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Gorbachev V, Miloglyadova L, Chen P. An automatic variable laser power attenuator for continuous-wave quantum cascade lasers in cryogenic ion vibrational predissociation spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:093002. [PMID: 39240148 DOI: 10.1063/5.0189140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 08/13/2024] [Indexed: 09/07/2024]
Abstract
Cryogenic ion vibrational predissociation (CIVP) spectroscopy is an established and valuable technique for molecular elucidation in the gas phase. CIVP relies on tunable lasers, wherein among typical laser schemes, the application of mid-infrared continuous-wave quantum cascade laser (cw-QCL) is the most robust and elegant solution, as we have recently demonstrated. However, potential challenges arise from an inhomogeneous character across laser power tuning curves. A large laser power output could have undesired consequences, such as multiphoton absorption or saturation effects. Significant variations in laser power tuning curves could potentially alter the shape of the investigated band, particularly for diffuse bands. In this study, we have developed and introduced an automatic variable laser power attenuator designed to keep the laser power output uniform at a user-defined value across the entire available spectral range. We demonstrated the application of this attenuator in obtaining CIVP spectra of a model compound with a diffuse N-H-N band. This approach enhances the reliability of measuring diffuse bands and overall applicability of cw-QCL.
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Affiliation(s)
- Vladimir Gorbachev
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Larisa Miloglyadova
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
| | - Peter Chen
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland
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2
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Meddeb-Limem S, Ben Fredj A. Computational study of the dimerization of glyphosate: mechanism and effect of solvent. RSC Adv 2024; 14:23184-23203. [PMID: 39045405 PMCID: PMC11264236 DOI: 10.1039/d4ra04300f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Accepted: 07/09/2024] [Indexed: 07/25/2024] Open
Abstract
A computational study on the structure and stability of different series of glyphosate (Glyph) dimers comprising nonionized (N) and zwitterionic structures (Z) for neutral monomers, followed by an analysis of energetics of Glyph dimerization process have been performed by means of quantum chemical calculations in different media. Optimized geometries for energy minima, as well as relative potential and free energies of the possible various conformers of each series of Glyph dimer were computed as a function of the medium at B3LYP-D3/6-311++G(2d,2p) level. The solvation model based on density (SMD) is employed for all solution phase computations. Non-ionized dimers (DN), anion-cation (AC) and either zwitterion-zwitterion (DZP and DZC) or non-ionized-phosphonate zwitterion (NZP) ionized neutral forms of Glyph dimer are predicted to exist in the gas phase and in solution in large contrast to Glyph monomers. The DZC dimer form exhibiting a centrosymmetric arrangement of two carboxylate zwitterion units was found to be the most stable dimer structure in all media. In aqueous solution, the DZP and AC dimer type structures are significantly stabilized by hydration. The tautomerisms between DZC, DZP and AC dimer type structures have been investigated in the gas phase and in solution. The DZC type structures are more prone to experience proton transfer in water than in the gas phase and in cyclohexane. The mechanism for the tautomerization process in neutral ionized Glyph dimers proceeds via two direct proton transfer paths: DZP ⇋ AC ⇋ DZC. Results show that solvents play a key role in modulating the energetics of the dimerization process of Glyph. Solvation in cyclohexane, favors the dimerization process however, hydration opposed it. In aqueous solution, the mechanism of the dimerization of Glyph from its phosphonate zwitterionic monomer form (ZP) could be described by a set of equilibria including direct proton transfer paths as follows: 2ZP ⇋ DZP ⇋ AC ⇋ DZC. According to our results, in aqueous solution, DZC Glyph dimers and their corresponding DZP and AC tautomers should be present in higher concentration than phosphonate zwitterionic Glyph monomers for high Glyph concentration, a fact that seems controversial in the literature.
