1
|
Kumar G, Kellogg M, Dey S, Oliver TAA, Bradforth SE. Unraveling the Photoionization Dynamics of Indole in Aqueous and Ethanol Solutions. J Phys Chem B 2024; 128:4158-4170. [PMID: 38655896 DOI: 10.1021/acs.jpcb.4c01223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The photoionization dynamics of indole, the ultraviolet-B chromophore of tryptophan, were explored in water and ethanol using ultrafast transient absorption spectroscopy with 292, 268, and 200 nm excitation. By studying the femtosecond-to-nanosecond dynamics of indole in two different solvents, a new photophysical model has been generated that explains many previously unsolved facets of indole's complex solution phase photochemistry. Photoionization is only an active pathway for indole in aqueous solution, leading to a reduction in the fluorescence quantum yield in water-rich environments, which is frequently used in biophysical experiments as a key signature of the protein-folded state. Photoionization of indole in aqueous solution was observed for all three pump wavelengths but via two different mechanisms. For 200 nm excitation, electrons are ballistically ejected directly into the bulk solvent. Conversely, 292 and 268 nm excitation populates an admixture of two 1ππ* states, which form a dynamic equilibrium with a tightly bound indole cation and electron-ion pair. The ion pair dissociates on a nanosecond time scale, generating separated solvated electrons and indole cations. The charged species serve as important precursors to triplet indole production and greatly enhance the overall intersystem crossing rate. Our proposed photophysical model for indole in aqueous solution is the most appropriate for describing photoinduced dynamics of tryptophan in polypeptide sequences; tryptophan in aqueous pH 7 solution is zwitterionic, unlike in peptides, and resultantly has a competitive excited state proton transfer pathway that quenches the tryptophan fluorescence.
Collapse
Affiliation(s)
- Gaurav Kumar
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Michael Kellogg
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Shivalee Dey
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Thomas A A Oliver
- School of Chemistry, Cantock's Close, University of Bristol, Bristol BS8 1TS, U.K
| | - Stephen E Bradforth
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| |
Collapse
|
2
|
Jaiswal VK, Kabaciński P, Nogueira de Faria BE, Gentile M, de Paula AM, Borrego-Varillas R, Nenov A, Conti I, Cerullo G, Garavelli M. Environment-Driven Coherent Population Transfer Governs the Ultrafast Photophysics of Tryptophan. J Am Chem Soc 2022; 144:12884-12892. [PMID: 35796759 PMCID: PMC9305959 DOI: 10.1021/jacs.2c04565] [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: 11/29/2022]
Abstract
![]()
By combining UV transient
absorption spectroscopy with sub-30-fs
temporal resolution and CASPT2/MM calculations, we present a complete
description of the primary photoinduced processes in solvated tryptophan.
Our results shed new light on the role of the solvent in the relaxation
dynamics of tryptophan. We unveil two consecutive coherent population
transfer events involving the lowest two singlet excited states: a
sub-50-fs nonadiabatic La → Lb transfer
through a conical intersection and a subsequent 220 fs reverse Lb → La transfer due to solvent-assisted adiabatic
stabilization of the La state. Vibrational fingerprints
in the transient absorption spectra provide compelling evidence of
a vibronic coherence established between the two excited states from
the earliest times after photoexcitation and lasting until the back-transfer
to La is complete. The demonstration of response to the
environment as a driver of coherent population dynamics among the
excited states of tryptophan closes the long debate on its solvent-assisted
relaxation mechanisms and extends its application as a local probe
of protein dynamics to the ultrafast time scales.
