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Lee S, Jue M, Lee K, Paulson B, Oh J, Cho M, Kim JK. Early-stage diagnosis of bladder cancer using surface-enhanced Raman spectroscopy combined with machine learning algorithms in a rat model. Biosens Bioelectron 2024; 246:115915. [PMID: 38081101 DOI: 10.1016/j.bios.2023.115915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/24/2023] [Accepted: 12/04/2023] [Indexed: 12/30/2023]
Abstract
Early diagnosis and accurate assessment of tumor development facilitate early bladder cancer resection and initiation of drug therapy. This study enabled an early, accurate, label-free, noninvasive diagnosis of bladder tumors by analyzing nano-biomarkers in a single drop of urine through surface-enhanced Raman spectroscopy (SERS). In a standard N-butyl-N-4-hydroxybutyl nitrosamine-induced rat model of bladder cancer, cancer stage and polyp tumor development were monitored using a small endoscope with a diameter of 1.2 mm in a minimally invasive manner without the need to kill the rats. Samples were divided into cancer-free, early-stage, and polyp-form cancer. Training data were classified according to micro-cystoscopic 5-aminolevulinic acid fluorescence diagnosis, and specimens were postmortem verified through histopathological analysis. A drop of urine from each sample group was placed on an Au-coated zinc oxide nanoporous chip to filter nano-biomaterials and selectively enhance the Raman signals of nanoscale analytes via SERS. Principal component analysis was used to reduce the dimensionality of the collected Raman spectra, and partial least squares discriminant analysis was used to find diagnostic clusters based on the labeled samples. The combination of SERS and machine learning achieved an accuracy ≥99.6% in diagnosing both early- and polyp-stage bladder tumors. With an area under the receiver operating characteristic curve greater than 0.996, the accuracy of the diagnosis in the rat model suggests that SERS-based diagnostic methods are promising when coupled with machine learning. Low-cost, label-free, and noninvasive surface-enhanced Raman spectra are ideal for developing clinically relevant point-of-care diagnostic techniques.
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Affiliation(s)
- Sanghwa Lee
- Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, 05505, Republic of Korea
| | - Miyeon Jue
- Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, 05505, Republic of Korea; Apollon, Inc., 68 Achasan-ro, Seongdong-gu, Seoul, 05505, Republic of Korea
| | - Kwanhee Lee
- Department of Biomedical Engineering, College of Medicine, University of Ulsan, Seoul, 05505, Republic of Korea
| | - Bjorn Paulson
- Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, 05505, Republic of Korea; Morgridge Institute for Research, Madison, WI, 53715, USA
| | - Jeongmin Oh
- Department of Biomedical Engineering, College of Medicine, University of Ulsan, Seoul, 05505, Republic of Korea
| | - Minju Cho
- Department of Biomedical Engineering, College of Medicine, University of Ulsan, Seoul, 05505, Republic of Korea
| | - Jun Ki Kim
- Biomedical Engineering Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, 05505, Republic of Korea; Department of Biomedical Engineering, College of Medicine, University of Ulsan, Seoul, 05505, Republic of Korea.
