone of the macromolecule, but charging occurs only transiently by transfer of ions from the solvent to the macroion, while below the critical size, the capture of the ion from PEG has a lifetime sufficiently long for the extrusion of a charged PEG from the aqueous droplet. This is the first report of the role of droplet curvature in the relation between macroion conformation and charging. Simulations of protonated peptides with a high degree of hydrophobicity show that partial extrusion of a peptide from the droplet surface is rare relative to desolvation by drying-out. Different from what has been presented in the literature, we argue that atomistic MD simulations have not sufficiently established the extrusion mechanism of proteins from droplets and their charging mechanism. We also argue that release of highly charged proteins can occur at an earlier stage of a droplet's lifetime than predicted by atomistic MD. In this earlier stage, we emphasize the key role of jets emanating from a droplet at the point of charge-induced instability in the release of proteins.
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Affiliation(s)
- Victor Kwan
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Pranav Ballaney
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Styliani Consta
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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10
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Sharif D, Foroushani SH, Attanayake K, Dewasurendra VK, DeBastiani A, DeVor A, Johnson MB, Li P, Valentine SJ. Capillary Vibrating Sharp-Edge Spray Ionization Augments Field-Free Ionization Techniques to Promote Conformer Preservation in the Gas-Phase for Intractable Biomolecular Ions. J Phys Chem B 2022; 126:8970-8984. [PMID: 36318704 PMCID: PMC10278089 DOI: 10.1021/acs.jpcb.2c04960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Field-free capillary vibrating sharp-edge spray ionization (cVSSI) is evaluated for its ability to conduct native mass spectrometry (MS) experiments. The charge state distributions for nine globular proteins are compared using field-free cVSSI, field-enabled cVSSI, and electrospray ionization (ESI). In general, for both positive and negative ion mode, the average charge state (qavg) increases for field-free cVSSI with increasing molecular weight similar to ESI. A clear difference is that the qavg is significantly lower for field-free conditions in both analyses. Two proteins, leptin and thioredoxin, exhibit bimodal charge state distributions (CSDs) upon the application of voltage in positive ion mode; only a monomodal distribution is observed for field-free conditions. In negative ion mode, thioredoxin exhibits a multimodal CSD upon the addition of voltage to cVSSI. Extensive molecular dynamics (MD) simulations of myoglobin and leptin in nanodroplets suggest that the multimodal CSD for leptin may originate from increased conformational "breathing" (decreased packing) and association with the droplet surface. These properties along with increased droplet charge appear to play critical roles in shifting ionization processes for some proteins. Further exploration and development of field-free cVSSI as a new ionization source for native MS especially as applied to more flexible biomolecular species is warranted.
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Affiliation(s)
- Daud Sharif
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
| | - Samira Hajian Foroushani
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
| | - Kushani Attanayake
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
| | - Vikum K Dewasurendra
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia26506, United States
| | - Anthony DeBastiani
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
| | - Amanda DeVor
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
| | - Matthew B Johnson
- Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia26506, United States
| | - Peng Li
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
| | - Stephen J Valentine
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia26506, United States
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11
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Santambrogio C, Ponzini E, Grandori R. Native mass spectrometry for the investigation of protein structural (dis)order. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140828. [PMID: 35926718 DOI: 10.1016/j.bbapap.2022.140828] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 06/24/2022] [Accepted: 07/29/2022] [Indexed: 06/15/2023]
Abstract
A central challenge in structural biology is represented by dynamic and heterogeneous systems, as typically represented by proteins in solution, with the extreme case of intrinsically disordered proteins (IDPs) [1-3]. These proteins lack a specific three-dimensional structure and have poorly organized secondary structure. For these reasons, they escape structural characterization by conventional biophysical methods. The investigation of these systems requires description of conformational ensembles, rather than of unique, defined structures or bundles of largely superimposable structures. Mass spectrometry (MS) has become a central tool in this field, offering a variety of complementary approaches to generate structural information on either folded or disordered proteins [4-6]. Two main categories of methods can be recognized. On one side, conformation-dependent reactions (such as cross-linking, covalent labeling, H/D exchange) are exploited to label molecules in solution, followed by the characterization of the labeling products by denaturing MS [7-11]. On the other side, non-denaturing ("native") MS can be used to directly explore the different conformational components in terms of geometry and structural compactness [12-16]. All these approaches have in common the capability to conjugate protein structure investigation with the peculiar analytical power of MS measurements, offering the possibility of assessing species distributions for folding and binding equilibria and the combination of both. These methods can be combined with characterization of noncovalent complexes [17, 18] and post-translational modifications [19-23]. This review focuses on the application of native MS to protein structure and dynamics investigation, with a general methodological section, followed by examples on specific proteins from our laboratory.
