1
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Talbot FO, Suarez CM, Nagy AM, Chen JC, Djavani-Tabrizi I, Clotea I, Jockusch RA. Robust Fluorescence Collection Module for Wide-Bore Ion Cyclotron Resonance Mass Spectrometers. Anal Chem 2023; 95:17193-17202. [PMID: 37963234 DOI: 10.1021/acs.analchem.3c01801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Mass spectrometers are at the heart of the most powerful toolboxes available to scientists when studying molecular structure, conformation, and dynamics in controlled molecular environments. Improved molecular characterization brought about by the implementation of new orthogonal methods into mass spectrometry-enabled analyses opens deeper insight into the complex interplay of forces that underlie chemistry. Here, we detail how one can add fluorescence detection to commercial ultrahigh-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers without adverse effects to its preexisting analytical tools. This advance enables measurements based on fluorescence detection, such as Förster resonance energy transfer (FRET), to be used in conjunction with other MS/MS techniques to probe the conformation and dynamics of large biomolecules, such as proteins and their complexes, in the highly controlled environment of a Penning trap.
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Affiliation(s)
- Francis O Talbot
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Cynthia M Suarez
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Andrea M Nagy
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - JoAnn C Chen
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Iden Djavani-Tabrizi
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Ioana Clotea
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Rebecca A Jockusch
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
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2
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Diop M, El-Hayek M, Attard J, Muhieddine A, Veremeienko V, Soorkia S, Carbonnière P, de la Lande A, Soep B, Shafizadeh N. Chlorophyll and pheophytin protonated and deprotonated ions: Observation and theory. J Chem Phys 2023; 159:194308. [PMID: 37987519 DOI: 10.1063/5.0174351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 10/30/2023] [Indexed: 11/22/2023] Open
Abstract
Pheophytin a and chlorophyll a have been investigated by electrospray mass spectrometry in the positive and negative modes, in view of the importance of the knowledge of their properties in photosynthesis. Pheophytin and chlorophyll are both observed intensely in the protonated mode, and their main fragmentation route is the loss of their phytyl chain. Pheophytin is observed intact in the negative mode, while under collisions, it is primarily cleaved beyond the phytyl chain and loses the attaching propionate group. Chlorophyll is not detected in normal conditions in the negative mode, but addition of methanol solvent molecule is detected. Fragmentation of this adduct primarily forms a product (-30 amu) that dissociates into dephytyllated deprotonated chlorophyll. Semi-empirical molecular dynamics calculations show that the phytyl chain is unfolded from the chlorin cycle in pheophytin a and folded in chlorophyll a. Density functional theory calculations have been conducted to locate the charges on protonated and deprotonated pheophytin a and chlorophyll a and have found the major location sites that are notably more stable in energy by more than 0.5 eV than the others. The deprotonation site is found identical for pheophytin a and the chlorophyll a-methanol adduct. This is in line with experiment and calculation locating the addition of methanol on a double bond of deprotonated chlorophyll a.
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Affiliation(s)
- M Diop
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - M El-Hayek
- Université Paris Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
| | - J Attard
- Université Paris Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
- Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Pau, France
| | - A Muhieddine
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - V Veremeienko
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - S Soorkia
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - Ph Carbonnière
- Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Pau, France
| | - A de la Lande
- Université Paris Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France
| | - B Soep
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
| | - N Shafizadeh
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d' Orsay, 91405 Orsay, France
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3
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Irshadeen IM, Walden SL, Wegener M, Truong VX, Frisch H, Blinco JP, Barner-Kowollik C. Action Plots in Action: In-Depth Insights into Photochemical Reactivity. J Am Chem Soc 2021; 143:21113-21126. [PMID: 34859671 DOI: 10.1021/jacs.1c09419] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Predicting wavelength-dependent photochemical reactivity is challenging. Herein, we revive the well-established tool of measuring action spectra and adapt the technique to map wavelength-resolved covalent bond formation and cleavage in what we term "photochemical action plots". Underpinned by tunable lasers, which allow excitation of molecules with near-perfect wavelength precision, the photoinduced reactivity of several reaction classes have been mapped in detail. These include photoinduced cycloadditions and bond formation based on photochemically generated o-quinodimethanes and 1,3-dipoles such as nitrile imines as well as radical photoinitiator cleavage. Organized by reaction class, these data demonstrate that UV/vis spectra fail to act as a predictor for photochemical reactivity at a given wavelength in most of the examined reactions, with the photochemical reactivity being strongly red shifted in comparison to the absorption spectrum. We provide an encompassing perspective of the power of photochemical action plots for bond-forming reactions and their emerging applications in the design of wavelength-selective photoresists and photoresponsive soft-matter materials.
