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Horz M, Masood HMA, Brunst H, Cerezo J, Picconi D, Vormann H, Niraghatam MS, van Wilderen LJGW, Bredenbeck J, Santoro F, Burghardt I. Vibrationally resolved two-photon electronic spectra including vibrational pre-excitation: Theory and application to VIPER spectroscopy with two-photon excitation. J Chem Phys 2023; 158:064201. [PMID: 36792506 DOI: 10.1063/5.0132608] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Following up on our previous work on vibrationally resolved electronic absorption spectra including the effect of vibrational pre-excitation [von Cosel et al., J. Chem. Phys. 147, 164116 (2017)], we present a combined theoretical and experimental study of two-photon-induced vibronic transitions in polyatomic molecules that are probed in the VIbrationally Promoted Electronic Resonance experiment using two-photon excitation (2P-VIPER). In order to compute vibronic spectra, we employ time-independent and time-dependent methods based on the evaluation of Franck-Condon overlap integrals and Fourier transformations of time-domain correlation functions, respectively. The time-independent approach uses a generalized version of the FCclasses method, while the time-dependent approach relies on the analytical evaluation of Gaussian moments within the harmonic approximation, including Duschinsky rotation effects. For the Coumarin 6 dye, two-dimensional 2P-VIPER experiments involving excitation to the lowest-lying singlet excited state (S1) are presented and compared with corresponding one-photon VIPER spectra. In both cases, coumarin ring modes and a CO stretch mode show VIPER activity, albeit with different relative intensities. Selective pre-excitation of these modes leads to a pronounced redshift of the low-frequency edge of the electronic absorption spectrum, which is a prerequisite for the VIPER experiment. Theoretical analysis underscores the role of interference between Franck-Condon and Herzberg-Teller effects in the two-photon experiment, which is at the root of the observed intensity distribution.
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Affiliation(s)
- Maximiliane Horz
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Hafiz M A Masood
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany
| | - Hendrik Brunst
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany
| | - Javier Cerezo
- Departamento de Química and Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - David Picconi
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Hannah Vormann
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Madhava Shyam Niraghatam
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
| | - Luuk J G W van Wilderen
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany
| | - Jens Bredenbeck
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt, Germany
| | - Fabrizio Santoro
- Consiglio Nazionale delle Ricerche - CNR, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), SS di Pisa, Via G. Moruzzi 1, I-56124 Pisa, Italy
| | - Irene Burghardt
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany
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Deniz E, Löffler JG, Kondratiev A, Thun AR, Shen Y, Wille G, Bredenbeck J. High-precision background correction and artifact suppression for ultrafast spectroscopy by quasi-simultaneous measurements in a split-sample cell. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:033001. [PMID: 35364971 DOI: 10.1063/5.0079958] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/03/2022] [Indexed: 06/14/2023]
Abstract
Alternating acquisition of background and sample spectra is often employed in conventional Fourier-transform infrared spectroscopy or ultraviolet-visible spectroscopy for accurate background subtraction. For example, for solvent background correction, typically a spectrum of a cuvette with solvent is measured and subtracted from a spectrum of a cuvette with solvent and solute. Ultrafast spectroscopies, though, come with many peculiarities that make the collection of well-matched, subtractable background and sample spectra challenging. Here, we present a demountable split-sample cell in combination with a modified Lissajous scanner to overcome these challenges. It allows for quasi-simultaneous measurements of background and sample spectra, mitigating the effects of drifts of the setup and maintaining the beam and sample geometry when swapping between background and sample measurements. The cell is moving between subsequent laser shots to refresh the excited sample volume. With less than 45 μl of solution for 150 μm optical thickness, sample usage is economical. Cell assembly is a key step and covered in an illustrated protocol.
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Affiliation(s)
- E Deniz
- Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - J G Löffler
- Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - A Kondratiev
- Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - A R Thun
- Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - Y Shen
- Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - G Wille
- Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - J Bredenbeck
- Institute of Biophysics, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
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Schmidt-Engler JM, von Berg S, Bredenbeck J. Temperature-Dependent Low-Frequency Modes in the Active Site of Bovine Carbonic Anhydrase II Probed by 2D-IR Spectroscopy. J Phys Chem Lett 2021; 12:7777-7782. [PMID: 34374547 DOI: 10.1021/acs.jpclett.1c01453] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Enzyme catalysis achieves tremendous rate accelerations. Enzyme reaction centers provide a constraint geometry that preferentially binds an activated form of the substrate and thus lowers the energy barrier. However, this transition state picture neglects the flexibility of proteins and its role in enzymatic catalysis. Especially for proton transfer reactions, it has been suggested that motions of the protein modulate the donor-acceptor distance and prepare a tunneling-ready state. We report the detection of frequency fluctuations of an azide anion (N3-) bound in the active site of the protein carbonic anhydrase II, where a low-frequency mode of the protein has been proposed to facilitate proton transfer over two water molecules during the catalyzed reaction. 2D-IR spectroscopy resolves an underdamped low-frequency mode at about 1 THz (30 cm-1). We find its frequency to be viscosity- and temperature-dependent and to decrease by 6 cm-1 between 230 and 320 K, reporting the softening of the mode's potential.
