1
|
Heel SV, Juen F, Bartosik K, Micura R, Kreutz C, Breuker K. Resolving the intricate binding of neomycin B to multiple binding motifs of a neomycin-sensing riboswitch aptamer by native top-down mass spectrometry and NMR spectroscopy. Nucleic Acids Res 2024; 52:4691-4701. [PMID: 38567725 PMCID: PMC11077050 DOI: 10.1093/nar/gkae224] [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] [Received: 08/07/2023] [Revised: 03/05/2024] [Accepted: 03/25/2024] [Indexed: 05/09/2024] Open
Abstract
Understanding small molecule binding to RNA can be complicated by an intricate interplay between binding stoichiometry, multiple binding motifs, different occupancies of different binding motifs, and changes in the structure of the RNA under study. Here, we use native top-down mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy to experimentally resolve these factors and gain a better understanding of the interactions between neomycin B and the 40 nt aptamer domain of a neomycin-sensing riboswitch engineered in yeast. Data from collisionally activated dissociation of the 1:1, 1:2 and 1:3 RNA-neomycin B complexes identified a third binding motif C of the riboswitch in addition to the two motifs A and B found in our previous study, and provided occupancies of the different binding motifs for each complex stoichiometry. Binding of a fourth neomycin B molecule was unspecific according to both MS and NMR data. Intriguingly, all major changes in the aptamer structure can be induced by the binding of the first neomycin B molecule regardless of whether it binds to motif A or B as evidenced by stoichiometry-resolved MS data together with titration data from 1H NMR spectroscopy in the imino proton region. Specific binding of the second and third neomycin B molecules further stabilizes the riboswitch aptamer, thereby allowing for a gradual response to increasing concentrations of neomycin B, which likely leads to a fine-tuning of the cellular regulatory mechanism.
Collapse
Affiliation(s)
- Sarah Viola Heel
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Fabian Juen
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Karolina Bartosik
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Christoph Kreutz
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| | - Kathrin Breuker
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria
| |
Collapse
|
2
|
Guzmán-Lorite M, Rosu F, Marina ML, García MC, Gabelica V. miRNA and DNA analysis by negative ion electron transfer dissociation and infrared multiple-photon dissociation mass spectrometry. Anal Chim Acta 2024; 1299:342431. [PMID: 38499418 DOI: 10.1016/j.aca.2024.342431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 02/15/2024] [Accepted: 02/26/2024] [Indexed: 03/20/2024]
Abstract
BACKGROUND The use of simple and hybrid fragmentation techniques for the identification of molecules in tandem mass spectrometry provides different and complementary information on the structure of molecules. Nevertheless, these techniques have not been as widely explored for oligonucleotides as for peptides or proteins. The analysis of microRNAs (miRNAs) warrants special attention, given their regulatory role and their relationship with several diseases. The application of different fragmentation techniques will be very interesting for their identification. RESULTS Four synthetic miRNAs and a DNA sequence were fragmented in an ESI-FT-ICR mass spectrometer using both simple and hybrid fragmentation techniques: CID, nETD followed by CID, IRMPD, and, for the first time, nETD in combination with IRMPD. The main fragmentation channel was base loss. The use of nETD-IRMPD resulted in d/z, a/w, and c/y ions at higher intensities. Moreover, nETD-IRMPD provided high sequence coverage and low internal fragmentation. Native MS analysis revealed that only miR159 and the DNA sequence formed stable dimers under physiological ionic strength. The use of organic co-solvents or additives resulted in a lower sequence coverage due to lesser overall ionization efficiency. NOVELTY This work demonstrates that the combination of nETD and IRMPD for miRNA fragmentation constitutes a suitable alternative to common fragmentation methods. This strategy resulted in efficient fragmentation of [miRNA]5- using low irradiation times and fewer internal fragments while ensuring a high sequence coverage. Moreover, given that such low charge states predominate upon spraying in physiological-like conditions, native MS can be applied for obtaining structural information at the same time.
Collapse
Affiliation(s)
- Miriam Guzmán-Lorite
- Universidad de Alcalá, Departamento de Química Analítica, Química Física e Ingeniería Química, Ctra. Madrid-Barcelona Km. 33.600, 28871, Alcalá de Henares (Madrid), Spain
| | - Frédéric Rosu
- Université de Bordeaux, CNRS, INSERM, IECB, UAR3033, US01, F-33600, Pessac, France
| | - María Luisa Marina
- Universidad de Alcalá, Departamento de Química Analítica, Química Física e Ingeniería Química, Ctra. Madrid-Barcelona Km. 33.600, 28871, Alcalá de Henares (Madrid), Spain; Universidad de Alcalá, Instituto de Investigación Química "Andrés M. Del Río", Ctra. Madrid-Barcelona Km. 33.600, 28871, Alcalá de Henares (Madrid), Spain
| | - María Concepción García
- Universidad de Alcalá, Departamento de Química Analítica, Química Física e Ingeniería Química, Ctra. Madrid-Barcelona Km. 33.600, 28871, Alcalá de Henares (Madrid), Spain; Universidad de Alcalá, Instituto de Investigación Química "Andrés M. Del Río", Ctra. Madrid-Barcelona Km. 33.600, 28871, Alcalá de Henares (Madrid), Spain.