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Affiliation(s)
- Carlo Santambrogio
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
| | - Erika Ponzini
- Materials Science Department, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milan, Italy; COMiB Research Center, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milan, Italy
| | - Rita Grandori
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
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12
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Walker TE, Laganowsky A, Russell DH. Surface Activity of Amines Provides Evidence for the Combined ESI Mechanism of Charge Reduction for Protein Complexes. Anal Chem 2022; 94:10824-10831. [PMID: 35862200 PMCID: PMC9357154 DOI: 10.1021/acs.analchem.2c01814] [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
Charge reduction reactions are important for native mass spectrometry (nMS) because lower charge states help retain native-like conformations and preserve noncovalent interactions of protein complexes. While mechanisms of charge reduction reactions are not well understood, they are generally achieved through the addition of small molecules, such as polyamines, to traditional nMS buffers. Here, we present new evidence that surface-active, charge reducing reagents carry away excess charge from the droplet after being emitted due to Coulombic repulsion, thereby reducing the overall charge of the droplet. Furthermore, these processes are directly linked to two mechanisms for electrospray ionization, specifically the charge residue and ion evaporation models (CRM and IEM). Selected protein complexes were analyzed in solutions containing ammonium acetate and selected trialkylamines or diaminoalkanes of increasing alkyl chain lengths. Results show that amines with higher surface activity have increased propensities for promoting charge reduction of the protein ions. The electrospray ionization (ESI) emitter potential was also found to be a major contributing parameter to the prevalence of charge reduction; higher emitter potentials consistently coincided with lower average charge states among all protein complexes analyzed. These results offer experimental evidence for the mechanism of charge reduction in ESI and also provide insight into the final stages of the ESI and their impact on biological ions.
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Affiliation(s)
- Thomas E Walker
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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13
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Morreel K, t’Kindt R, Debyser G, Jonckheere S, Sandra P. Diving into the Structural Details of In Vitro Transcribed mRNA Using Liquid Chromatography–Mass Spectrometry-Based Oligonucleotide Profiling. LCGC EUROPE 2022. [DOI: 10.56530/lcgc.eu.jk3969w4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The production process of in vitro transcribed messenger RNA (IVT-mRNA)-based vaccines has matured in recent years, partly due to the fight against infectious diseases such as COVID-19. One key to success has been the use of modified, next to canonical, nucleotides and the efficient addition of a Cap-structure and poly A tail to the 5’ and 3’ end, respectively, of this massive biomolecule. These important features affect mRNA stability and impact translation efficiency, consequently boosting the optimization and implementation of liquid chromatography–mass spectrometry (LC–MS)-based oligonucleotide profiling methods for their characterization. This article will provide an overview of these LC–MS methods at a fundamental and application level. It will be shown how LC–MS is implemented in mRNA-based vaccine analysis to determine the capping efficiency and the poly A tail length, and how it allows, via RNA mapping, (i) to determine the mRNA sequence, (ii) to screen the fidelity of the manufactured modifications, and (iii) to identify and quantify unwanted modifications resulting from manufacturing or storage, and sequence variants resulting from mutation or transcription errors.