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Affiliation(s)
- Julian M Schmidt-Engler
- Institute of Biophysics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
| | - Sarah von Berg
- Institute of Biophysics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
| | - Jens Bredenbeck
- Institute of Biophysics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
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Through bonds or contacts? Mapping protein vibrational energy transfer using non-canonical amino acids. Nat Commun 2021; 12:3284. [PMID: 34078890 PMCID: PMC8172543 DOI: 10.1038/s41467-021-23591-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 05/06/2021] [Indexed: 11/08/2022] Open
Abstract
Vibrational energy transfer (VET) is essential for protein function. It is responsible for efficient energy dissipation in reaction sites, and has been linked to pathways of allosteric communication. While it is understood that VET occurs via backbone as well as via non-covalent contacts, little is known about the competition of these two transport channels, which determines the VET pathways. To tackle this problem, we equipped the β-hairpin fold of a tryptophan zipper with pairs of non-canonical amino acids, one serving as a VET injector and one as a VET sensor in a femtosecond pump probe experiment. Accompanying extensive non-equilibrium molecular dynamics simulations combined with a master equation analysis unravel the VET pathways. Our joint experimental/computational endeavor reveals the efficiency of backbone vs. contact transport, showing that even if cutting short backbone stretches of only 3 to 4 amino acids in a protein, hydrogen bonds are the dominant VET pathway.
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Schmidt-Engler JM, Zangl R, Guldan P, Morgner N, Bredenbeck J. Exploring the 2D-IR repertoire of the -SCN label to study site-resolved dynamics and solvation in the calcium sensor protein calmodulin. Phys Chem Chem Phys 2020; 22:5463-5475. [PMID: 32096510 DOI: 10.1039/c9cp06808b] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The calcium sensor protein calmodulin is ubiquitous among eukaryotes. It translates intracellular Ca2+ influx (by a decrease of conformational flexibility) into increased target recognition affinity. Here we demonstrate that by using the IR reporter -SCN in combination with 2D-IR spectroscopy, global structure changes and local dynamics, degree of solvent exposure and protein-ligand interaction can be characterised in great detail. The long vibrational lifetime of the -SCN label allows for centerline slope analysis of the 2D-IR line shape up to 120 ps to deduce the frequency-frequency correlation function (FFCF) of the -SCN label in various states and label positions in the protein. Based on that we show clear differences between a solvent exposed site, the environment close to the Ca2+ binding motif and three highly conserved positions for ligand binding. Furthermore, we demonstrate how these dynamics are affected by conformational change induced by the addition of Ca2+ ions and by interaction with a short helical peptide mimicking protein binding. We show that the binding mode is strongly heterogeneous among the probed key binding methionine residues. SCN's vibrational relaxation is dominated by intermolecular contributions. Changes in the vibrational lifetime upon changing between H2O and D2O buffer therefore provide a robust measure for water accessibility of the label. Characterising -SCN's extinction coefficient, vibrational lifetime in light and heavy water and its FFCF we demonstrate the vast potential it has as a label especially for nonlinear spectroscopies, such as 2D-IR spectroscopy.
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Affiliation(s)
- Julian M Schmidt-Engler
- Johann Wolfgang Goethe-University, Institute of Biophysics, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany.
| | - Rene Zangl
- Johann Wolfgang Goethe-University, Institute of Physical and Theoretical Chemistry, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany
| | - Patrick Guldan
- Johann Wolfgang Goethe-University, Institute of Biophysics, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany.
| | - Nina Morgner
- Johann Wolfgang Goethe-University, Institute of Physical and Theoretical Chemistry, Max-von-Laue-Str. 7, 60438 Frankfurt am Main, Germany
| | - Jens Bredenbeck
- Johann Wolfgang Goethe-University, Institute of Biophysics, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany.