| | - Valérie Gabelica
- Université de Bordeaux, CNRS, INSERM, IECB, UAR3033, US01, F-33600, Pessac, France; Université de Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600, Pessac, France
| |
Collapse
|
3
|
Penanes P, Gorshkov V, Ivanov MV, Gorshkov MV, Kjeldsen F. Potential of Negative-Ion-Mode Proteomics: An MS1-Only Approach. J Proteome Res 2023; 22:2734-2742. [PMID: 37395192 PMCID: PMC10407931 DOI: 10.1021/acs.jproteome.3c00307] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Indexed: 07/04/2023]
Abstract
Current proteomics approaches rely almost exclusively on using the positive ionization mode, resulting in inefficient ionization of many acidic peptides. This study investigates protein identification efficiency in the negative ionization mode using the DirectMS1 method. DirectMS1 is an ultrafast data acquisition method based on accurate peptide mass measurements and predicted retention times. Our method achieves the highest rate of protein identification in the negative ion mode to date, identifying over 1000 proteins in a human cell line at a 1% false discovery rate. This is accomplished using a single-shot 10 min separation gradient, comparable to lengthy MS/MS-based analyses. Optimizing separation and experimental conditions was achieved by utilizing mobile buffers containing 2.5 mM imidazole and 3% isopropanol. The study emphasized the complementary nature of data obtained in positive and negative ion modes. Combining the results from all replicates in both polarities increased the number of identified proteins to 1774. Additionally, we analyzed the method's efficiency using different proteases for protein digestion. Among the four studied proteases (LysC, GluC, AspN, and trypsin), trypsin and LysC demonstrated the highest protein identification yield. This suggests that digestion procedures utilized in positive-mode proteomics can be effectively applied in the negative ion mode. Data are deposited to ProteomeXchange: PXD040583.
Collapse
Affiliation(s)
- Pelayo
A. Penanes
- Department
of Biochemistry and Molecular Biology, University
of Southern Denmark, DK-5230 Odense M, Denmark
| | - Vladimir Gorshkov
- Department
of Biochemistry and Molecular Biology, University
of Southern Denmark, DK-5230 Odense M, Denmark
| | - Mark V. Ivanov
- V.
L. Talrose Institute for Energy Problems of Chemical Physics, N. N. Semenov Federal Research Center for Chemical
Physics, Russian Academy of Sciences, 38 Leninsky Pr., Bld. 2, Moscow 119334, Russia
| | - Mikhail V. Gorshkov
- V.
L. Talrose Institute for Energy Problems of Chemical Physics, N. N. Semenov Federal Research Center for Chemical
Physics, Russian Academy of Sciences, 38 Leninsky Pr., Bld. 2, Moscow 119334, Russia
| | - Frank Kjeldsen
- Department
of Biochemistry and Molecular Biology, University
of Southern Denmark, DK-5230 Odense M, Denmark
| |
Collapse
|
4
|
Santos IC, Lanzillotti M, Shilov I, Basanta-Sanchez M, Roushan A, Lawler R, Tang W, Bern M, Brodbelt JS. Ultraviolet Photodissociation and Activated Electron Photodetachment Mass Spectrometry for Top-Down Sequencing of Modified Oligoribonucleotides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:510-520. [PMID: 35157441 DOI: 10.1021/jasms.1c00340] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
With the increased development of new RNA-based therapeutics, the need for robust analytical methods for confirming sequences and mapping modifications has accelerated. Characterizing modified ribonucleic acids using mass spectrometry is challenging because diagnostic fragmentation may be suppressed for modified nucleotides, thus hampering complete sequence coverage and the confident localization of modifications. Ultraviolet photodissociation (UVPD) has shown great potential for the characterization of nucleic acids due to extensive backbone fragmentation. Activated electron photodetachment dissociation (a-EPD) has also been used as an alternative to capitalize on the dominant charge-reduction pathway prevalent in UVPD, facilitate dissociation, and produce high abundances of fragment ions. Here, we compare higher-energy collisional activation (HCD), UVPD using 193 and 213 nm photons, and a-EPD for the top-down sequencing of modified nucleic acids, including methylated, phosphorothioate, and locked nucleic acid-modified DNA. The presence of these modifications alters the fragmentation pathways observed upon UVPD and a-EPD, and extensive backbone cleavage is observed that results in the production of fragment ions that retain the modifications and allow them to be pinpointed. LNA and 2'-O-methoxy phosphorothioate modifications caused a significant suppression of fragmentation for UVPD but not for a-EPD, whereas phosphorothioate bonds did not cause any significant suppression for either method. The incorporation of 2'-O-methyl modifications suppressed fragmentation of the antisense strand of patisiran, which resulted in some gaps in sequence coverage. However, UVPD provided the highest sequence coverage when compared to a-EPD.