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14
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Luan M, Hou Z, Huang G. Suppression of Protein Structural Perturbations in Native Electrospray Ionization during the Final Evaporation Stages Revealed by Molecular Dynamics Simulations. J Phys Chem B 2021; 126:144-150. [PMID: 34964355 DOI: 10.1021/acs.jpcb.1c09130] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Native electrospray ionization was known to preserve the protein structure in solution, which overcame the uncontrollable acidification of droplets during transfer from solution into the gas phase in conventional electrospray ionization. However, detailed experimental studies on when and how could native electrospray ionization minimize structural perturbations remain quite unclear. Herein, we conducted molecular dynamics simulations to investigate the protein structure evolution during electrospray ionization. At a neutral droplet pH, the protein structure in solution could be retained after evaporation, which was in accordance with previous reports. As the droplet pH deviated from neutral, we have found that the compact protein structure would not unfold until the last 10 ns prior to the final desolvation, which demonstrated that the role of native electrospray ionization in preserving the protein structure was mainly reflected on the final evaporation stages. The present study might provide new insights into studying the microscopic biomolecular events occurring during the liquid-gas interface transition and their influence on solution-structure retention.
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Affiliation(s)
- Moujun Luan
- The First Affiliated Hospital of USTC, University of Science and Technology of China, 230001 Hefei, China.,School of Chemistry and Materials Science, University of Science and Technology of China, 230026 Hefei, China
| | - Zhuanghao Hou
- The First Affiliated Hospital of USTC, University of Science and Technology of China, 230001 Hefei, China.,School of Chemistry and Materials Science, University of Science and Technology of China, 230026 Hefei, China.,National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029 Hefei, China
| | - Guangming Huang
- The First Affiliated Hospital of USTC, University of Science and Technology of China, 230001 Hefei, China.,School of Chemistry and Materials Science, University of Science and Technology of China, 230026 Hefei, China.,National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029 Hefei, China
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15
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Greisch JF, den Boer MA, Lai SH, Gallagher K, Bondt A, Commandeur J, Heck AJR. Extending Native Top-Down Electron Capture Dissociation to MDa Immunoglobulin Complexes Provides Useful Sequence Tags Covering Their Critical Variable Complementarity-Determining Regions. Anal Chem 2021; 93:16068-16075. [PMID: 34813704 PMCID: PMC8655740 DOI: 10.1021/acs.analchem.1c03740] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
Native top-down mass
spectrometry (MS) is gaining traction for
the analysis and sequencing of intact proteins and protein assemblies,
giving access to their mass and composition, as well as sequence information
useful for identification. Herein, we extend and apply native top-down
MS, using electron capture dissociation, to two submillion Da IgM-
and IgG-based oligomeric immunoglobulins. Despite structural similarities,
these two systems are quite different. The ∼895 kDa noncovalent
IgG hexamer consists of six IgG subunits hexamerizing in solution
due to three specifically engineered mutations in the Fc region, whereas
the ∼935 kDa IgM oligomer results from the covalent assembly
of one joining (J) chain and 5 IgM subunits into an asymmetric “pentamer”
stabilized by interchain disulfide bridges. Notwithstanding their
size, structural differences, and complexity, we observe that their
top-down electron capture dissociation spectra are quite similar and
straightforward to interpret, specifically providing informative sequence
tags covering the highly variable CDR3s and FR4s of the Ig subunits
they contain. Moreover, we show that the electron capture dissociation
fragmentation spectra of immunoglobulin oligomers are essentially
identical to those obtained for their respective monomers. Demonstrated
for recombinantly produced systems, the approach described here opens
up new prospects for the characterization and identification of IgMs
circulating in plasma, which is important since IgMs play a critical
role in the early immune response to pathogens such as viruses and
bacteria.