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Affiliation(s)
- Ishrath Mohamed Irshadeen
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.,Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia
| | - Sarah L Walden
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.,Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia
| | - Martin Wegener
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Vinh X Truong
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.,Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia
| | - Hendrik Frisch
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.,Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia
| | - James P Blinco
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.,Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia
| | - Christopher Barner-Kowollik
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.,Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, Queensland 4000, Australia.,Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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4
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Gruber E, Teiwes R, Kjær C, Brøndsted Nielsen S, Andersen LH. Tuning fast excited-state decay by ligand attachment in isolated chlorophyll a. Phys Chem Chem Phys 2021; 24:149-155. [PMID: 34901981 DOI: 10.1039/d1cp04356k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Excited-state dynamics plays a key role for light harvesting and energy transport in photosynthetic proteins but it is nontrivial to separate the intrinsic photophysics of the light-absorbers (chlorophylls) from interactions with the protein matrix. Here we study chlorophyll a (4-coordinate complex) and axially ligated chlorophyll a (5-coordinate complex) isolated in vacuo applying mass spectrometry to shed light on the intrinsic dynamics in the absence of nearby chlorophylls, carotenoids, amino acids, and water molecules. The 4-coordinate complexes are tagged by quaternary ammonium ions while the charge is provided by a formate ligand in the case of 5-coordinate complexes. Regardless of excitation to the Soret band or the Q band, a fast ps decay is observed, which is ascribed to the decay of the lowest excited singlet state either by intersystem crossing (ISC) to nearby triplet states or by excited-state relaxation on the excited-state potential-energy surface. The lifetime of the first excited state is 15 ps with Mg2+ at the chlorophyll center, but only 1.7 ps when formate is attached to Mg2+. When the Soret band is excited, an initial sup-ps relaxation is observed which is ascribed to fast internal conversion to the first excited state. With respect to ISC, two factors seem to play a role for the reduced lifetime of the formate-chlorophyll complex: (i) The Mg ion is pulled out of the porphyrin plane thus reducing the symmetry of the chromophore, and (ii) the first excited state (Q band) and T3 are tuned almost into resonance by the ligand, which increases the singlet-triplet mixing.
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Affiliation(s)
- Elisabeth Gruber
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
| | - Ricky Teiwes
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
| | - Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
| | | | - Lars H Andersen
- Department of Physics and Astronomy, Aarhus University, Aarhus 8000C, Denmark.
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5
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Kjær C, Langeland J, Lindkvist TT, Sørensen ER, Stockett MH, Kjaergaard HG, Nielsen SB. A new setup for low-temperature gas-phase ion fluorescence spectroscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033105. [PMID: 33820085 DOI: 10.1063/5.0038880] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Here, we present a new instrument named LUNA2 (LUminescence iNstrument in Aarhus 2), which is purpose-built to measure dispersed fluorescence spectra of gaseous ions produced by electrospray ionization and cooled to low temperatures (<100 K). LUNA2 is, as an earlier room-temperature setup (LUNA), optimized for a high collection efficiency of photons and includes improvements based on our operational experience with LUNA. The fluorescence cell is a cylindrical Paul trap made of copper with a hole in the ring electrode to permit laser light to interact with the trapped ions, and one end-cap electrode is a mesh grid combined with an aspheric condenser lens. The entrance and exit electrodes are both in physical contact with the liquid-nitrogen cooling unit to reduce cooling times. Mass selection is done in a two-step scheme where, first, high-mass ions are ejected followed by low-mass ions according to the Mathieu stability region. This scheme may provide a higher mass resolution than when only one DC voltage is used. Ions are irradiated by visible light delivered from a nanosecond 20-Hz pulsed laser, and dispersed fluorescence is measured with a spectrometer combined with an iCCD camera that allows intensification of the signal for a short time interval. LUNA2 contains an additional Paul trap that can be used for mass selection before ions enter the fluorescence cell, which potentially is relevant to diminishing RF heating in the cold trap. Successful operation of the setup is demonstrated from experiments with rhodamine dyes and oxazine-4, and spectral changes with temperature are identified.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Jeppe Langeland