Collapse
Affiliation(s)
- Inês C Santos
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Michael Lanzillotti
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Ignat Shilov
- Protein Metrics Inc., 20863 Stevens Creek Boulevard, Cupertino, California 95014, United States
| | - Maria Basanta-Sanchez
- Protein Metrics Inc., 20863 Stevens Creek Boulevard, Cupertino, California 95014, United States
| | - Abhishek Roushan
- Protein Metrics Inc., 20863 Stevens Creek Boulevard, Cupertino, California 95014, United States
| | - Rose Lawler
- Protein Metrics Inc., 20863 Stevens Creek Boulevard, Cupertino, California 95014, United States
| | - Wilfred Tang
- Protein Metrics Inc., 20863 Stevens Creek Boulevard, Cupertino, California 95014, United States
| | - Marshall Bern
- Protein Metrics Inc., 20863 Stevens Creek Boulevard, Cupertino, California 95014, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| |
Collapse
|
5
|
Largy E, König A, Ghosh A, Ghosh D, Benabou S, Rosu F, Gabelica V. Mass Spectrometry of Nucleic Acid Noncovalent Complexes. Chem Rev 2021; 122:7720-7839. [PMID: 34587741 DOI: 10.1021/acs.chemrev.1c00386] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nucleic acids have been among the first targets for antitumor drugs and antibiotics. With the unveiling of new biological roles in regulation of gene expression, specific DNA and RNA structures have become very attractive targets, especially when the corresponding proteins are undruggable. Biophysical assays to assess target structure as well as ligand binding stoichiometry, affinity, specificity, and binding modes are part of the drug development process. Mass spectrometry offers unique advantages as a biophysical method owing to its ability to distinguish each stoichiometry present in a mixture. In addition, advanced mass spectrometry approaches (reactive probing, fragmentation techniques, ion mobility spectrometry, ion spectroscopy) provide more detailed information on the complexes. Here, we review the fundamentals of mass spectrometry and all its particularities when studying noncovalent nucleic acid structures, and then review what has been learned thanks to mass spectrometry on nucleic acid structures, self-assemblies (e.g., duplexes or G-quadruplexes), and their complexes with ligands.
Collapse
Affiliation(s)
- Eric Largy
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Alexander König
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Anirban Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Debasmita Ghosh
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Sanae Benabou
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| | - Frédéric Rosu
- Univ. Bordeaux, CNRS, INSERM, IECB, UMS 3033, F-33600 Pessac, France
| | - Valérie Gabelica
- Univ. Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, IECB, F-33600 Pessac, France
| |
Collapse
|
6
|
Santos IC, Brodbelt JS. Recent developments in the characterization of nucleic acids by liquid chromatography, capillary electrophoresis, ion mobility, and mass spectrometry (2010-2020). J Sep Sci 2021; 44:340-372. [PMID: 32974962 PMCID: PMC8378248 DOI: 10.1002/jssc.202000833] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/25/2022]
Abstract
The development of new strategies for the analysis of nucleic acids has gained momentum due to the increased interest in using these biomolecules as drugs or drug targets. The application of new mass spectrometry ion activation techniques and the optimization of separation methods including liquid chromatography, capillary electrophoresis, and ion mobility have allowed more detailed characterization of nucleic acids and oligonucleotide therapeutics including confirmation of sequence, localization of modifications and interaction sites, and structural analysis as well as identification of failed sequences and degradation products. This review will cover tandem mass spectrometry methods as well as the recent developments in liquid chromatography, capillary electrophoresis, and ion mobility coupled to mass spectrometry for the analysis of nucleic acids and oligonucleotides.
Collapse
Affiliation(s)
- Inês C Santos
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | | |
Collapse
|
7
|
Native mass spectrometry reveals the initial binding events of HIV-1 rev to RRE stem II RNA. Nat Commun 2020; 11:5750. [PMID: 33188169 PMCID: PMC7666190 DOI: 10.1038/s41467-020-19144-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 09/29/2020] [Indexed: 11/24/2022] Open
Abstract
Nuclear export complexes composed of rev response element (RRE) ribonucleic acid (RNA) and multiple molecules of rev protein are promising targets for the development of therapeutic strategies against human immunodeficiency virus type 1 (HIV-1), but their assembly remains poorly understood. Using native mass spectrometry, we show here that rev initially binds to the upper stem of RRE IIB, from where it is relayed to binding sites that allow for rev dimerization. The newly discovered binding region implies initial rev recognition by nucleotides that are not part of the internal loop of RRE stem IIB RNA, which was previously identified as the preferred binding region. Our study highlights the unique capability of native mass spectrometry to separately study the binding interfaces of RNA/protein complexes of different stoichiometry, and provides a detailed understanding of the mechanism of RRE/rev association with implications for the rational design of potential drugs against HIV-1 infection. The HIV-1 RNA-binding protein rev facilitates nuclear export of viral RNA. Here, the authors use native mass spectrometry to study the interactions between rev-derived peptides and rev response elements of HIV-1 RNA, providing mechanistic insights into rev recognition and recruitment.