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Affiliation(s)
- Jean-Francois Greisch
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Maurits A den Boer
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Szu-Hsueh Lai
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Kelly Gallagher
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Albert Bondt
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Jan Commandeur
- MSVision, Televisieweg 40, 1322 AM Almere, The Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
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16
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Abaye DA, Agbo IA, Nielsen BV. Current perspectives on supercharging reagents in electrospray ionization mass spectrometry. RSC Adv 2021; 11:20355-20369. [PMID: 35479879 PMCID: PMC9033978 DOI: 10.1039/d1ra00745a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/02/2021] [Indexed: 11/21/2022] Open
Abstract
In electrospray ionization mass spectrometry (ESI-MS), analytes are introduced into the mass spectrometer in typically aqueous-organic solvent mixtures, including pH modifiers. One mechanism for improving the signal intensity and simultaneously increasing the generation of higher charge-state ions is the inclusion of small amounts (approx. <0.5% v/v mobile phase solution) of charge-inducing or supercharging reagents, such as m-nitrobenzyl alcohol, o-nitrobenzyl alcohol, m-nitrobenzonitrile, m-(trifluoromethyl)-benzyl alcohol and sulfolane. We explore the direct and indirect (colligative properties) that have been proposed as responsible for their modes of action during ESI. Of the many theorized mechanisms of ESI, we re-visit the three most popular and highlight how they are impacted by supercharging observations on small ions to large molecules including proteins. We then provide a comprehensive list of 34 supercharging reagents that have been demonstrated in ESI experiments. We include an additional 19 potential candidate isomers as supercharging reagents and comment on their broad physico-chemical properties. It is becoming increasingly obvious that advances in technology and improved ion source design, analyzers e.g. the use of ion mobility, ion trap, circular dichroism (CD) spectroscopy, together with computer modeling are increasing the knowledge base and, together with the untested isomers and yet-to-be unearthed ones, offer opportunities for further research and application in other areas of polymer research. A simple illustration of the positive electrospray ionization (ESI) environment.![]()
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Affiliation(s)
- Daniel A. Abaye
- Department of Basic Sciences
- School of Basic and Biomedical Sciences
- University of Health and Allied Sciences
- Ho
- Ghana
| | - Irene A. Agbo
- Department of Basic Sciences
- School of Basic and Biomedical Sciences
- University of Health and Allied Sciences
- Ho
- Ghana
| | - Birthe V. Nielsen
- School of Science
- Faculty of Engineering and Science
- University of Greenwich
- Kent
- UK
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17
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Silzel JW, Murphree TA, Paranji RK, Guttman MM, Julian RR. Probing the Stability of Proline Cis/Trans Isomers in the Gas Phase with Ultraviolet Photodissociation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1974-1980. [PMID: 32808771 DOI: 10.1021/jasms.0c00242] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Although most peptide bonds in proteins exist in the trans configuration, when cis peptide bonds do occur, they can have major impact on protein structure and function. The rapid identification of cis peptide bonds is therefore an important task. Peptide bonds containing proline are more likely to adopt the cis configuration because the ring connecting the side chain and backbone in proline flattens the energetic landscape relative to amino acids with free side chains. Examples of cis proline isomers have been identified in both solution and in the gas phase by a variety of structure-probing methods. Mass spectrometry is an attractive potential method for identifying cis proline due to its speed and sensitivity; however, the question remains of whether cis/trans proline isomers originating in solution are preserved during ionization and manipulation within a mass spectrometer. Herein, we investigate the gas-phase stability of isolated solution-phase cis and trans proline isomers using a synthetic peptide sequence with a Tyr-Pro-Pro motif. A variety of dissociation methods were explored to evaluate their potential to distinguish cis/trans configuration, including collision-induced dissociation, radical-directed dissociation, and photodissociation. Only photodissociation employed in conjunction with extremely gentle electrospray and charge solvation by 18-crown-6 ether was able to distinguish cis/trans isomers for our model peptide, suggesting that any thermal activation during transfer or while in the gas phase leads to isomer scrambling. Furthermore, the necessity for 18-crown-6 suggests that intramolecular charge solvation taking place during electrospray ionization can override cis/trans isomer homogeneity. Overall, the results suggest that solution-phase cis/trans proline isomers are fragile and easily lost during electrospray, requiring careful selection of instrument parameters and consideration of charge solvation to prevent cis/trans scrambling.
