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Hellwig N, Martin J, Morgner N. LILBID-MS: using lasers to shed light on biomolecular architectures. Biochem Soc Trans 2022; 50:1057-1067. [PMID: 35695670 PMCID: PMC9317959 DOI: 10.1042/bst20190881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 05/15/2022] [Accepted: 05/20/2022] [Indexed: 11/17/2022]
Abstract
Structural Biology has moved beyond the aim of simply identifying the components of a cellular subsystem towards analysing the dynamics and interactions of multiple players within a cell. This focal shift comes with additional requirements for the analytical tools used to investigate these systems of increased size and complexity, such as Native Mass Spectrometry, which has always been an important tool for structural biology. Scientific advance and recent developments, such as new ways to mimic a cell membrane for a membrane protein, have caused established methods to struggle to keep up with the increased demands. In this review, we summarize the possibilities, which Laser Induced Liquid Bead Ion Desorption (LILBID) mass spectrometry offers with regard to the challenges of modern structural biology, like increasingly complex sample composition, novel membrane mimics and advanced structural analysis, including next neighbor relations and the dynamics of complex formation.
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Affiliation(s)
- Nils Hellwig
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt/Main, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Janosch Martin
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt/Main, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Nina Morgner
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt/Main, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
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2
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Urban RD, Fischer TG, Charvat A, Wink K, Krafft B, Ohla S, Zeitler K, Abel B, Belder D. On-chip mass spectrometric analysis in non-polar solvents by liquid beam infrared matrix-assisted laser dispersion/ionization. Anal Bioanal Chem 2021; 413:1561-1570. [PMID: 33479818 PMCID: PMC7921053 DOI: 10.1007/s00216-020-03115-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/01/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022]
Abstract
By the on-chip integration of a droplet generator in front of an emitter tip, droplets of non-polar solvents are generated in a free jet of an aqueous matrix. When an IR laser irradiates this free liquid jet consisting of water as the continuous phase and the non-polar solvent as the dispersed droplet phase, the solutes in the droplets are ionized. This ionization at atmospheric pressure enables the mass spectrometric analysis of non-polar compounds with the aid of a surrounding aqueous matrix that absorbs IR light. This works both for non-polar solvents such as n-heptane and for water non-miscible solvents like chloroform. In a proof of concept study, this approach is applied to monitor a photooxidation of N-phenyl-1,2,3,4-tetrahydroisoquinoline. By using water as an infrared absorbing matrix, analytes, dissolved in non-polar solvents from reactions carried out on a microchip, can be desorbed and ionized for investigation by mass spectrometry.
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Affiliation(s)
- Raphael D Urban
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Tillmann G Fischer
- Institut für Organische Chemie, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany
| | - Ales Charvat
- Leibniz-Institut für Oberflächenmodifizierung e.V., Abteilung Funktionale Oberflächen, Permoserstr. 15, 04318, Leipzig, Germany
| | - Konstantin Wink
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Benjamin Krafft
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Stefan Ohla
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Kirsten Zeitler
- Institut für Organische Chemie, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany
| | - Bernd Abel
- Leibniz-Institut für Oberflächenmodifizierung e.V., Abteilung Funktionale Oberflächen, Permoserstr. 15, 04318, Leipzig, Germany
| | - Detlev Belder
- Institut für Analytische Chemie, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany.
