1
|
Krutilin A, Epp SW, Alejo GML, Busse F, Gitaric D, Schikora H, Schwoerer H, Tellkamp F. Peptide Mass Spectra from Micrometer-Thick Ice Films Produced with Femtosecond Pulses. Anal Chem 2022; 94:13359-13367. [PMID: 36153751 PMCID: PMC9535622 DOI: 10.1021/acs.analchem.2c01810] [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] [Indexed: 11/30/2022]
Abstract
![]()
We present a cryogenic
mass spectrometry protocol with the capability
to detect peptides in the attomole dilution range from ice films.
Our approach employs femtosecond laser pulses and implements neither
substrate modification nor proton donor agents in the aqueous solution,
known to facilitate analyte detection in mass spectrometry. In a systematic
study, we investigated the impact of temperature, substrate composition,
and irradiation wavelength (513 and 1026 nm) on the bradykinin signal
onset. Our findings show that substrate choice and irradiation wavelength
have a minor impact on signal intensity once the preparation protocol
is optimized. However, if the temperature is increased from −140
to 0 °C, which is accompanied by ice film thinning, a somehow
complex picture of analyte desorption and ionization is recognizable,
which has not been described in the literature yet. Under cryogenic
conditions (−140 °C), obtaining a signal is only possible
from isolated sweet spots across the film. If the thin ice film is
between −100 and −70 °C of temperature, these sweet
spots appear more frequently. Ice sublimation triggered by temperatures
above −70 °C leads to an intense and robust signal onset
that could be maintained for several hours. In addition to the above
findings, we notice that a vibrant fragmentation pattern produced
is strikingly similar with both wavelengths. Our findings suggest
that while following an optimized protocol, femtosecond mass spectrometry
has excellent potential to analyze small organic molecules and peptides
with a mass range of up to 2.5 kDa in aqueous solution without any
matrix, as employed in matrix-assisted laser desorption/ionization
(MALDI) or any substrate surface modification, found in surface-assisted
laser desorption/ionization (SALDI).
Collapse
Affiliation(s)
- Andrey Krutilin
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Sascha W Epp
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Glaynel M L Alejo
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Frederik Busse
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Djordje Gitaric
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Hendrik Schikora
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Heinrich Schwoerer
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Friedjof Tellkamp
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, Hamburg 22761, Germany
| |
Collapse
|
2
|
Meißner R, Feketeová L, Bayer A, Postler J, Limão‐Vieira P, Denifl S. Positive and negative ions of the amino acid histidine formed in low-energy electron collisions. JOURNAL OF MASS SPECTROMETRY : JMS 2019; 54:802-816. [PMID: 31410948 PMCID: PMC6916310 DOI: 10.1002/jms.4427] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 07/29/2019] [Accepted: 08/05/2019] [Indexed: 05/28/2023]
Abstract
Histidine is an aromatic amino acid crucial for the biological functioning of proteins and enzymes. When biological matter is exposed to ionising radiation, highly energetic particles interact with the surrounding tissue which leads to efficient formation of low-energy electrons. In the present study, the interaction of low-energy electrons with gas-phase histidine is studied at a molecular level in order to extend the knowledge of electron-induced reactions with amino acids. We report both on the formation of positive ions formed by electron ionisation and negative ions induced by electron attachment. The experimental data were complemented by quantum chemical calculations. Specifically, the free energies for possible fragmentation reactions were derived for the τ and the π tautomer of histidine to get insight into the structures of the formed ions and the corresponding neutrals. We report the experimental ionisation energy of (8.48 ± 0.03) eV for histidine which is in good agreement with the calculated vertical ionisation energy. In the case of negative ions, the dehydrogenated parent anion is the anion with the highest mass observed upon dissociative electron attachment. The comparison of experimental and computational results was also performed in view of a possible thermal decomposition of histidine during the experiments, since the sample was sublimated in the experiment by resistive heating of an oven. Overall, the present study demonstrates the effects of electrons as secondary particles in the chemical degradation of histidine. The reactions induced by those electrons differ when comparing positive and negative ion formation. While for negative ions, simple bond cleav ages prevail, the observed fragment cations exhibit partly restructuring of the molecule during the dissociation process.