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Affiliation(s)
- Jacob W Silzel
- Department of Chemistry, University of California, 501 Big Springs Road, Riverside, California 92521, United States
| | - Taylor A Murphree
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Rajan K Paranji
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Miklos M Guttman
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Ryan R Julian
- Department of Chemistry, University of California, 501 Big Springs Road, Riverside, California 92521, United States
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18
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Sutton JM, Guimaraes GJ, Annavarapu V, van Dongen WD, Bartlett MG. Current State of Oligonucleotide Characterization Using Liquid Chromatography-Mass Spectrometry: Insight into Critical Issues. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1775-1782. [PMID: 32812756 DOI: 10.1021/jasms.0c00179] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
As interests increase in oligonucleotide therapeutics, there has been a greater need for analytical techniques to properly analyze and quantitate these biomolecules. This article looks into some of the existing chromatographic approaches for oligonucleotide analysis, including anion exchange, hydrophilic interaction liquid chromatography, and ion pair chromatography. Some of the key advantages and challenges of these chromatographic techniques are discussed. Colloid formation in mobile phases of alkylamines and fluorinated alcohols, a recently discovered analytical challenge, is discussed. Mass spectrometry is the method of choice to directly obtain structural information about oligonucleotide therapeutics. Mass spectrometry sensitivity challenges are reviewed, including comparison to other oligonucleotide techniques, salt adduction, and the multiple charge state envelope. Ionization of oligonucleotides through the charge residue model, ion evaporation model, and chain ejection model are analyzed. Therapeutic oligonucleotides have to undergo approval from major regulatory agencies, and the impurities and degradation products must be well-characterized to be approved. Current accepted thresholds for oligonucleotide impurities are reported. Aspects of the impurities and degradation products from these types of molecules are discussed as well as optimal analytical strategies to determine oligonucleotide related substances. Finally, ideas are proposed on how the field of oligonucleotide therapeutics may improve to aid in future analysis.
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Affiliation(s)
- J Michael Sutton
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 250 W. Green Street, Athens, Georgia 30602-2352, United States
| | - Guilherme J Guimaraes
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 250 W. Green Street, Athens, Georgia 30602-2352, United States
| | - Vidya Annavarapu
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 250 W. Green Street, Athens, Georgia 30602-2352, United States
| | | | - Michael G Bartlett
- Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, 250 W. Green Street, Athens, Georgia 30602-2352, United States
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19
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Yin Z, Huang J, Miao H, Hu O, Li H. High-Pressure Electrospray Ionization Yields Supercharged Protein Complexes from Native Solutions While Preserving Noncovalent Interactions. Anal Chem 2020; 92:12312-12321. [DOI: 10.1021/acs.analchem.0c01965] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Zhibin Yin
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Jing Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Hui Miao
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Ou Hu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Huilin Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006, China
- Guangdong Key Laboratory of Chiral Molecule and Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, Guangdong 510006, China
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20
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Yousef EN, Angel LA. Comparison of the pH-dependent formation of His and Cys heptapeptide complexes of nickel(II), copper(II), and zinc(II) as determined by ion mobility-mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4489. [PMID: 31881105 DOI: 10.1002/jms.4489] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/05/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
The analog methanobactin (amb) peptide with the sequence ac-His1 -Cys2 -Gly3 -Pro4 -Tyr5 -His6 -Cys7 (amb5A ) will bind the metal ions of zinc, nickel, and copper. To further understand how amb5A binds these metals, we have undertaken a series of studies of structurally related heptapeptides where one or two of the potential His or Cys binding sites have been replaced by Gly, or the C-terminus has been blocked by amidation. The studies were designed to compare how these metals bind to these sequences in different pH solutions of pH 4.2 to 10 and utilized native electrospray ionization (ESI) with ion mobility-mass spectrometry (IM-MS) which allows for the quantitative analysis of the charged species produced during the reactions. The native ESI conditions were chosen to conserve as much of the solution-phase behavior of the amb peptides as possible and an analysis of how the IM-MS results compare with the expected solution-phase behavior is discussed. The oligopeptides studied here have applications for tag-based protein purification methods, as therapeutics for diseases caused by elevated metal ion levels or as inhibitors for metal-protein enzymes such as matrix metalloproteinases.