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Prüfert C, Urban RD, Fischer TG, Villatoro J, Riebe D, Beitz T, Belder D, Zeitler K, Löhmannsröben HG. In situ monitoring of photocatalyzed isomerization reactions on a microchip flow reactor by IR-MALDI ion mobility spectrometry. Anal Bioanal Chem 2020; 412:7899-7911. [PMID: 32918557 PMCID: PMC7550389 DOI: 10.1007/s00216-020-02923-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/17/2020] [Accepted: 08/27/2020] [Indexed: 01/21/2023]
Abstract
The visible-light photocatalytic E/Z isomerization of olefins can be mediated by a wide spectrum of triplet sensitizers (photocatalysts). However, the search for the most efficient photocatalysts through screenings in photo batch reactors is material and time consuming. Capillary and microchip flow reactors can accelerate this screening process. Combined with a fast analytical technique for isomer differentiation, these reactors can enable high-throughput analyses. Ion mobility (IM) spectrometry is a cost-effective technique that allows simple isomer separation and detection on the millisecond timescale. This work introduces a hyphenation method consisting of a microchip reactor and an infrared matrix-assisted laser desorption ionization (IR-MALDI) ion mobility spectrometer that has the potential for high-throughput analysis. The photocatalyzed E/Z isomerization of ethyl-3-(pyridine-3-yl)but-2-enoate (E-1) as a model substrate was chosen to demonstrate the capability of this device. Classic organic triplet sensitizers as well as Ru-, Ir-, and Cu-based complexes were tested as catalysts. The ionization efficiency of the Z-isomer is much higher at atmospheric pressure which is due to a higher proton affinity. In order to suppress proton transfer reactions by limiting the number of collisions, an IM spectrometer working at reduced pressure (max. 100 mbar) was employed. This design reduced charge transfer reactions and allowed the quantitative determination of the reaction yield in real time. Among 14 catalysts tested, four catalysts could be determined as efficient sensitizers for the E/Z isomerization of ethyl cinnamate derivative E-1. Conversion rates of up to 80% were achieved in irradiation time sequences of 10 up to 180 s. With respect to current studies found in the literature, this reduces the acquisition times from several hours to only a few minutes per scan.
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Affiliation(s)
- Chris Prüfert
- University of Potsdam, Physical Chemistry, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
| | - Raphael David Urban
- Institute of Analytical Chemistry, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Tillmann Georg Fischer
- Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany
| | - José Villatoro
- University of Potsdam, Physical Chemistry, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Daniel Riebe
- University of Potsdam, Physical Chemistry, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Toralf Beitz
- University of Potsdam, Physical Chemistry, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Detlev Belder
- Institute of Analytical Chemistry, Leipzig University, Linnéstraße 3, 04103, Leipzig, Germany
| | - Kirsten Zeitler
- Institute of Organic Chemistry, Leipzig University, Johannisallee 29, 04103, Leipzig, Germany
| | - Hans-Gerd Löhmannsröben
- University of Potsdam, Physical Chemistry, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
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Curti C, Battistini L, Sartori A, Zanardi F. New Developments of the Principle of Vinylogy as Applied to π-Extended Enolate-Type Donor Systems. Chem Rev 2020; 120:2448-2612. [PMID: 32040305 PMCID: PMC7993750 DOI: 10.1021/acs.chemrev.9b00481] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Indexed: 12/19/2022]
Abstract
The principle of vinylogy states that the electronic effects of a functional group in a molecule are possibly transmitted to a distal position through interposed conjugated multiple bonds. As an emblematic case, the nucleophilic character of a π-extended enolate-type chain system may be relayed from the legitimate α-site to the vinylogous γ, ε, ..., ω remote carbon sites along the chain, provided that suitable HOMO-raising strategies are adopted to transform the unsaturated pronucleophilic precursors into the reactive polyenolate species. On the other hand, when "unnatural" carbonyl ipso-sites are activated as nucleophiles (umpolung), vinylogation extends the nucleophilic character to "unnatural" β, δ, ... remote sites. Merging the principle of vinylogy with activation modalities and concepts such as iminium ion/enamine organocatalysis, NHC-organocatalysis, cooperative organo/metal catalysis, bifunctional organocatalysis, dicyanoalkylidene activation, and organocascade reactions represents an impressive step forward for all vinylogous transformations. This review article celebrates this evolutionary progress, by collecting, comparing, and critically describing the achievements made over the nine year period 2010-2018, in the generation of vinylogous enolate-type donor substrates and their use in chemical synthesis.