Collapse
Affiliation(s)
- Rebecca Meißner
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI)Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of PhysicsUniversidade NOVA de Lisboa2829‐516CaparicaPortugal
| | - Linda Feketeová
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI)Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
- Institut de Physique Nucléaire de Lyon; CNRS/IN2P3, UMR5822Université de Lyon, Université Claude Bernard Lyon 143 Bd du 11 novembre 191869622VilleurbanneFrance
| | - Andreas Bayer
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI)Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Johannes Postler
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI)Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| | - Paulo Limão‐Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of PhysicsUniversidade NOVA de Lisboa2829‐516CaparicaPortugal
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences Innsbruck (CMBI)Universität InnsbruckTechnikerstraße 256020InnsbruckAustria
| |
Collapse
|
3
|
Shirota T, Tsuge M, Hikosaka Y, Soejima K, Hoshina K. Detection of Neutral Species in the MALDI Plume Using Femtosecond Laser Ionization: Quantitative Analysis of MALDI-MS Signals Based on a Semiequilibrium Proton Transfer Model. J Phys Chem A 2016; 121:31-39. [PMID: 27935303 DOI: 10.1021/acs.jpca.6b09591] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We investigated neutral species in the matrix-assisted laser desorption and ionization (MALDI) plume using femtosecond laser ionization spectrometry with simultaneous measurement of the standard MALDI spectrum of the identical MALDI event induced by pulsed UV laser irradiation. The ratio of neutral species in the plume [A]p/[M]p (A = phenylalanine (Phe) or alanine (Ala), M = 2,5-dihydroxybenzoic acid (DHB)) was confirmed to be the same as that of the sample mixture in the range of [A]0/[M]0 = 4 × 10-4-1, indicating the validity of the widely adopted approximation [A]p/[M]p = [A]0/[M]0 in the reaction quotient of the proton transfer reaction MH+ + A ⇄ M + AH+. An effective parameter representing the extent of thermal equilibrium in the thermal proton transfer model is introduced for the first time. Numerical simulation based on this semiequilibrium model successfully reproduced variations of MALDI signal intensities AH+ and MH+ with two parameters: the fraction of ionized matrix a ≤ 10-5 and an effective temperature T = 1200 and 1100 K for Phe/DHB and Ala/DHB systems, respectively. These values show good agreement with those determined previously by different experimental approaches. The extent of thermal equilibrium was determined to be 95% and 98% for Phe/DHB and Ala/DHB systems, respectively, suggesting that the proton transfer reactions almost proceed to their thermal equilibrium.
Collapse
Affiliation(s)
- Tatsuro Shirota
- Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences , 265-1, Higashijima, Akiha-ku, Niigata 956-8603, Japan
| | - Masashi Tsuge
- Department of Applied Chemistry, National Chiao Tung University , 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
| | - Yasumasa Hikosaka
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama , 2630 Sugitani, Toyama 930-0194, Japan
| | | | - Kennosuke Hoshina
- Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences , 265-1, Higashijima, Akiha-ku, Niigata 956-8603, Japan
| |
Collapse
|
4
|
Fanood MMR, Ram NB, Lehmann CS, Powis I, Janssen MHM. Enantiomer-specific analysis of multi-component mixtures by correlated electron imaging-ion mass spectrometry. Nat Commun 2015; 6:7511. [PMID: 26104140 PMCID: PMC4491818 DOI: 10.1038/ncomms8511] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 05/14/2015] [Indexed: 11/09/2022] Open
Abstract
Simultaneous, enantiomer-specific identification of chiral molecules in multi-component mixtures is extremely challenging. Many established techniques for single-component analysis fail to provide selectivity in multi-component mixtures and lack sensitivity for dilute samples. Here we show how enantiomers may be differentiated by mass-selected photoelectron circular dichroism using an electron-ion coincidence imaging spectrometer. As proof of concept, vapours containing ∼1% of two chiral monoterpene molecules, limonene and camphor, are irradiated by a circularly polarized femtosecond laser, resulting in multiphoton near-threshold ionization with little molecular fragmentation. Large chiral asymmetries (2-4%) are observed in the mass-tagged photoelectron angular distributions. These asymmetries switch sign according to the handedness (R- or S-) of the enantiomer in the mixture and scale with enantiomeric excess of a component. The results demonstrate that mass spectrometric identification of mixtures of chiral molecules and quantitative determination of enantiomeric excess can be achieved in a table-top instrument.