Collapse
|
8
|
Peters-Clarke TM, Quan Q, Brademan DR, Hebert AS, Westphall MS, Coon JJ. Ribonucleic Acid Sequence Characterization by Negative Electron Transfer Dissociation Mass Spectrometry. Anal Chem 2020; 92:4436-4444. [PMID: 32091202 PMCID: PMC7161943 DOI: 10.1021/acs.analchem.9b05388] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Modified oligonucleotides represent a promising avenue for drug development, with small interfering RNAs (siRNA) and microRNAs gaining traction in the therapeutic market. Mass spectrometry (MS)-based analysis offers many benefits for characterizing modified nucleic acids. Negative electron transfer dissociation (NETD) has proven valuable in sequencing oligonucleotide anions, particularly because it can retain modifications while generating sequence-informative fragments. We show that NETD can be successfully implemented on a widely available quadrupole-Orbitrap-linear ion trap mass spectrometer that uses a front-end glow discharge source to generate radical fluoranthene reagent cations. We characterize both unmodified and modified ribonucleic acids and present the first application of activated-ion negative electron transfer dissociation (AI-NETD) to nucleic acids. AI-NETD achieved 100% sequence coverage for both a 6-mer (5'-rGmUrArCmUrG-3') with 2'-O-methyl modifications and a 21-mer (5'-rCrArUrCrCrUrCrUrArGrArGrGrArUrArGrArArUrG-3'), the luciferase antisense siRNA. Both NETD and AI-NETD afforded complete sequence coverage of these molecules while maintaining a relatively low degree of undesired base-loss products and internal products relative to collision-based methods.
Collapse
Affiliation(s)
| | - Qiuwen Quan
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Dain R. Brademan
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | | | | | - Joshua J. Coon
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| |
Collapse
|
9
|
Oligonucleotide analysis by hydrophilic interaction liquid chromatography-mass spectrometry in the absence of ion-pair reagents. J Chromatogr A 2019; 1595:39-48. [PMID: 30772056 DOI: 10.1016/j.chroma.2019.02.016] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 02/02/2019] [Accepted: 02/06/2019] [Indexed: 01/09/2023]
Abstract
Improving our understanding of nucleic acids, both in biological and synthetic applications, remains a bustling area of research for both academic and industrial laboratories. As nucleic acids research evolves, so must the analytical techniques used to characterize nucleic acids. One powerful analytical technique has been coupled liquid chromatography - tandem mass spectrometry (LC-MS/MS). To date, the most successful chromatographic mode has been ion-pairing reversed-phase liquid chromatography. Hydrophilic interaction liquid chromatography (HILIC), in the absence of ion-pair reagents, has been investigated here as an alternative chromatographic approach to the analysis of oligonucleotides. By combining a mobile phase system using commonly employed in liquid chromatography-mass spectrometry (LC-MS) - i.e., water, acetonitrile, and ammonium acetate - and a new, commercially available diol-based HILIC column, high chromatographic and mass spectrometric performance for a wide range of oligonucleotides is demonstrated. Particular applications of HILIC-MS for the analysis of deoxynucleic acid (DNA) oligomers, modified and unmodified oligoribonucleotides, and phosphorothioate DNA oligonucleotides are presented. Based on the LC-MS performance, this HILIC-based approach provides an attractive, sensitive and robust alternative to prior ion-pairing dependent methods with potential utility for both qualitative and quantitative analyses of oligonucleotides without compromising chromatographic or mass spectrometric performance.
Collapse
|
10
|
Vušurović J, Breuker K. Relative Strength of Noncovalent Interactions and Covalent Backbone Bonds in Gaseous RNA-Peptide Complexes. Anal Chem 2019; 91:1659-1664. [PMID: 30614682 PMCID: PMC6335609 DOI: 10.1021/acs.analchem.8b05387] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Interactions of ribonucleic acids (RNA) with basic ligands such as proteins or aminoglycosides play a key role in fundamental biological processes. Native top-down mass spectrometry (MS) has recently been extended to binding site mapping of RNA-ligand interactions by collisionally activated dissociation, without the need for laborious sample preparation procedures. The technique relies on the preservation of noncovalent interactions at energies that are sufficiently high to cause RNA backbone cleavage. In this study, we address the question of how many and what types of noncovalent interactions allow for binding site mapping by top-down MS. We show that proton transfer from protonated ligand to deprotonated RNA within salt bridges initiates loss of the ligand, but that proton transfer becomes energetically unfavorable in the presence of additional hydrogen bonds such that the noncovalent interactions remain stronger than the covalent RNA backbone bonds.
Collapse
Affiliation(s)
- Jovana Vušurović
- Institut für Organische Chemie and Center for Molecular Biosciences Innsbruck (CMBI) , Universität Innsbruck , Innrain 80-82 , 6020 Innsbruck , Austria
| | - Kathrin Breuker
- Institut für Organische Chemie and Center for Molecular Biosciences Innsbruck (CMBI) , Universität Innsbruck , Innrain 80-82 , 6020 Innsbruck , Austria
| |
Collapse
|
11
|
Schneeberger EM, Breuker K. Replacing H + by Na + or K + in phosphopeptide anions and cations prevents electron capture dissociation. Chem Sci 2018; 9:7338-7353. [PMID: 30542537 PMCID: PMC6237128 DOI: 10.1039/c8sc02470g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 07/07/2018] [Indexed: 01/29/2023] Open
Abstract
By successively replacing H+ by Na+ or K+ in phosphopeptide anions and cations, we show that the efficiency of fragmentation into c and z˙ or c˙ and z fragments from N-Cα backbone bond cleavage by negative ion electron capture dissociation (niECD) and electron capture dissociation (ECD) substantially decreases with increasing number of alkali ions attached. In proton-deficient phosphopeptide ions with a net charge of 2-, we observed an exponential decrease in electron capture efficiency with increasing number of Na+ or K+ ions attached, suggesting that electrons are preferentially captured at protonated sites. In proton-abundant phosphopeptide ions with a net charge of 3+, the electron capture efficiency was not affected by replacing up to four H+ ions with Na+ or K+ ions, but the yield of c, z˙ and c˙, z fragments from N-Cα backbone bond cleavage generally decreased next to Na+ or K+ binding sites. We interpret the site-specific decrease in fragmentation efficiency as Na+ or K+ binding to backbone amide oxygen in competition with interactions of protonated sites that would otherwise lead to backbone cleavage into c, z˙ or c˙, z fragments. Our findings seriously challenge the hypothesis that the positive charge responsible for ECD into c, z˙ or c˙, z fragments can generally be a sodium or other metal ion instead of a proton.