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Affiliation(s)
- Enas N Yousef
- Department of Chemistry, Texas A&M University-Commerce, Commerce, Texas, 75428, USA
| | - Laurence A Angel
- Department of Chemistry, Texas A&M University-Commerce, Commerce, Texas, 75428, USA
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21
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Ultrafast enzymatic digestion of proteins by microdroplet mass spectrometry. Nat Commun 2020; 11:1049. [PMID: 32103000 PMCID: PMC7044307 DOI: 10.1038/s41467-020-14877-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/21/2020] [Indexed: 11/15/2022] Open
Abstract
Enzymatic digestion for protein sequencing usually requires much time, and does not always result in high sequence coverage. Here we report the use of aqueous microdroplets to accelerate enzymatic reactions and, in particular, to improve protein sequencing. When a room temperature aqueous solution containing 10 µM myoglobin and 5 µg mL−1 trypsin is electrosonically sprayed (−3 kV) from a homemade setup to produce tiny (∼9 µm) microdroplets, we obtain 100% sequence coverage in less than 1 ms of digestion time, in sharp contrast to 60% coverage achieved by incubating the same solution at 37 °C for 14 h followed by analysis with a commercial electrospray ionization source that produces larger (∼60 µm) droplets. We also confirm the sequence of the therapeutic antibody trastuzumab (∼148 kDa), with a sequence coverage of 100% for light chains and 85% for heavy chains, demonstrating the practical utility of microdroplets in drug development. Mass spectrometry (MS)-based protein sequencing usually relies on in-solution proteolytic digestion, which is time-consuming and inefficient for certain proteins. Here, the authors achieve full protein sequence coverage in less than 1 ms by subjecting protein-protease mixtures to electrosonic spray ionization-MS.
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22
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Javanshad R, Maser TL, Honarvar E, Venter AR. The Addition of Polar Organic Solvent Vapors During the Analysis of Proteins by DESI-MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:2571-2575. [PMID: 31758521 DOI: 10.1007/s13361-019-02345-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 06/10/2023]
Abstract
Exposure of electrospray droplets to organic vapors was shown to dramatically reduce alkali-metal adduction on protein ions and shift protein charge states. Since DESI-MS is affected by similar adduct species as ESI-MS and shares similar ionization mechanisms, polar organic vapor additives should likewise also improve the DESI-MS analysis of proteins. Here the DESI spray was exposed to a variety of polar organic vapor additives. Head space vapors of polar organic solvents were entrained in nitrogen gas and delivered to the atmosphere inside a semi-enclosed plastic enclosure surrounding the spray plume. The vapors of acetone, acetonitrile, ethyl acetate, methanol, and water were investigated. Vapor dependent effects were observed with respect to changes in protein charge state distributions and signal intensities. With ethyl acetate vapor addition, the signal intensities of all proteins investigated were significantly increased, including proteins larger than 25 kDa such as carbonic anhydrase II and bovine serum albumin.
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Affiliation(s)
- Roshan Javanshad
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, 49008-5413, USA
| | - Tara L Maser
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, 49008-5413, USA
| | - Elahe Honarvar
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, 49008-5413, USA
| | - Andre R Venter
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, 49008-5413, USA.
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23
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Han JY, Choi TS, Heo CE, Son MK, Kim HI. Gas-phase conformations of intrinsically disordered proteins and their complexes with ligands: Kinetically trapped states during transfer from solution to the gas phase. MASS SPECTROMETRY REVIEWS 2019; 38:483-500. [PMID: 31021441 DOI: 10.1002/mas.21596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/10/2019] [Indexed: 06/09/2023]
Abstract
Flexible structures of intrinsically disordered proteins (IDPs) are crucial for versatile functions in living organisms, which involve interaction with diverse partners. Electrospray ionization ion mobility mass spectrometry (ESI-IM-MS) has been widely applied for structural characterization of apo-state and ligand-associated IDPs via two-dimensional separation in the gas phase. Gas-phase IDP structures have been regarded as kinetically trapped states originated from conformational features in solution. However, an implication of the states remains elusive in the structural characterization of IDPs, because it is unclear what structural property of IDPs is preserved. Recent studies have indicated that the conformational features of IDPs in solution are not fully reproduced in the gas phase. Nevertheless, the molecular interactions captured in the gas phase amplify the structural differences between IDP conformers. Therefore, an IDP conformational change that is not observed in solution is observable in the gas-phase structures obtained by ESI-IM-MS. Herein, we have presented up-to-date researches on the key implications of kinetically trapped states in the gas phase with a brief summary of the structural dynamics of IDPs in ESI-IM-MS.