Collapse
Affiliation(s)
- Mohammad M Rafiee Fanood
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| | - N Bhargava Ram
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| | - C Stefan Lehmann
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| | - Ivan Powis
- School of Chemistry, University Park, University of Nottingham, Nottingham NG7 2RD, UK
| | - Maurice H M Janssen
- LaserLaB Amsterdam and Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, Amsterdam 1081 HV, The Netherlands
| |
Collapse
|
5
|
Greenwood JB, Miles J, Camillis SD, Mulholland P, Zhang L, Parkes MA, Hailes HC, Fielding HH. Resonantly Enhanced Multiphoton Ionization Spectrum of the Neutral Green Fluorescent Protein Chromophore. J Phys Chem Lett 2014; 5:3588-3592. [PMID: 26278614 DOI: 10.1021/jz5019256] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The photophysics of the green fluorescent protein is governed by the electronic structure of the chromophore at the heart of its β-barrel protein structure. We present the first two-color, resonance-enhanced, multiphoton ionization spectrum of the isolated neutral chromophore in vacuo with supporting electronic structure calculations. We find the absorption maximum to be 3.65 ± 0.05 eV (340 ± 5 nm), which is blue-shifted by 0.5 eV (55 nm) from the absorption maximum of the protein in its neutral form. Our results show that interactions between the chromophore and the protein have a significant influence on the electronic structure of the neutral chromophore during photoabsorption and provide a benchmark for the rational design of novel chromophores as fluorescent markers or photomanipulators.
Collapse
Affiliation(s)
- Jason B Greenwood
- †Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, United Kingdom
| | - Jordan Miles
- †Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, United Kingdom
| | - Simone De Camillis
- †Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, United Kingdom
| | - Peter Mulholland
- †Centre for Plasma Physics, School of Maths and Physics, Queen's University Belfast, University Road, Belfast BT7 1NN, United Kingdom
| | - Lijuan Zhang
- ‡Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Michael A Parkes
- ‡Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Helen C Hailes
- ‡Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Helen H Fielding
- ‡Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| |
Collapse
|
6
|
Bull JN, Lee JWL, Gardiner SH, Vallance C. An introduction to velocity-map imaging mass spectrometry (VMImMS). EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2014; 20:117-129. [PMID: 24895772 DOI: 10.1255/ejms.1264] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This account introduces a new variant of time-of-flight mass spectrometry, termed velocity-map imaging mass spectrometry (VMImMS). While the ion abundances recorded in conventional ToF-MS measurements are highly useful for molecular quantification and structure determination, the final parent and fragment ion yields are Largely blind to the dynamics of the processes in which the ions were formed inside the mass spectrometer. By recording the velocity distribution of each ion in tandem with the mass spectrum, not only can the details of the dissociative ionisation dynamics be unravelled, but the extra dimensions of information can be used for enhanced molecular fingerprinting, separating contributions from ions with identical mass-to-charge ratio and resolving components within mixtures, to name but a few examples. Measuring ion-velocity distributions within a mass spectrometry measurement is not new, but incorporating imaging techniques developed within the reaction dynamics community provides vastly improved velocity resolution for all ions simultaneously in a single-stage instrument. This account provides an introduction to VMImMS, outlines the fundamental instrumentation and detector requirements and the challenges associated with developing the method further, and details proof-of-concept work from our Laboratory on a number of potential applications of the technique.
Collapse
|