Collapse
Affiliation(s)
- Eva-Maria Schneeberger
- Institute of Organic Chemistry , Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80/82 , 6020 Innsbruck , Austria . ; http://www.bioms-breuker.at/
| | - Kathrin Breuker
- Institute of Organic Chemistry , Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80/82 , 6020 Innsbruck , Austria . ; http://www.bioms-breuker.at/
| |
Collapse
|
12
|
Vušurović J, Schneeberger E, Breuker K. Interactions of Protonated Guanidine and Guanidine Derivatives with Multiply Deprotonated RNA Probed by Electrospray Ionization and Collisionally Activated Dissociation. ChemistryOpen 2017; 6:739-750. [PMID: 29226062 PMCID: PMC5715244 DOI: 10.1002/open.201700143] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/06/2017] [Indexed: 11/25/2022] Open
Abstract
Interactions of ribonucleic acid (RNA) with guanidine and guanidine derivatives are important features in RNA-protein and RNA-drug binding. Here we have investigated noncovalently bound complexes of an 8-nucleotide RNA and six different ligands, all of which have a guanidinium moiety, by using electrospray ionization (ESI) and collisionally activated dissociation (CAD) mass spectrometry (MS). The order of complex stability correlated almost linearly with the number of ligand atoms that can potentially be involved in hydrogen-bond or salt-bridge interactions with the RNA, but not with the proton affinity of the ligands. However, ligand dissociation of the complex ions in CAD was generally accompanied by proton transfer from ligand to RNA, which indicated conversion of salt-bridge into hydrogen-bond interactions. The relative stabilities and dissociation pathways of [RNA+m L-n H] n- complexes with different stoichiometries (m=1-5) and net charge (n= 2-5) revealed both specific and unspecific ligand binding to the RNA.
Collapse
Affiliation(s)
- Jovana Vušurović
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Eva‐Maria Schneeberger
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| | - Kathrin Breuker
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI)University of InnsbruckInnrain 80–826020InnsbruckAustria
| |
Collapse
|
13
|
Glasner H, Riml C, Micura R, Breuker K. Label-free, direct localization and relative quantitation of the RNA nucleobase methylations m6A, m5C, m3U, and m5U by top-down mass spectrometry. Nucleic Acids Res 2017; 45:8014-8025. [PMID: 28549193 PMCID: PMC5570050 DOI: 10.1093/nar/gkx470] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 05/23/2017] [Indexed: 01/28/2023] Open
Abstract
Nucleobase methylations are ubiquitous posttranscriptional modifications of ribonucleic acids (RNA) that can substantially increase the structural diversity of RNA in a highly dynamic fashion with implications for gene expression and human disease. However, high throughput, deep sequencing does not generally provide information on posttranscriptional modifications (PTMs). A promising alternative approach for the characterization of PTMs, i.e. their identification, localization, and relative quantitation, is top-down mass spectrometry (MS). In this study, we have investigated how specific nucleobase methylations affect RNA ionization in electrospray ionization (ESI), and backbone cleavage in collisionally activated dissociation (CAD) and electron detachment dissociation (EDD). For this purpose, we have developed two new approaches for the characterization of RNA methylations in mixtures of either isomers of RNA or nonisomeric RNA forms. Fragment ions from dissociation experiments were analyzed to identify the modification type, to localize the modification sites, and to reveal the site-specific, relative extent of modification for each site.
Collapse
Affiliation(s)
- Heidelinde Glasner
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Christian Riml
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Kathrin Breuker
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| |
Collapse
|
14
|
Steinkoenig J, Cecchini MM, Reale S, Goldmann AS, Barner-Kowollik C. Supercharging Synthetic Polymers: Mass Spectrometric Access to Nonpolar Synthetic Polymers. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b02018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Jan Steinkoenig
- School
of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), 2 George St., QLD
4000, Brisbane, Australia
- Macromolecular
Architectures, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76128 Eggenstein-Leopoldshafen, Germany
- Institut für Biologische
Grenzflächen, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Martina M. Cecchini
- Dipartimento
di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, Via Vetoio, Coppito, 67100 L’Aquila, Italy
| | - Samantha Reale
- Dipartimento
di Scienze Fisiche e Chimiche, Università degli Studi dell’Aquila, Via Vetoio, Coppito, 67100 L’Aquila, Italy
| | - Anja S. Goldmann
- School
of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), 2 George St., QLD
4000, Brisbane, Australia
- Macromolecular
Architectures, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76128 Eggenstein-Leopoldshafen, Germany
- Institut für Biologische
Grenzflächen, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Christopher Barner-Kowollik
- School
of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), 2 George St., QLD
4000, Brisbane, Australia
- Macromolecular
Architectures, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology (KIT), Engesserstr. 18, 76128 Eggenstein-Leopoldshafen, Germany
- Institut für Biologische
Grenzflächen, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| |
Collapse
|
15
|
Roman GT, Murphy JP. Improving sensitivity and linear dynamic range of intact protein analysis using a robust and easy to use microfluidic device. Analyst 2017; 142:1073-1083. [DOI: 10.1039/c6an02518h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We demonstrate an integrated microfluidic LC device coupled to a QTOF capable of improving sensitivity and linearity for intact protein analysis while also tuning the charge state distributions (CSD) of whole antibodies.