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Affiliation(s)
- Sondes Meddeb-Limem
- Unité de recherche de Modélisation en Sciences Fondamentales et Didactiques, équipe de Chimie Théorique et Réactivité UR14ES10, Institut Préparatoire aux études d'Ingénieurs d'El Manar, Université de Tunis El Manar B. P. 244 El Manar II 2092 Tunis Tunisia +216 72 593 450 +216 72 593 450 + 216 54744256
| | - Arij Ben Fredj
- Unité de recherche de Modélisation en Sciences Fondamentales et Didactiques, équipe de Chimie Théorique et Réactivité UR14ES10, Institut Préparatoire aux études d'Ingénieurs d'El Manar, Université de Tunis El Manar B. P. 244 El Manar II 2092 Tunis Tunisia +216 72 593 450 +216 72 593 450 + 216 54744256
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3
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Multiple-H-bonded-zwitterionic tetramer structure for L-(+)-2-chlorophenylglycine, as investigated by UV, IR and Raman spectroscopy and electronic structure calculations. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.131218] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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4
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Srivastava R. Chemical reactivity and binding interactions in ribonucleic acid-peptide complexes. Proteins 2021; 90:765-775. [PMID: 34714954 DOI: 10.1002/prot.26272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 11/09/2022]
Abstract
The covalent and noncovalent backbone binding interactions in RNA-peptide complexes were studied by DFT methods. Four RNA structures R1(GGCUAGCC), R2(AAUCGAUU), R3(GGGAUCCC), and R4(AAAGCUUU) has been selected for eight protonated peptides (DR, ER, GR, KR, NGR, RR, tmeGnd (tme), and VR) interactions based on an experimental study (Anal Chem. 2019; 91:1659-1664). Chemical reactivity theory is used to study the reactivity of eight peptides with global descriptors. Lower hardness values reflected low stability and high reactivity for the protonated peptides. DR, ER, GR, KR, NGR, RR, and VR show lower value of ω, μ while tme has high value of ω, μ. Larger highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap for ER, GR, and KR showed greater structural stability for peptides. AutoDock and PatchDock results indicated that R1, R2, and R4 retain hairpin structures while interacting with peptide complexes. The calculated binding energies of (R1-R4)-peptide complexes from AutoDock tools are (1.49-11.12) kcal/mol. Results showed that the noncovalent interactions are stronger than the covalent interactions for R1-peptide complexes. The reason might be the transfer of proton from protonated ligand to deprotonated RNA, which has initiated the loss of the ligand. Also it has been observed that proton transfer has become energetically unfavorable in presence of additional hydrogen bonds which is predicted in the experimental results.
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Affiliation(s)
- Ruby Srivastava
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
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5
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Medina FE, Prejanò M. Water Molecules Allow the Intramolecular Activation of the Thiamine Di-Phosphate Cofactor in Human Transketolase: Mechanistic Insights into a Famous Proposal. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05414] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Fabiola E. Medina
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Autopista Concepción-Talcahuano, Talcahuano 7100, Chile
| | - Mario Prejanò
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-10691, Sweden
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6
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XRD structure and vibrational analysis of DL-β-Leucine, as aided by DFT tetramer model and characterized by NBO, AIM and NCI calculations. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128495] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Narayanan J, Hernández JG, Aguilar CAH, Rodríguez MM, Cerda SDG. Glutamine chelation governs the selective inhibition of Staphylococcus aureus and Salmonella typhi growth by cis-dichloro-bis(8-quinolinolato)zirconium(IV): Theory and experiment. Eur J Pharm Sci 2020; 151:105427. [PMID: 32544422 DOI: 10.1016/j.ejps.2020.105427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/25/2020] [Accepted: 06/11/2020] [Indexed: 10/24/2022]
Abstract
Quinolone-based Schiff base zirconium(IV) complex was studied as potential bacterial inhibitor against Gram-positive Staphylococcus aureus and Gram-negative Salmonella typhi growth, showing that the interaction of the complex with L-glutamine which presents in the membrane of wall leads cell death, and the mode of bacterial interaction was analyzed theoretically by DFT. Furthermore, the interaction of different amino acid residues L-alanine, D-alanine, L-lysine and D-glutamine with the metal complex through UV-vis docking studies was conducted observing that D-glutamine interacts efficiently among other amino acid residues. This observation is consistent with the interaction of the metal complex that was effective when participating in an insight of the peptidoglycan cell wall since the binding nature of glutamine potentially inhibits these microorganisms.