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Affiliation(s)
- Jong Yoon Han
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Tae Su Choi
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093
| | - Chae Eun Heo
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Myung Kook Son
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
| | - Hugh I Kim
- Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea
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24
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Lin YF, Yousef EN, Torres E, Truong L, Zahnow JM, Donald CB, Qin Y, Angel LA. Weak Acid-Base Interactions of Histidine and Cysteine Affect the Charge States, Tertiary Structure, and Zn(II)-Binding of Heptapeptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:2068-2081. [PMID: 31332742 DOI: 10.1007/s13361-019-02275-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 06/10/2019] [Accepted: 06/18/2019] [Indexed: 06/10/2023]
Abstract
Zinc fingers are proteins that are characterized by the coordination of zinc ions by an amino acid sequence that commonly contains two histidines and two cysteines (2His-2Cys motif). Investigations of oligopeptides that contain the 2His-2Cys motif, e.g., acetyl-His1-Cys2-Gly3-Pro4-Tyr5-His6-Cys7, have discovered they exhibit pH-dependent Zn(II) chelation and have redox activities with Cu(I/II), forming a variety of metal complexes. To further understand how these 2His-2Cys oligopeptides bind these metal ions, we have undertaken a series of ion mobility-mass spectrometry and B3LYP/LanL2DZ computational studies of structurally related heptapeptides. Starting with the sequence above, we have modified the potential His, Cys, or C-terminus binding sites and report how these changes in primary structure affect the oligopeptides positive and negative charge states, conformational structure, collision-induced breakdown energies, and how effectively Zn(II) binds to these sequences. The results show evidence that the weak acid-base properties of Cys-His are intrinsically linked and can result in an intramolecular salt-bridged network that affects the oligopeptide properties.
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Affiliation(s)
- Yu-Fu Lin
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA
| | - Enas N Yousef
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA
| | - Efren Torres
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA
| | - Linh Truong
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA
| | - James M Zahnow
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA
| | - Cole B Donald
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA
| | - Ying Qin
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA
| | - Laurence A Angel
- Department of Chemistry, Texas A&M University-Commerce, 2600 S Neal St, Commerce, TX, 75428, USA.
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25
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Greisch JF, Tamara S, Scheltema RA, Maxwell HWR, Fagerlund RD, Fineran PC, Tetter S, Hilvert D, Heck AJR. Expanding the mass range for UVPD-based native top-down mass spectrometry. Chem Sci 2019; 10:7163-7171. [PMID: 31588283 PMCID: PMC6764275 DOI: 10.1039/c9sc01857c] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 06/30/2019] [Indexed: 12/13/2022] Open
Abstract
Native top-down proteomics using UVPD extended to mega Dalton protein assemblies.
Native top-down mass spectrometry is emerging as a methodology that can be used to structurally investigate protein assemblies. To extend the possibilities of native top-down mass spectrometry to larger and more heterogeneous biomolecular assemblies, advances in both the mass analyzer and applied fragmentation techniques are still essential. Here, we explore ultraviolet photodissociation (UVPD) of protein assemblies on an Orbitrap with extended mass range, expanding its usage to large and heterogeneous macromolecular complexes, reaching masses above 1 million Da. We demonstrate that UVPD can lead not only to the ejection of intact subunits directly from such large intact complexes, but also to backbone fragmentation of these subunits, providing enough sequence information for subunit identification. The Orbitrap mass analyzer enables simultaneous monitoring of the precursor, the subunits, and the subunit fragments formed upon UVPD activation. While only partial sequence coverage of the subunits is observed, the UVPD data yields information about the localization of chromophores covalently attached to the subunits of the light harvesting complex B-phycoerythrin, extensive backbone fragmentation in a subunit of a CRISPR-Cas Csy (type I–F Cascade) complex, and sequence modifications in a virus-like proteinaceous nano-container. Through these multiple applications we demonstrate for the first time that UVPD based native top-down mass spectrometry is feasible for large and heterogeneous particles, including ribonucleoprotein complexes and MDa virus-like particles.