Collapse
|
16
|
Schürch S. Characterization of nucleic acids by tandem mass spectrometry - The second decade (2004-2013): From DNA to RNA and modified sequences. MASS SPECTROMETRY REVIEWS 2016; 35:483-523. [PMID: 25288464 DOI: 10.1002/mas.21442] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 05/04/2014] [Accepted: 05/04/2014] [Indexed: 06/03/2023]
Abstract
Nucleic acids play key roles in the storage and processing of genetic information, as well as in the regulation of cellular processes. Consequently, they represent attractive targets for drugs against gene-related diseases. On the other hand, synthetic oligonucleotide analogues have found application as chemotherapeutic agents targeting cellular DNA and RNA. The development of effective nucleic acid-based chemotherapeutic strategies requires adequate analytical techniques capable of providing detailed information about the nucleotide sequences, the presence of structural modifications, the formation of higher-order structures, as well as the interaction of nucleic acids with other cellular components and chemotherapeutic agents. Due to the impressive technical and methodological developments of the past years, tandem mass spectrometry has evolved to one of the most powerful tools supporting research related to nucleic acids. This review covers the literature of the past decade devoted to the tandem mass spectrometric investigation of nucleic acids, with the main focus on the fundamental mechanistic aspects governing the gas-phase dissociation of DNA, RNA, modified oligonucleotide analogues, and their adducts with metal ions. Additionally, recent findings on the elucidation of nucleic acid higher-order structures by tandem mass spectrometry are reviewed. © 2014 Wiley Periodicals, Inc., Mass Spec Rev 35:483-523, 2016.
Collapse
Affiliation(s)
- Stefan Schürch
- Department of Chemistry and Biochemistry, University of Bern, CH-3012, Bern, Switzerland
| |
Collapse
|
17
|
Liigand P, Kaupmees K, Kruve A. Ionization Efficiency of Doubly Charged Ions Formed from Polyprotic Acids in Electrospray Negative Mode. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1211-8. [PMID: 27044024 DOI: 10.1007/s13361-016-1384-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/03/2016] [Accepted: 03/14/2016] [Indexed: 05/25/2023]
Abstract
The ability of polyprotic acids to give doubly charged ions in negative mode electrospray was studied and related to physicochemical properties of the acids via linear discriminant analysis (LDA). It was discovered that the compound has to be strongly acidic (low pK a1 and pK a2) and to have high hydrophobicity (logP ow) to become multiply charged. Ability to give multiply charged ions in ESI/MS cannot be directly predicted from the solution phase acidities. Therefore, for the first time, a quantitative model to predict the charge state of the analyte in ESI/MS is proposed and validated for small anions. Also, a model to predict ionization efficiencies of these analytes was developed. Results indicate that acidity of the analyte, its octanol-water partition coefficient, and charge delocalization are important factors that influence ionization efficiencies as well as charge states of the analytes. The pH of the solvent was also found to be an important factor influencing the ionization efficiency of doubly charged ions. Graphical Abstract ᅟ.
Collapse
Affiliation(s)
- Piia Liigand
- Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia.