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | | | - Emma Rostal Sørensen
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Henrik G Kjaergaard
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
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6
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Cercola R, Wong NGK, Rhodes C, Olijnyk L, Mistry NS, Hall LM, Berenbeim JA, Lynam JM, Dessent CEH. A “one pot” mass spectrometry technique for characterizing solution- and gas-phase photochemical reactions by electrospray mass spectrometry. RSC Adv 2021; 11:19500-19507. [PMID: 35479237 PMCID: PMC9033567 DOI: 10.1039/d1ra02581c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/17/2021] [Indexed: 12/28/2022] Open
Abstract
The characterization of new photochemical pathways is important to progress the understanding of emerging areas of light-triggered inorganic and organic chemistry. In this context, the development of platforms to perform routine characterization of photochemical reactions remains an important goal for photochemists. Here, we demonstrate a new instrument that can be used to characterise both solution-phase and gas-phase photochemical reactions through electrospray ionisation mass spectrometry (ESI-MS). The gas-phase photochemistry is studied by novel laser-interfaced mass spectrometry (LIMS), where the molecular species of interest is introduced to the gas-phase by ESI, mass-selected and then subjected to laser photodissociation in the ion-trap. On-line solution-phase photochemistry is initiated by LEDs prior to ESI-MS in the same instrument with ESI-MS again being used to monitor photoproducts. Two ruthenium metal carbonyls, [Ru(η5-C5H5)(PPh3)2CO][PF6] and [Ru(η5-C5H5)(dppe)CO][PF6] (dppe = 1,2-bis(diphenylphosphino)ethane) are studied using this methodology. We show that the gas-phase photofragmentation pathways observed for the ruthenium complexes via LIMS (i.e. loss of CO + PPh3 ligands from [Ru(η5-C5H5)(PPh3)2CO]+ and loss of just CO from [Ru(η5-C5H5)(dppe)CO]+) mirror the solution-phase photochemistry at 3.4 eV. The advantages of performing the gas-phase and solution-phase photochemical characterisations in a single instrument are discussed. The solution and gas-phase dissociative photochemistry of two ruthenium half-sandwich complexes are analysed with electrospray ionisation mass spectrometry in a novel instrument.![]()
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Affiliation(s)
| | | | - Chris Rhodes
- Department of Chemistry
- University of York
- York YO10 5DD
- UK
| | - Lorna Olijnyk
- Department of Chemistry
- University of York
- York YO10 5DD
- UK
| | | | - Lewis M. Hall
- Department of Chemistry
- University of York
- York YO10 5DD
- UK
| | | | - Jason M. Lynam
- Department of Chemistry
- University of York
- York YO10 5DD
- UK
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7
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Furlan C, Berenbeim JA, Dessent CEH. Photoproducts of the Photodynamic Therapy Agent Verteporfin Identified via Laser Interfaced Mass Spectrometry. Molecules 2020; 25:molecules25225280. [PMID: 33198255 PMCID: PMC7696214 DOI: 10.3390/molecules25225280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/08/2020] [Accepted: 11/09/2020] [Indexed: 12/12/2022] Open
Abstract
Verteporfin, a free base benzoporphyrin derivative monoacid ring A, is a photosensitizing drug for photodynamic therapy (PDT) used in the treatment of the wet form of macular degeneration and activated by red light of 689 nm. Here, we present the first direct study of its photofragmentation channels in the gas phase, conducted using a laser interfaced mass spectrometer across a broad photoexcitation range from 250 to 790 nm. The photofragmentation channels are compared with the collision-induced dissociation (CID) products revealing similar dissociation pathways characterized by the loss of the carboxyl and ester groups. Complementary solution-phase photolysis experiments indicate that photobleaching occurs in verteporfin in acetonitrile; a notable conclusion, as photoinduced activity in Verteporfin was not thought to occur in homogenous solvent conditions. These results provide unique new information on the thermal break-down products and photoproducts of this light-triggered drug.