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Affiliation(s)
- Jean-François Greisch
- Biomolecular Mass Spectrometry and Proteomics , Bijvoet Center for Biomolecular Research , Utrecht Institute of Pharmaceutical Sciences , Utrecht University , Padualaan 8 , 3584 Utrecht , The Netherlands . .,Netherlands Proteomics Center , Padualaan 8 , 3584 Utrecht , The Netherlands
| | - Sem Tamara
- Biomolecular Mass Spectrometry and Proteomics , Bijvoet Center for Biomolecular Research , Utrecht Institute of Pharmaceutical Sciences , Utrecht University , Padualaan 8 , 3584 Utrecht , The Netherlands . .,Netherlands Proteomics Center , Padualaan 8 , 3584 Utrecht , The Netherlands
| | - Richard A Scheltema
- Biomolecular Mass Spectrometry and Proteomics , Bijvoet Center for Biomolecular Research , Utrecht Institute of Pharmaceutical Sciences , Utrecht University , Padualaan 8 , 3584 Utrecht , The Netherlands . .,Netherlands Proteomics Center , Padualaan 8 , 3584 Utrecht , The Netherlands
| | - Howard W R Maxwell
- Department of Microbiology and Immunology , University of Otago , PO Box 56 , 9054 Dunedin , New Zealand
| | - Robert D Fagerlund
- Department of Microbiology and Immunology , University of Otago , PO Box 56 , 9054 Dunedin , New Zealand
| | - Peter C Fineran
- Department of Microbiology and Immunology , University of Otago , PO Box 56 , 9054 Dunedin , New Zealand
| | - Stephan Tetter
- Laboratory of Organic Chemistry , Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1-5/10 , 8093 Zürich , Switzerland
| | - Donald Hilvert
- Laboratory of Organic Chemistry , Department of Chemistry and Applied Biosciences , ETH Zürich , Vladimir-Prelog-Weg 1-5/10 , 8093 Zürich , Switzerland
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics , Bijvoet Center for Biomolecular Research , Utrecht Institute of Pharmaceutical Sciences , Utrecht University , Padualaan 8 , 3584 Utrecht , The Netherlands . .,Netherlands Proteomics Center , Padualaan 8 , 3584 Utrecht , The Netherlands
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26
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Peters I, Metwally H, Konermann L. Mechanism of Electrospray Supercharging for Unfolded Proteins: Solvent-Mediated Stabilization of Protonated Sites During Chain Ejection. Anal Chem 2019; 91:6943-6952. [DOI: 10.1021/acs.analchem.9b01470] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Insa Peters
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Haidy Metwally
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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27
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Xia Z, Williams ER. Effect of droplet lifetime on where ions are formed in electrospray ionization. Analyst 2019; 144:237-248. [DOI: 10.1039/c8an01824c] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The location of gaseous ion formation in electrospray ionization under native mass spectrometry conditions was investigated using theta emitters with tip diameters between 317 nm and 4.4 μm to produce droplets with lifetimes between 1 and 50 μs.
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Affiliation(s)
- Zijie Xia
- Department of Chemistry
- University of California
- Berkeley
- USA
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28
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Konermann L, Metwally H, Duez Q, Peters I. Charging and supercharging of proteins for mass spectrometry: recent insights into the mechanisms of electrospray ionization. Analyst 2019; 144:6157-6171. [DOI: 10.1039/c9an01201j] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Molecular dynamics simulations have uncovered mechanistic details of the protein ESI process under various experimental conditions.
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Affiliation(s)
- Lars Konermann
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
| | - Haidy Metwally
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
| | - Quentin Duez
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
| | - Insa Peters
- Department of Chemistry
- The University of Western Ontario
- London
- Canada
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