| | - Karl Kaupmees
- Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia
| | - Anneli Kruve
- Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia
| |
Collapse
|
18
|
Riley NM, Rush MJP, Rose CM, Richards AL, Kwiecien NW, Bailey DJ, Hebert AS, Westphall MS, Coon JJ. The Negative Mode Proteome with Activated Ion Negative Electron Transfer Dissociation (AI-NETD). Mol Cell Proteomics 2015; 14:2644-60. [PMID: 26193884 DOI: 10.1074/mcp.m115.049726] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Indexed: 01/15/2023] Open
Abstract
The field of proteomics almost uniformly relies on peptide cation analysis, leading to an underrepresentation of acidic portions of proteomes, including relevant acidic posttranslational modifications. Despite the many benefits negative mode proteomics can offer, peptide anion analysis remains in its infancy due mainly to challenges with high-pH reversed-phase separations and a lack of robust fragmentation methods suitable for peptide anion characterization. Here, we report the first implementation of activated ion negative electron transfer dissociation (AI-NETD) on the chromatographic timescale, generating 7,601 unique peptide identifications from Saccharomyces cerevisiae in single-shot nLC-MS/MS analyses of tryptic peptides-a greater than 5-fold increase over previous results with NETD alone. These improvements translate to identification of 1,106 proteins, making this work the first negative mode study to identify more than 1,000 proteins in any system. We then compare the performance of AI-NETD for analysis of peptides generated by five proteases (trypsin, LysC, GluC, chymotrypsin, and AspN) for negative mode analyses, identifying as many as 5,356 peptides (1,045 proteins) with LysC and 4,213 peptides (857 proteins) with GluC in yeast-characterizing 1,359 proteins in total. Finally, we present the first deep-sequencing approach for negative mode proteomics, leveraging offline low-pH reversed-phase fractionation prior to online high-pH separations and peptide fragmentation with AI-NETD. With this platform, we identified 3,467 proteins in yeast with trypsin alone and characterized a total of 3,730 proteins using multiple proteases, or nearly 83% of the expressed yeast proteome. This work represents the most extensive negative mode proteomics study to date, establishing AI-NETD as a robust tool for large-scale peptide anion characterization and making the negative mode approach a more viable platform for future proteomic studies.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Joshua J Coon
- From the ‡Department of Chemistry, §Genome Center, and ¶Department of Biomolecular Chemistry University of Wisconsin, Madison, Wisconsin, 53706
| |
Collapse
|
19
|
Riml C, Glasner H, Rodgers MT, Micura R, Breuker K. On the mechanism of RNA phosphodiester backbone cleavage in the absence of solvent. Nucleic Acids Res 2015; 43:5171-81. [PMID: 25904631 PMCID: PMC4446422 DOI: 10.1093/nar/gkv288] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/24/2015] [Indexed: 12/18/2022] Open
Abstract
Ribonucleic acid (RNA) modifications play an important role in the regulation of gene expression and the development of RNA-based therapeutics, but their identification, localization and relative quantitation by conventional biochemical methods can be quite challenging. As a promising alternative, mass spectrometry (MS) based approaches that involve RNA dissociation in ‘top-down’ strategies are currently being developed. For this purpose, it is essential to understand the dissociation mechanisms of unmodified and posttranscriptionally or synthetically modified RNA. Here, we have studied the effect of select nucleobase, ribose and backbone modifications on phosphodiester bond cleavage in collisionally activated dissociation (CAD) of positively and negatively charged RNA. We found that CAD of RNA is a stepwise reaction that is facilitated by, but does not require, the presence of positive charge. Preferred backbone cleavage next to adenosine and guanosine in CAD of (M+nH)n+ and (M−nH)n− ions, respectively, is based on hydrogen bonding between nucleobase and phosphodiester moieties. Moreover, CAD of RNA involves an intermediate that is sufficiently stable to survive extension of the RNA structure and intramolecular proton redistribution according to simple Coulombic repulsion prior to backbone cleavage into c and y ions from phosphodiester bond cleavage.
Collapse
Affiliation(s)
- Christian Riml
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Heidelinde Glasner
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - M T Rodgers
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202-3489, United States
| | - Ronald Micura
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Kathrin Breuker
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| |
Collapse
|
20
|
Douglass KA, Venter AR. On the role of a direct interaction between protein ions and solvent additives during protein supercharging by electrospray ionization mass spectrometry. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2015; 21:641-647. [PMID: 26307743 DOI: 10.1255/ejms.1360] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The addition of certain reagents during the electrospray ionization mass spectrometry of proteins can shift the protein ion signal charge-state distributions (CSDs) to higher average charge states, a phenomenon known as 'supercharging'. The role of reagent gas-phase basicity (GB) during this process was investigated in both the negative and positive ion modes. Reagents with known or calculated GBs were added individually in equimolar amounts to protein solutions which were subsequently electrosprayed for mass spectrometry analysis. Shifts in the CSDs of the protein ion signals were monitored and related to the reagents' GBs. Trends for this data were evaluated for possible insights into a supercharging mechanism involving the direct interaction between supercharging reagent and protein ion. Reagent GB was confirmed to be directly related to the amount of supercharging observed in the negative ion mode. Supercharging in the positive ion mode, on the other hand, showed a maximal trend. Interestingly, a loss of signal and supercharging efficacy was observed for reagents with GBs intermediate within the investigated range, between ~800 and ~840 kJ mol(-1), at the 100 mM concentration used in the present study. The possibility of a direct interaction model for supercharging in the negative and positive ion modes dependent on the GBs of the protein ions and reagents is discussed. In the positive ion mode, supercharging appears to depend on the stability of a proton bridge formed between the reagent and a highly charged protein ion.
Collapse
Affiliation(s)
- Kevin A Douglass
- Department of Chemistry, Western Michigan University, 1903 W Michigan Ave, Kalamazoo, MI 49008-5413, United States.
| | - Andre R Venter
- D epartment of Chemistry, Western Michigan University, 1903 W Michigan Ave, Kalamazoo, MI 49008-5413, United States.