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Affiliation(s)
| | | | | | - Franca Zanardi
- Dipartimento di Scienze degli
Alimenti e del Farmaco, Università
di Parma, Parco Area delle Scienze 27A, 43124 Parma, Italy
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Affiliation(s)
- Iulia M. Lazar
- Department of Biological Sciences, Academy of Integrated Sciences, Virginia Tech, Blacksburg, Virginia 24061, United States
- Carilion School of Medicine, Academy of Integrated Sciences, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Nicholas S. Gulakowski
- Systems Biology, Academy of Integrated Sciences, Virginia Tech, Blacksburg, Virginia 24061, United States
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Sheathless coupling of microchip electrophoresis to ESI-MS utilising an integrated photo polymerised membrane for electric contacting. Anal Bioanal Chem 2018; 410:5741-5750. [PMID: 29974150 DOI: 10.1007/s00216-018-1226-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/12/2018] [Accepted: 06/22/2018] [Indexed: 10/28/2022]
Abstract
In this article, we present a novel approach for the sheathless coupling of microchip electrophoresis (MCE) with electrospray mass spectrometry (ESI-MS). The key element is an ion-conductive hydrogel membrane, placed between the separation channel and an adjacent microfluidic supporting channel, contacted via platinum electrodes. This solves the persistent challenge in hyphenation of mass spectrometry to chip electrophoresis, to ensure a reliable electrical connection at the end of the electrophoresis channel without sacrificing separation performance and sensitivity. Stable electric contacting is achieved via a Y-shaped supporting channel structure, separated from the main channel by a photo polymerised, ion permeable hydrogel membrane. Thus, the potential gradient required for performing electrophoretic separations can be generated while simultaneously preventing gas formation due to electrolysis. In contrast to conventional make-up or sheathflow approaches, sample dilution is also avoided. Rapid prototyping allowed the study of different chip-based approaches, i.e. sheathless, open sheathflow and electrode support channel designs, for coupling MCE to ESI-MS. The performance was evaluated with fluorescence microscopy and mass spectrometric detection. The obtained results revealed that the detection sensitivity obtained in such Y-channel chips with integrated hydrogel membranes was superior because sample dilution or loss was prevented. Furthermore, band broadening is reduced compared to similar open structures without a membrane.
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Appun J, Stolz F, Naumov S, Abel B, Schneider C. Modular Synthesis of Dipyrroloquinolines: A Combined Synthetic and Mechanistic Study. J Org Chem 2018; 83:1737-1744. [PMID: 29355317 DOI: 10.1021/acs.joc.7b02466] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A straightforward synthesis of [1,2-a][3',2'-c]dipyrroloquinolines has been developed generating up to eight new σ-bonds and five new stereogenic centers in a simple and modular one-pot operation. Generally good to excellent yields and moderate to good stereoselectivities in favor of the all-cis stereoisomer were observed. A detailed investigation combining synthetic studies, analytical measurements, and theoretical calculations has been conducted to elucidate the reaction mechanism using ESI- and liquid-beam IR-laser desorption mass spectrometry as well as DFT calculations. Key steps of this sequential transformation include a Lewis acid-catalyzed vinylogous Mukaiyama-Mannich reaction of bis(silyl) dienediolate 1 and a Brønsted acid-promoted Mannich-Pictet-Spengler reaction cascade reaction to complete the synthesis of the dipyrroloquinoline core of the target compounds.
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Affiliation(s)
- Johannes Appun
- Institute of Organic Chemistry, University of Leipzig , Johannisallee 29, D-04103 Leipzig, Germany
| | - Ferdinand Stolz
- Leibniz-Institute of Surface Modification (IOM) , Permoserstrasse 15, D-04318 Leipzig, Germany.,Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University of Leipzig , Linnéstrasse 3, D-04103 Leipzig, Germany
| | - Sergej Naumov
- Leibniz-Institute of Surface Modification (IOM) , Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Bernd Abel
- Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, University of Leipzig , Linnéstrasse 3, D-04103 Leipzig, Germany
| | - Christoph Schneider
- Institute of Organic Chemistry, University of Leipzig , Johannisallee 29, D-04103 Leipzig, Germany
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