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Affiliation(s)
- Jayanthi Narayanan
- Division de Ingeniería en Nanotecnología, Universidad Politécnica del Valle de México, Av. Mexiquense s/n esquina Av. Universidad Politécnica, Tultitlan, Estado de México, CP 54910, México.
| | - José Guadalupe Hernández
- Centro Tecnológico, Facultad de Estudios Superiores (FES-Aragón), Universidad Nacional Autónoma de México (UNAM), Estado de México, CP 57130, México
| | - Carlos Alberto Huerta Aguilar
- Division de Ingeniería en Nanotecnología, Universidad Politécnica del Valle de México, Av. Mexiquense s/n esquina Av. Universidad Politécnica, Tultitlan, Estado de México, CP 54910, México
| | - Miguel Morales Rodríguez
- Division de Ingeniería en Nanotecnología, Universidad Politécnica del Valle de México, Av. Mexiquense s/n esquina Av. Universidad Politécnica, Tultitlan, Estado de México, CP 54910, México
| | - Susana Dianey Gallegos Cerda
- Division de Ingeniería en Nanotecnología, Universidad Politécnica del Valle de México, Av. Mexiquense s/n esquina Av. Universidad Politécnica, Tultitlan, Estado de México, CP 54910, México
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8
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Walhout EQ, Dorn SE, Martens J, Berden G, Oomens J, Cheong PHY, Kroll JH, O'Brien RE. Infrared Ion Spectroscopy of Environmental Organic Mixtures: Probing the Composition of α-Pinene Secondary Organic Aerosol. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:7604-7612. [PMID: 31184875 DOI: 10.1021/acs.est.9b02077] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Characterizing the chemical composition of organic aerosols can elucidate aging mechanisms as well as the chemical and physical properties of the aerosol. However, the high chemical complexity and often low atmospheric abundance present a difficult analytical challenge. Milligrams or more of material may be needed for speciated spectroscopic analysis. In contrast, mass spectrometry provides a very sensitive platform but limited structural information. Here, we combine the strengths of mass spectrometry and infrared (IR) action spectroscopy to generate characteristic IR spectra of individual, mass-isolated ion populations. Soft ionization combined with in situ infrared ion spectroscopy, using the tunable free-electron laser FELIX, provides detailed information on molecular structures and functional groups. We apply this technique, along with quantum mechanical modeling, to characterize organic molecules in secondary organic aerosol (SOA) formed from the ozonolysis of α-pinene. Spectral overlap with a standard is used to identify cis-pinonic acid. We also demonstrate the characterization of isomers for multiple SOA products using both quantum mechanical computations and analyses of fragment ion spectra. These results demonstrate the detailed structural information on isolated ions obtained by combining mass spectrometry with fingerprint IR spectroscopy.
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Affiliation(s)
- Emma Q Walhout
- Department of Chemistry , College of William and Mary , Williamsburg , Virginia 23185 , United States
| | - Shelby E Dorn
- Department of Chemistry , Oregon State University , 153 Gilbert Hall , Corvallis , Oregon 97331-4003 , United States
| | - Jonathan Martens
- Radboud University , Institute for Molecules and Materials, FELIX Laboratory , Toernooiveld 7c , 6525ED Nijmegen , The Netherlands
| | - Giel Berden
- Radboud University , Institute for Molecules and Materials, FELIX Laboratory , Toernooiveld 7c , 6525ED Nijmegen , The Netherlands
| | - Jos Oomens
- Radboud University , Institute for Molecules and Materials, FELIX Laboratory , Toernooiveld 7c , 6525ED Nijmegen , The Netherlands
- van't Hoff Institute for Molecular Sciences , University of Amsterdam , 1098XH Amsterdam , Science Park 908 , The Netherlands
| | - Paul H-Y Cheong
- Department of Chemistry , Oregon State University , 153 Gilbert Hall , Corvallis , Oregon 97331-4003 , United States
| | - Jesse H Kroll
- Department of Civil and Environmental Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Rachel E O'Brien
- Department of Chemistry , College of William and Mary , Williamsburg , Virginia 23185 , United States
- Department of Civil and Environmental Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
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9
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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.
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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
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10
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Long X, He L, Zhang Y, Ge M. Trimethyl borate-treated polytetrafluoroethylene micropowders with improved hydrophilic and adhesive properties based on coordination bond theory. SURF INTERFACE ANAL 2018. [DOI: 10.1002/sia.6390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- XiaoYun Long
- Key Laboratory of Eco-textiles; Ministry of Education, Jiangnan University; Wuxi 214412 China
- Jiangsu Broad New Textile Unite Development Co., Ltd; Nanjing 210039 China
| | - LiFen He
- Nanjing Jinhua Environmental Protection Science and Technology Co., Ltd; Nanjing 210039 China
| | - Yan Zhang
- Jiangsu Broad New Textile Unite Development Co., Ltd; Nanjing 210039 China
| | - Mingqiao Ge
- Key Laboratory of Eco-textiles; Ministry of Education, Jiangnan University; Wuxi 214412 China
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Heiles S, Berden G, Oomens J, Williams ER. Competition between salt bridge and non-zwitterionic structures in deprotonated amino acid dimers. Phys Chem Chem Phys 2018; 20:15641-15652. [DOI: 10.1039/c8cp01458b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The effect of side chain functional groups on salt bridge structures in deprotonated amino acid homodimers is investigated using both infrared multiple photon dissociation spectroscopy between 650 and 1850 cm−1 and theory.