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8
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Sirohiwal A, Berraud-Pache R, Neese F, Izsák R, Pantazis DA. Accurate Computation of the Absorption Spectrum of Chlorophyll a with Pair Natural Orbital Coupled Cluster Methods. J Phys Chem B 2020; 124:8761-8771. [PMID: 32930590 PMCID: PMC7584356 DOI: 10.1021/acs.jpcb.0c05761] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
The
ability to accurately compute low-energy excited states of
chlorophylls is critically important for understanding the vital roles
they play in light harvesting, energy transfer, and photosynthetic
charge separation. The challenge for quantum chemical methods arises
both from the intrinsic complexity of the electronic structure problem
and, in the case of biological models, from the need to account for
protein–pigment interactions. In this work, we report electronic
structure calculations of unprecedented accuracy for the low-energy
excited states in the Q and B bands of chlorophyll a. This is achieved by using the newly developed domain-based local
pair natural orbital (DLPNO) implementation of the similarity transformed
equation of motion coupled cluster theory with single and double excitations
(STEOM-CCSD) in combination with sufficiently large and flexible basis
sets. The results of our DLPNO–STEOM-CCSD calculations are
compared with more approximate approaches. The results demonstrate
that, in contrast to time-dependent density functional theory, the
DLPNO–STEOM-CCSD method provides a balanced performance for
both absorption bands. In addition to vertical excitation energies,
we have calculated the vibronic spectrum for the Q and B bands through
a combination of DLPNO–STEOM-CCSD and ground-state density
functional theory frequency calculations. These results serve as a
basis for comparison with gas-phase experiments.
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Affiliation(s)
- Abhishek Sirohiwal
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.,Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Romain Berraud-Pache
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Róbert Izsák
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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9
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Kjær C, Gruber E, Nielsen SB, Andersen LH. Color tuning of chlorophyll a and b pigments revealed from gas-phase spectroscopy. Phys Chem Chem Phys 2020; 22:20331-20336. [PMID: 32895686 DOI: 10.1039/d0cp03210g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Chlorophyll (Chl) pigments are responsible for vital mechanisms in photosynthetic proteins: light harvesting, energy transfer and charge separation. A complex interplay between the Chl molecule and its microenvironment determines its transition energy. Interactions such as excitonic coupling with one or more pigments (Chls or carotenoids), axial ligation to the magnesium center, or electrostatic interactions between Chl and nearby amino-acid residues all influence the photophysical properties. Here we use time-resolved photodissociation action spectroscopy to determine transition energies of Chla/b complexes in vacuo to directly compare the impact of a negatively charged axial ligand (formate) to that of exciton coupling between two Chls. Experiments carried out at the electrostatic ion storage ring ELISA allow dissociation to be sampled on hundreds of milliseconds time scale. Absorption-band maxima of Chla-formate complexes are found at 433 ± 4 nm/2.86 ± 0.03 eV (Soret band) and in the region 654-675 nm/1.84-1.90 eV (Q band) and those of Chla dimers tagged by a quaternary ammonium ion at 419 ± 5 nm/2.96 ± 0.04 eV (Soret band) and 647 nm/1.92 eV (Q band). The axial ligand strongly affects the Chla transition energies causing redshifts of 0.21 eV of the Soret band and 0.04-0.1 eV of the Q band compared to Chla tagged by a quaternary ammonium. Slightly smaller shifts were found in case of Chlb. The redshifts are approximately twice that induced by excitonic coupling between two Chlas, also tagged by a quaternary ammonium ion. Axial ligation brings the absorption by isolated Chls very close to that of photosynthetic proteins.
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Affiliation(s)
- Christina Kjær
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | - Elisabeth Gruber
- Department of Physics and Astronomy, Aarhus University, Denmark.
| | | | - Lars H Andersen
- Department of Physics and Astronomy, Aarhus University, Denmark.
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10
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Gruber E, Kjaer C, Nielsen SB, Andersen LH. Intrinsic Photophysics of Light-harvesting Charge-tagged Chlorophyll a and b Pigments. Chemistry 2019; 25:9153-9158. [PMID: 31095797 DOI: 10.1002/chem.201901786] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 05/15/2019] [Indexed: 12/20/2022]
Abstract
Chlorophylls a and b (Chla/b) are responsible for light-harvesting by photosynthetic proteins in plants. They display broad absorption in the visible region with multiple bands, due to the asymmetry of the macrocycle and strong vibronic coupling. Their photophysics relies on the microenvironment, with regard to transition energies as well as quenching of triplet states. Here, we firmly establish the splitting of the Q and Soret bands into x- and y- polarized bands for the isolated molecules in vacuo, and resolve vibronic features. Storage-ring experiments reveal that dissociation of photoexcited charge-tagged complexes occurs over several milliseconds, but with two different time constants. A fast decay is ascribed to dissociation after internal conversion and a slow decay to the population of a triplet state that acts as a bottleneck. Support for the latter is provided by pump-probe experiments, where a second laser pulse probes the long-lived triplet state.