Collapse
Affiliation(s)
- Vishal Kumar Jaiswal
- Dipartimento di Chimica industriale "Toso Montanari", Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| | - Piotr Kabaciński
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | | | - Marziogiuseppe Gentile
- Dipartimento di Chimica industriale "Toso Montanari", Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| | - Ana Maria de Paula
- Departamento de Física, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte-MG, Brazil
| | - Rocio Borrego-Varillas
- Istituto di Fotonica e Nanotecnologie, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Artur Nenov
- Dipartimento di Chimica industriale "Toso Montanari", Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| | - Irene Conti
- Dipartimento di Chimica industriale "Toso Montanari", Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy.,Istituto di Fotonica e Nanotecnologie, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Marco Garavelli
- Dipartimento di Chimica industriale "Toso Montanari", Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy
| |
Collapse
|
3
|
Nass Kovacs G, Colletier JP, Grünbein ML, Yang Y, Stensitzki T, Batyuk A, Carbajo S, Doak RB, Ehrenberg D, Foucar L, Gasper R, Gorel A, Hilpert M, Kloos M, Koglin JE, Reinstein J, Roome CM, Schlesinger R, Seaberg M, Shoeman RL, Stricker M, Boutet S, Haacke S, Heberle J, Heyne K, Domratcheva T, Barends TRM, Schlichting I. Three-dimensional view of ultrafast dynamics in photoexcited bacteriorhodopsin. Nat Commun 2019; 10:3177. [PMID: 31320619 PMCID: PMC6639342 DOI: 10.1038/s41467-019-10758-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 05/28/2019] [Indexed: 11/10/2022] Open
Abstract
Bacteriorhodopsin (bR) is a light-driven proton pump. The primary photochemical event upon light absorption is isomerization of the retinal chromophore. Here we used time-resolved crystallography at an X-ray free-electron laser to follow the structural changes in multiphoton-excited bR from 250 femtoseconds to 10 picoseconds. Quantum chemistry and ultrafast spectroscopy were used to identify a sequential two-photon absorption process, leading to excitation of a tryptophan residue flanking the retinal chromophore, as a first manifestation of multiphoton effects. We resolve distinct stages in the structural dynamics of the all-trans retinal in photoexcited bR to a highly twisted 13-cis conformation. Other active site sub-picosecond rearrangements include correlated vibrational motions of the electronically excited retinal chromophore, the surrounding amino acids and water molecules as well as their hydrogen bonding network. These results show that this extended photo-active network forms an electronically and vibrationally coupled system in bR, and most likely in all retinal proteins. Bacteriorhodopsin (bR) is a light-driven proton pump. Here the authors combine time-resolved crystallography at a free-electron laser, ultrafast spectroscopy and quantum chemistry to study the structural changes following multiphoton photoexcitation of bR and find that they occur within 300 fs not only in the light-absorbing chromophore but also in the surrounding protein.
Collapse
Affiliation(s)
- Gabriela Nass Kovacs
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Jacques-Philippe Colletier
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Marie Luise Grünbein
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Yang Yang
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Till Stensitzki
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Alexander Batyuk
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Sergio Carbajo
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - R Bruce Doak
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - David Ehrenberg
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Lutz Foucar
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Raphael Gasper
- Max-Planck-Institut für Molekulare Physiologie, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Alexander Gorel
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Mario Hilpert
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Marco Kloos
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Jason E Koglin
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Jochen Reinstein
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Christopher M Roome
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Ramona Schlesinger
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Matthew Seaberg
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Robert L Shoeman
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Miriam Stricker
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Sébastien Boutet
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA, 94025, USA
| | - Stefan Haacke
- Université de Strasbourg-CNRS, UMR 7504, IPCMS, 23 Rue du Loess, 67034, Strasbourg, France
| | - Joachim Heberle
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Karsten Heyne
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Tatiana Domratcheva
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany.
| | - Thomas R M Barends
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Ilme Schlichting
- Max-Planck-Institut für Medizinische Forschung, Jahnstraße 29, 69120, Heidelberg, Germany.
| |
Collapse
|
4
|
McCaslin TG, Pagba CV, Chi SH, Hwang HJ, Gumbart JC, Perry JW, Olivieri C, Porcelli F, Veglia G, Guo Z, McDaniel M, Barry BA. Structure and Function of Tryptophan-Tyrosine Dyads in Biomimetic β Hairpins. J Phys Chem B 2019; 123:2780-2791. [PMID: 30888824 PMCID: PMC6463897 DOI: 10.1021/acs.jpcb.8b12452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
![]()
Tyrosine–tryptophan (YW) dyads
are ubiquitous
structural motifs in enzymes and play roles in proton-coupled electron
transfer (PCET) and, possibly, protection from oxidative stress. Here,
we describe the function of YW dyads in de novo designed 18-mer, β
hairpins. In Peptide M, a YW dyad is formed between W14 and Y5. A
UV hypochromic effect and an excitonic Cotton signal are observed,
in addition to singlet, excited state (W*) and fluorescence emission
spectral shifts. In a second Peptide, Peptide MW, a Y5–W13
dyad is formed diagonally across the strand and distorts the backbone.