| |
Collapse
|
21
|
Ogorzalek Loo RR, Lakshmanan R, Loo JA. What protein charging (and supercharging) reveal about the mechanism of electrospray ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1675-93. [PMID: 25135609 PMCID: PMC4163133 DOI: 10.1007/s13361-014-0965-1] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 06/13/2014] [Accepted: 07/08/2014] [Indexed: 05/11/2023]
Abstract
Understanding the charging mechanism of electrospray ionization is central to overcoming shortcomings such as ion suppression or limited dynamic range, and explaining phenomena such as supercharging. Towards that end, we explore what accumulated observations reveal about the mechanism of electrospray. We introduce the idea of an intermediate region for electrospray ionization (and other ionization methods) to account for the facts that solution charge state distributions (CSDs) do not correlate with those observed by ESI-MS (the latter bear more charge) and that gas phase reactions can reduce, but not increase, the extent of charging. This region incorporates properties (e.g., basicities) intermediate between solution and gas phase. Assuming that droplet species polarize within the high electric field leads to equations describing ion emission resembling those from the equilibrium partitioning model. The equations predict many trends successfully, including CSD shifts to higher m/z for concentrated analytes and shifts to lower m/z for sprays employing smaller emitter opening diameters. From this view, a single mechanism can be formulated to explain how reagents that promote analyte charging ("supercharging") such as m-NBA, sulfolane, and 3-nitrobenzonitrile increase analyte charge from "denaturing" and "native" solvent systems. It is suggested that additives' Brønsted basicities are inversely correlated to their ability to shift CSDs to lower m/z in positive ESI, as are Brønsted acidities for negative ESI. Because supercharging agents reduce an analyte's solution ionization, excess spray charge is bestowed on evaporating ions carrying fewer opposing charges. Brønsted basicity (or acidity) determines how much ESI charge is lost to the agent (unavailable to evaporating analyte).
Collapse
Affiliation(s)
- Rachel R Ogorzalek Loo
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, University of California-Los Angeles, Los Angeles, CA, 90095, USA,
| | | | | |
Collapse
|
22
|
Doussineau T, Santacreu M, Antoine R, Dugourd P, Zhang W, Chaduc I, Lansalot M, D'Agosto F, Charleux B. The Charging of Micellar Nanoparticles in Electrospray Ionization. Chemphyschem 2013; 14:603-9. [DOI: 10.1002/cphc.201200777] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 12/11/2012] [Indexed: 11/05/2022]
|
23
|
Taucher M, Breuker K. Characterization of modified RNA by top-down mass spectrometry. Angew Chem Int Ed Engl 2012; 51:11289-92. [PMID: 23042528 PMCID: PMC3532624 DOI: 10.1002/anie.201206232] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Indexed: 11/11/2022]
Abstract
Characteristic mass differences between fragment ions from backbone cleavage of RNA by electron detachment (d, w) and fragment ions from collisionally activated dissociation (c, y) provide extensive sequence information. Structure analysis by this approach should be especially useful for the detailed characterization of synthetic or post-transcriptionally modified RNA.
Collapse
Affiliation(s)
- Monika Taucher
- Institut für Organische Chemie and Center for Molecular Biosciences Innsbruck (CMBI), Universität InnsbruckInnrain 80–82, 6020 Innsbruck (Austria)
| | - Kathrin Breuker
- Institut für Organische Chemie and Center for Molecular Biosciences Innsbruck (CMBI), Universität InnsbruckInnrain 80–82, 6020 Innsbruck (Austria)
| |
Collapse
|
24
|
Taucher M, Breuker K. Characterization of Modified RNA by Top-Down Mass Spectrometry. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201206232] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
25
|
Girod M, Antoine R, Dugourd P, Love C, Mordehai A, Stafford G. Basic vapor exposure for tuning the charge state distribution of proteins in negative electrospray ionization: elucidation of mechanisms by fluorescence spectroscopy. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1221-1231. [PMID: 22565506 DOI: 10.1007/s13361-012-0375-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/09/2012] [Accepted: 03/12/2012] [Indexed: 05/31/2023]
Abstract
Manipulation for simplifying or increasing the observed charge state distributions of proteins can be highly desirable in mass spectrometry experiments. In the present work, we implemented a vapor introduction technique to an Agilent Jet Stream ESI (Agilent Technologies, Santa Clara, CA, USA) source. An apparatus was designed to allow for the enrichment of the nitrogen sheath gas with basic vapors. An optical setup, using laser-induced fluorescence and a pH-chromic dye, permits the pH profiling of the droplets as they evaporate in the electrospray plume. Mechanisms of pH droplet modification and its effect on the protein charging phenomenon are elucidated. An important finding is that the enrichment with basic vapors of the nitrogen sheath gas, which surrounds the nebulizer spray, leads to an increase in the spray current. This is attributed to an increase in the electrical conductivity of water-amine enriched solvent at the tip exit. Here, the increased current results in a generation of additional electrolytically produced OH(-) ions and a corresponding increase in the pH at the tip exit. Along the electrospray plume, the pH of the droplets increases due to both droplet evaporation and exposure to basic vapors from the seeded sheath gas. The pH evolution in the ESI plume obtained using pure and basic seeded sheath gas was correlated with the evolution of the charge state distribution observed in mass spectra of proteins, in the negative ion mode. Taking advantage of the Agilent Jet Stream source geometry, similar protein charge state distributions and ion intensities obtained with basic initial solutions, can be obtained using native solution conditions by seeding the heated sheath gas with basic vapors.
Collapse
Affiliation(s)
- Marion Girod
- Laboratoire de Spectrométrie Ionique et Moléculaire Villeurbanne, France, Université de Lyon, 69622, Lyon, France
| | | | | | | | | | | |
Collapse
|