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Affiliation(s)
| | - Christina Kjaer
- Department of Physics and Astronomy, Aarhus University, Denmark
| | | | - Lars H Andersen
- Department of Physics and Astronomy, Aarhus University, Denmark
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11
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Giacomozzi L, Kjær C, Langeland Knudsen J, Andersen LH, Brøndsted Nielsen S, Stockett MH. Absorption and luminescence spectroscopy of mass-selected flavin adenine dinucleotide mono-anions. J Chem Phys 2018; 148:214309. [PMID: 29884035 DOI: 10.1063/1.5024028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We report the absorption profile of isolated Flavin Adenine Dinucleotide (FAD) mono-anions recorded using photo-induced dissociation action spectroscopy. In this charge state, one of the phosphoric acid groups is deprotonated and the chromophore itself is in its neutral oxidized state. These measurements cover the first four optical transitions of FAD with excitation energies from 2.3 to 6.0 eV (210-550 nm). The S0 → S2 transition is strongly blue shifted relative to aqueous solution, supporting the view that this transition has a significant charge-transfer character. The remaining bands are close to their solution-phase positions. This confirms that the large discrepancy between quantum chemical calculations of vertical transition energies and solution-phase band maxima cannot be explained by solvent effects. We also report the luminescence spectrum of FAD mono-anions in vacuo. The gas-phase Stokes shift for S1 is 3000 cm-1, which is considerably larger than any previously reported for other molecular ions and consistent with a significant displacement of the ground and excited state potential energy surfaces. Consideration of the vibronic structure is thus essential for simulating the absorption and luminescence spectra of flavins.
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Affiliation(s)
- L Giacomozzi
- Department of Physics, Stockholm University, Stockholm, Sweden
| | - C Kjær
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | | | - L H Andersen
- Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
| | | | - M H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden
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12
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Daly S, MacAleese L, Dugourd P, Chirot F. Combining Structural Probes in the Gas Phase - Ion Mobility-Resolved Action-FRET. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:133-139. [PMID: 29038996 DOI: 10.1007/s13361-017-1824-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/15/2017] [Accepted: 09/27/2017] [Indexed: 06/07/2023]
Abstract
In the context of native mass spectrometry, the development of gas-phase structural probes sensitive to the different levels of structuration of biomolecular assemblies is necessary to push forward conformational studies. In this paper, we provide the first example of the combination of ion mobility (IM) and Förster resonance energy transfer (FRET) measurements within the same experimental setup. The possibility to obtain mass- and mobility-resolved FRET measurements is demonstrated on a model peptide and applied to monitor the collision-induced unfolding of ubiquitin. Graphical Abstract ᅟ.
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Affiliation(s)
- Steven Daly
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière UMR 5306, F-69100, Villeurbanne, France
- Université de Bordeaux, INSERM U1212, CNRS UMR 5320, ARNA Laboratory, IECB, F-33600, Pessac, France
| | - Luke MacAleese
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière UMR 5306, F-69100, Villeurbanne, France
| | - Philippe Dugourd
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière UMR 5306, F-69100, Villeurbanne, France
| | - Fabien Chirot
- Univ Lyon, Université Claude Bernard Lyon 1, Ens de Lyon, CNRS, Institut des Sciences Analytiques UMR 5280, 5 rue de la Doua, F-69100, Villeurbanne, France.
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13
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Concentration Effect on Quenching of Chlorophyll a Fluorescence by All-Trans-β-Carotene in Photosynthesis. Molecules 2017; 22:molecules22101585. [PMID: 28934156 PMCID: PMC6151392 DOI: 10.3390/molecules22101585] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 09/20/2017] [Accepted: 09/20/2017] [Indexed: 11/17/2022] Open
Abstract
Absorption, fluorescence spectra of chlorophyll a (Chl-a) and all-trans-β-carotene (β-Car) mixing solution are investigated in different polarity and polarizability solvents. The carotenoids regulate the energy flow in photosynthesis by interaction with chlorophyll, leading to an observable reduction of Chl-a fluorescence. The fluorescence red shifts with the increasing solvent polarizability. The energy transfer in the Chl-a and β-Car system is proposed. The electron transfer should be dominant in quenching Chl-a fluorescence rather than the energy transfer in this system. Polar solvent with large polarizability shows high quenching efficiency. When dissolved in carbon tetrachloride, Chl-a presents red shift of absorption and blue shift of fluorescence spectra with increasing β-Car concentration, which implies a Chl-a conformational change.
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