On a picosecond timescale, the W* excited-state decay kinetics are
similar in all peptides but are accelerated relative to amino acids
in solution. In Peptide MW, the W* spectrum is consistent with increased
conformational flexibility. In Peptide M and MW, the electron paramagnetic
resonance spectra obtained after UV photolysis are characteristic
of tyrosine and tryptophan radicals at 160 K. Notably, at pH 9, the
radical photolysis yield is decreased in Peptide M and MW, compared
to that in a tyrosine and tryptophan mixture. This protective effect
is not observed at pH 11 and is not observed in peptides containing
a tryptophan–histidine dyad or tryptophan alone. The YW dyad
protective effect is attributed to an increase in the radical recombination
rate. This increase in rate can be facilitated by hydrogen-bonding
interactions, which lower the barrier for the PCET reaction at pH
9. These results suggest that the YW dyad structural motif promotes
radical quenching under conditions of reactive oxygen stress.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Fernando Porcelli
- Department for Innovation in Biological, Agro-Food and Forest Systems , University of Tuscia , 01100 Viterbo , Italy
| | | | | | | | | |
Collapse
|
5
|
Roy A, Seidel R, Kumar G, Bradforth SE. Exploring Redox Properties of Aromatic Amino Acids in Water: Contrasting Single Photon vs Resonant Multiphoton Ionization in Aqueous Solutions. J Phys Chem B 2018. [DOI: 10.1021/acs.jpcb.7b11762] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anirban Roy
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Robert Seidel
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Gaurav Kumar
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Stephen E. Bradforth
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| |
Collapse
|
6
|
Safko TM, Kertesz M, Weiss RG. Photophysics of N,N-dimethyl-3-(1-indolyl)propan-1-ammonium chloride and related derivatives. Photochem Photobiol Sci 2017; 16:1546-1555. [PMID: 28876020 DOI: 10.1039/c7pp00199a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photophysical properties of two new indole derivatives have been examined by steady-state and dynamic spectroscopic methods. The ground-state structures and conformations of 3-(1-indolyl)-N,N-dimethylpropan-1-ammonium chloride (InCl) and 3-(1-indolyl)-N,N,N-trimethylpropan-1-ammonium chloride (MeInCl) have been examined through density functional theory calculations. These calculations reveal a preference for a 'closed' conformation which places the cationic ammonium group in proximity to the π-electron cloud in low polarity environments. This interaction is best described as an intramolecular hydrogen-π bond in the case of InCl and a cation-π interaction for MeInCl. The ground-state conformational equilibria are influenced by changes in the dielectric constant of the solvent, resulting in a variety of photophysical behaviors. The excitation/emission spectra, fluorescence quantum yields, and excited-state lifetimes, are reported for InCl, MeInCl, and a reference compound, 1-methylindole, in 1,4-dioxane (ε = 2), acetonitrile (ε = 37), and water (ε = 78) where solubility allows. Data from these solvents provide evidence for independent fluorescence quenching pathways for InCl and MeInCl. In addition, they lead to insights into the complexities of indole photophysics by demonstrating the sensitivity of the locally-excited states to changes in charge-density and solvent environment.