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Schmidt-Engler JM, Blankenburg L, Zangl R, Hoffmann J, Morgner N, Bredenbeck J. Local dynamics of the photo-switchable protein PYP in ground and signalling state probed by 2D-IR spectroscopy of –SCN labels. Phys Chem Chem Phys 2020; 22:22963-22972. [DOI: 10.1039/d0cp04307a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We employ 2D-IR spectroscopy of the protein label –SCN to describe the local dynamics in the photo-switchable protein PYP in its dark state (pG) and after photoactivation, concomitant with vast structural rearrangements, in its signalling state (pB).
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Affiliation(s)
| | - Larissa Blankenburg
- Johann Wolfgang Goethe-University
- Institute of Biophysics
- 60438 Frankfurt am Main
- Germany
| | - Rene Zangl
- Johann Wolfgang Goethe-University
- Institute of Physical and Theoretical Chemistry
- Frankfurt am Main
- Germany
| | - Jan Hoffmann
- Johann Wolfgang Goethe-University
- Institute of Physical and Theoretical Chemistry
- Frankfurt am Main
- Germany
| | - Nina Morgner
- Johann Wolfgang Goethe-University
- Institute of Physical and Theoretical Chemistry
- Frankfurt am Main
- Germany
| | - Jens Bredenbeck
- Johann Wolfgang Goethe-University
- Institute of Biophysics
- 60438 Frankfurt am Main
- Germany
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Schmidt-Engler JM, Blankenburg L, Błasiak B, van Wilderen LJGW, Cho M, Bredenbeck J. Vibrational Lifetime of the SCN Protein Label in H 2O and D 2O Reports Site-Specific Solvation and Structure Changes During PYP's Photocycle. Anal Chem 2019; 92:1024-1032. [PMID: 31769286 DOI: 10.1021/acs.analchem.9b03997] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The application of vibrational labels such as thiocyanate (-S-C≡N) for studying protein structure and dynamics is thriving. Absorption spectroscopy is usually employed to obtain wavenumber and line shape of the label. An observable of great significance might be the vibrational lifetime, which can be obtained by pump probe or 2D-IR spectroscopy. Due to the insulating effect of the heavy sulfur atom in the case of the SCN label, the lifetime of the C≡N oscillator is expected to be particularly sensitive to its surrounding as it is not dominated by through-bond relaxation. We therefore investigate the vibrational lifetime of the SCN label at various positions in the blue light sensor protein Photoactive Yellow Protein (PYP) in the ground state and signaling state of the photoreceptor. We find that the vibrational lifetime of the C≡N stretching mode is strongly affected both by its protein environment and by the degree of exposure to the solvent. Even for label positions where the line shape and wavenumber observed by FTIR are barely changing upon activation of the photoreceptor, we find that the lifetime can change considerably. To obtain an unambiguous measure for the solvent exposure of the labeled site, we show that it is imperative to compare the lifetimes in H2O and D2O. Importantly, the lifetimes shorten in H2O as compared to D2O for water exposed labels, while they stay largely the same for buried labels. We quantify this effect by defining a solvent exclusion coefficient (SEC). The response of the label's vibrational lifetime to its solvent exposure renders it a suitable universal probe for protein investigations. This applies even to systems that are otherwise hard to address, such as transient or short-lived states, which could be created during a protein's working cycle (as here in PYP) or during protein folding. It is also applicable to flexible systems (intrinsically disordered proteins), protein-protein and protein-membrane interactions.
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Affiliation(s)
- Julian M Schmidt-Engler
- Johann Wolfgang Goethe-University , Institute of Biophysics , Max-von-Laue-Straße 1 , 60438 Frankfurt am Main , Germany
| | - Larissa Blankenburg
- Johann Wolfgang Goethe-University , Institute of Biophysics , Max-von-Laue-Straße 1 , 60438 Frankfurt am Main , Germany
| | - Bartosz Błasiak
- Johann Wolfgang Goethe-University , Institute of Biophysics , Max-von-Laue-Straße 1 , 60438 Frankfurt am Main , Germany
| | - Luuk J G W van Wilderen
- Johann Wolfgang Goethe-University , Institute of Biophysics , Max-von-Laue-Straße 1 , 60438 Frankfurt am Main , Germany
| | - Minhaeng Cho
- Institute of Basic Science , Center of Molecular Spectroscopy and Dynamics , 145 Anam-ro , Seongbuk-gu , Seoul 02841 , Republic of Korea.,Korea University , Department of Chemistry , 145 Anam-ro , Seongbuk-gu , Seoul 02841 , Republic of Korea
| | - Jens Bredenbeck
- Johann Wolfgang Goethe-University , Institute of Biophysics , Max-von-Laue-Straße 1 , 60438 Frankfurt am Main , Germany
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