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Affiliation(s)
- Sven Heiles
- Department of Chemistry
- University of California
- Berkeley
- USA
- Institute of Inorganic and Analytical Chemistry
| | - Giel Berden
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
| | - Jos Oomens
- Radboud University
- Institute for Molecules and Materials
- FELIX Laboratory
- 6525 ED Nijmegen
- The Netherlands
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12
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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.
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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
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13
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Loo RRO, Loo JA. Salt Bridge Rearrangement (SaBRe) Explains the Dissociation Behavior of Noncovalent Complexes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:975-90. [PMID: 27052739 PMCID: PMC4865452 DOI: 10.1007/s13361-016-1375-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 02/28/2016] [Accepted: 03/01/2016] [Indexed: 05/11/2023]
Abstract
Native electrospray ionization-mass spectrometry, with gas-phase activation and solution compositions that partially release subcomplexes, can elucidate topologies of macromolecular assemblies. That so much complexity can be preserved in gas-phase assemblies is remarkable, although a long-standing conundrum has been the differences between their gas- and solution-phase decompositions. Collision-induced dissociation of multimeric noncovalent complexes typically distributes products asymmetrically (i.e., by ejecting a single subunit bearing a large percentage of the excess charge). That unexpected behavior has been rationalized as one subunit "unfolding" to depart with more charge. We present an alternative explanation based on heterolytic ion-pair scission and rearrangement, a mechanism that inherently partitions charge asymmetrically. Excessive barriers to dissociation are circumvented in this manner, when local charge rearrangements access a lower-barrier surface. An implication of this ion pair consideration is that stability differences between high- and low-charge state ions usually attributed to Coulomb repulsion may, alternatively, be conveyed by attractive forces from ion pairs (salt bridges) stabilizing low-charge state ions. Should the number of ion pairs be roughly inversely related to charge, symmetric dissociations would be favored from highly charged complexes, as observed. Correlations between a gas-phase protein's size and charge reflect the quantity of restraining ion pairs. Collisionally-facilitated salt bridge rearrangement (SaBRe) may explain unusual size "contractions" seen for some activated, low charge state complexes. That some low-charged multimers preferentially cleave covalent bonds or shed small ions to disrupting noncovalent associations is also explained by greater ion pairing in low charge state complexes. Graphical Abstract ᅟ.
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Affiliation(s)
- Rachel R Ogorzalek Loo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA, 90095, USA.
| | - Joseph A Loo
- Department of Biological Chemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, CA, 90095, USA.
- UCLA/DOE Institute for Genomics and Proteomics, University of California-Los Angeles, Los Angeles, CA, 90095, USA.
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, CA, 90095, USA.
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14
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Schennach M, Schneeberger EM, Breuker K. Unfolding and Folding of the Three-Helix Bundle Protein KIX in the Absence of Solvent. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1079-88. [PMID: 26936183 PMCID: PMC4863917 DOI: 10.1007/s13361-016-1363-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 05/11/2023]
Abstract
Electron capture dissociation was used to probe the structure, unfolding, and folding of KIX ions in the gas phase. At energies for vibrational activation that were sufficiently high to cause loss of small molecules such as NH3 and H2O by breaking of covalent bonds in about 5% of the KIX (M + nH)(n+) ions with n = 7-9, only partial unfolding was observed, consistent with our previous hypothesis that salt bridges play an important role in stabilizing the native solution fold after transfer into the gas phase. Folding of the partially unfolded ions on a timescale of up to 10 s was observed only for (M + nH)(n+) ions with n = 9, but not n = 7 and n = 8, which we attribute to differences in the distribution of charges within the (M + nH)(n+) ions. Graphical Abstract ᅟ.
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Affiliation(s)
- Moritz Schennach
- Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innrain 80/82, 6020, Innsbruck, Austria
| | - Eva-Maria Schneeberger
- 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.
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