Collapse
Affiliation(s)
- Trevor M Safko
- Department of Chemistry, Georgetown University, 37th and O Streets, NW, Washington, DC 20057-1227, USA
| | | | | |
Collapse
|
7
|
Mathes T, Heilmann M, Pandit A, Zhu J, Ravensbergen J, Kloz M, Fu Y, Smith BO, Christie JM, Jenkins GI, Kennis JTM. Proton-Coupled Electron Transfer Constitutes the Photoactivation Mechanism of the Plant Photoreceptor UVR8. J Am Chem Soc 2015; 137:8113-20. [DOI: 10.1021/jacs.5b01177] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tilo Mathes
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Monika Heilmann
- Institute
of Molecular, Cell and Systems Biology, College of Medical, Veterinary
and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Anjali Pandit
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
- Department
of Solid-State NMR, Leiden Institute of Chemistry, Leiden University, Einsteinweg
55, 2333 CC Leiden, The Netherlands
| | - Jingyi Zhu
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Janneke Ravensbergen
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Miroslav Kloz
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Yinan Fu
- Institute
of Molecular, Cell and Systems Biology, College of Medical, Veterinary
and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Brian O. Smith
- Institute
of Molecular, Cell and Systems Biology, College of Medical, Veterinary
and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - John M. Christie
- Institute
of Molecular, Cell and Systems Biology, College of Medical, Veterinary
and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Gareth I. Jenkins
- Institute
of Molecular, Cell and Systems Biology, College of Medical, Veterinary
and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - John T. M. Kennis
- Biophysics
Section, Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| |
Collapse
|
8
|
Abstract
It was recently demonstrated that in ferric myoglobins (Mb) the fluorescence quenching of the photoexcited tryptophan 14 (*Trp(14)) residue is in part due to an electron transfer to the heme porphyrin (porph), turning it to the ferrous state. However, the invariance of *Trp decay times in ferric and ferrous Mbs raises the question as to whether electron transfer may also be operative in the latter. Using UV pump/visible probe transient absorption, we show that this is indeed the case for deoxy-Mb. We observe that the reduction generates (with a yield of about 30%) a low-valence Fe-porphyrin π [Fe(II)(porph(●-))] -anion radical, which we observe for the first time to our knowledge under physiological conditions. We suggest that the pathway for the electron transfer proceeds via the leucine 69 (Leu(69)) and valine 68 (Val(68)) residues. The results on ferric Mbs and the present ones highlight the generality of Trp-porphyrin electron transfer in heme proteins.
Collapse
|
9
|
Szabla R, Šponer J, Góra RW. Electron-Driven Proton Transfer Along H2O Wires Enables Photorelaxation of πσ* States in Chromophore-Water Clusters. J Phys Chem Lett 2015; 6:1467-1471. [PMID: 26263153 DOI: 10.1021/acs.jpclett.5b00261] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The fates of photochemically formed πσ* states are one of the central issues in photobiology due to their significant contribution to the photostability of biological matter, formation of hydrated electrons, and the phenomenon of photoacidity. Nevertheless, our understanding of the underlying molecular mechanisms in aqueous solution is still incomplete. In this paper, we report on the results of nonadiabatic photodynamics simulations of microhydrated 2-aminooxazole molecule employing algebraic diagrammatic construction to the second order. Our results indicate that electron-driven proton transfer along H2O wires induces the formation of πσ*/S0 state crossing and provides an effective deactivation channel. Because we recently have identified a similar channel for 4-aminoimidazole-5-carbonitrile [Szabla, R.; Phys. Chem. Chem. Phys. 2014, 16, 17617-17626 ], we conclude this mechanism may be quite common to all heterocyclic compounds with low-lying πσ* states.
Collapse
Affiliation(s)
- Rafał Szabla
- †Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic
| | - Jiří Šponer
- †Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic
- ‡CEITEC-Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, CZ-62500 Brno, Czech Republic
| | - Robert W Góra
- ¶Theoretical Chemistry Group, Institute of Physical and Theoretical Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| |
Collapse
|
10
|
Guglielmi M, Doemer M, Tavernelli I, Rothlisberger U. Photodynamics of Lys+-Trp protein motifs: Hydrogen bonds ensure photostability. Faraday Discuss 2013; 163:189-203; discussion 243-75. [DOI: 10.1039/c3fd00037k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
11
|
Tomasello G, Wohlgemuth M, Petersen J, Mitrić R. Photodynamics of Free and Solvated Tyrosine. J Phys Chem B 2012; 116:8762-70. [DOI: 10.1021/jp302179m] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gaia Tomasello
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, D-14195
Berlin, Germany
| | - Matthias Wohlgemuth
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, D-14195
Berlin, Germany
| | - Jens Petersen
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, D-14195
Berlin, Germany
| | - Roland Mitrić
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, D-14195
Berlin, Germany
| |
Collapse
|
12
|
Morisawa Y, Higashi N, Takaba K, Kariyama N, Goto T, Ikehata A, Ozaki Y. Development of a time-resolved attenuated total reflectance spectrometer in far-ultraviolet region. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:073103. [PMID: 22852667 DOI: 10.1063/1.4732846] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A far-ultraviolet transient absorption spectrometer based on time-resolved attenuated total reflectance (ATR) has been developed and tested for aqueous solutions of phenol and tryptophan in the region 170-185 nm. In this region, a stable tunable laser was not available, and therefore, white light from a laser-driven Xe lamp source was used. The time resolution, which was determined by the time response of a continuous light detector, was 40 ns. A new ATR cell where a sample liquid is exchanged continuously by a flow system was designed to reduce efficiently the stray light from the excitation light. We have tested the performance of the instrument by using aqueous solutions of phenol and tryptophan, whose photochemistry is already well known. Phenol and tryptophan have very strong absorptions due to a π-π∗ transition near 180 nm. Even for dilute solutions (10(-3) mol dm(-3)), we could observe decreases in their concentrations due to photochemistry that occurred upon their irradiation with a fourth harmonic generation laser pulse produced by an Nd:YAG laser. The sensitivity of the spectrometer was about 10(-4) abs, which corresponded to a concentration variation of 10(-3) mol dm(-3) for phenol and tryptophan.
Collapse
Affiliation(s)
- Yusuke Morisawa
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
| | | | | | | | | | | | | |
Collapse
|
13
|
Rondi A, Bonacina L, Trisorio A, Hauri C, Wolf JP. Coherent manipulation of free amino acids fluorescence. Phys Chem Chem Phys 2012; 14:9317-22. [PMID: 22395710 DOI: 10.1039/c2cp23357f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Coherent manipulation of molecular wavepackets in biomolecules might contribute to the quest towards label-free cellular imaging and protein identification. We report the use of optimally tailored UV laser pulses in pump-probe depletion experiments that selectively enhance or decrease fluorescence between two aromatic amino acids: tryptophan (Trp) and tyrosine (Tyr). Selective fluorescence modulation is achieved with a contrast of ~35%. A neat modification of the time-dependent fluorescence depletion signal of Trp is observed, while the Tyr transient trace remains unchanged. The mechanism invoked for explaining the change of the depletion of Trp is a less efficient coupling between the fluorescing state and the higher non-radiative excited states by the optimally shaped pulse, than by the reference pulse.
Collapse
Affiliation(s)
- A Rondi
- GAP-Biophotonics, University of Geneva, 22 ch. de Pinchat, CH-1211 Geneva 4, Switzerland
| | | | | | | | | |
Collapse
|
14
|
Gelot T, Tourón-Touceda P, Crégut O, Léonard J, Haacke S. Ultrafast site-specific fluorescence quenching of 2-aminopurine in a DNA hairpin studied by femtosecond down-conversion. J Phys Chem A 2012; 116:2819-25. [PMID: 22289047 DOI: 10.1021/jp212187m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ΔP(-)PBS analog of the DNA primary binding sequence (PBS) of the HIV-1 genome labeled at different positions by 2-aminopurine (2-AP) is investigated by a novel femtosecond fluorescence down-conversion experiment with 0.3-ps time resolution. The high signal-to-noise ratio of the fluorescence kinetics makes it possible to reveal four distinct decay times ranging from 0.8 ps to 2-3 ns for all the three labeling positions. This suggests the existence of at least four different quenching conformations of 2-AP with its nearest neighbors, and underscores the structural heterogeneity of the loop region of ΔP(-)PBS. Sub-5-ps components are found and attributed to stacking interactions of 2-AP with the flanking guanine (G) side chains, consistent with the NMR structure of ΔP(-)PBS. The observation of a significant increase of their total amplitude when 2-AP is positioned close to the rigid 3'-half of the G-rich stem gives further support to this assignment. Only a minor portion of conformations involves slow nanosecond collisional quenching.
Collapse
Affiliation(s)
- Thomas Gelot
- Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg- CNRS, 67034 Strasbourg, France
| | | | | | | | | |
Collapse
|