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2
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Lee S, Jue M, Cho M, Lee K, Paulson B, Jo H, Song JS, Kang S, Kim JK. Label-free atherosclerosis diagnosis through a blood drop of apolipoprotein E knockout mouse model using surface-enhanced Raman spectroscopy validated by machine learning algorithm. Bioeng Transl Med 2023; 8:e10529. [PMID: 37476064 PMCID: PMC10354754 DOI: 10.1002/btm2.10529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/28/2023] [Accepted: 04/12/2023] [Indexed: 07/22/2023] Open
Abstract
The direct preventative detection of flow-induced atherosclerosis remains a significant challenge, impeding the development of early treatments and prevention measures. This study proposes a method for diagnosing atherosclerosis in the carotid artery using nanometer biomarker measurements through surface-enhanced Raman spectroscopy (SERS) from single-drop blood samples. Atherosclerotic acceleration is induced in apolipoprotein E knockout mice which underwent a partial carotid ligation and were fed a high-fat diet to rapidly induce disturbed flow-induced atherosclerosis in the left common carotid artery while using the unligated, contralateral right carotid artery as control. The progressive atherosclerosis development of the left carotid artery was verified by micro-magnetic resonance imaging (micro-MRI) and histology in comparison to the right carotid artery. Single-drop blood samples are deposited on chips of gold-coated ZnO nanorods grown on silicon wafers that filter the nanometer markers and provide strong SERS signals. A diagnostic classifier was established based on principal component analysis (PCA), which separates the resultant spectra into the atherosclerotic and control groups. Scoring based on the principal components enabled the classification of samples into control, mild, and severe atherosclerotic disease. The PCA-based analysis was validated against an independent test sample and compared against the PCA-PLS-DA machine learning algorithm which is known for applicability to Raman diagnosis. The accuracy of the PCA modification-based diagnostic criteria was 94.5%, and that of the machine learning algorithm 97.5%. Using a mouse model, this study demonstrates that diagnosing and classifying the severity of atherosclerosis is possible using a single blood drop, SERS technology, and machine learning algorithm, indicating the detectability of biomarkers and vascular factors in the blood which correlate with the early stages of atherosclerosis development.
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Affiliation(s)
- Sanghwa Lee
- Biomedical Engineering Research CenterAsan Medical CenterSeoulRepublic of Korea
| | - Miyeon Jue
- Biomedical Engineering Research CenterAsan Medical CenterSeoulRepublic of Korea
| | - Minju Cho
- Biomedical Engineering Research CenterAsan Medical CenterSeoulRepublic of Korea
| | - Kwanhee Lee
- Biomedical Engineering Research CenterAsan Medical CenterSeoulRepublic of Korea
| | - Bjorn Paulson
- Biomedical Engineering Research CenterAsan Medical CenterSeoulRepublic of Korea
| | - Hanjoong Jo
- Wallace H. Coulter Department of Biomedical EngineeringEmory University and Georgia Institute of TechnologyAtlantaGeorgiaUSA
| | - Joon Seon Song
- Department of PathologyUniversity of Ulsan College of Medicine, Asan Medical CenterSeoulRepublic of Korea
| | - Soo‐Jin Kang
- Department of CardiologyUniversity of Ulsan College of Medicine, Asan Medical CenterSeoulRepublic of Korea
| | - Jun Ki Kim
- Biomedical Engineering Research CenterAsan Medical CenterSeoulRepublic of Korea
- Department of Biomedical EngineeringUniversity of Ulsan, College of MedicineSeoulRepublic of Korea
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3
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Lee S, Oh J, Lee K, Cho M, Paulson B, Kim JK. Diagnosis of Ischemic Renal Failure Using Surface-Enhanced Raman Spectroscopy and a Machine Learning Algorithm. Anal Chem 2022; 94:17477-17484. [PMID: 36480771 DOI: 10.1021/acs.analchem.2c03634] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
To diagnose renal function using a biochip capable of detecting SERS and to assess Raman measurements taken from a bilateral renal ischemia model and the feasibility of early diagnosis was done. After generating a bilateral renal ischemia rat model, blood and urine were collected. After confirming the presence of renal injury and function, liquid drops were placed onto a Raman chip whose surface had been enhanced with Au-ZnO nanorods. SERS biomarkers that diffused into the nanogaps were selectively amplified. Raman signals varied based on the severity of the renal function, and these differences were confirmed statistically. These results confirm that renal ischemia leads to renal dysfunction and that surface-enhanced Raman spectroscopy and a machine learning algorithm can be used to track signals in the urine from the release of SERS biomarkers.
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Affiliation(s)
- Sanghwa Lee
- Biomedical Engineering Research Center, Asan Medical Center, Seoul 05505, Republic of Korea
| | - Jeongmin Oh
- Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea
| | - Kwanhee Lee
- Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea
| | - Minju Cho
- Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea
| | - Bjorn Paulson
- Biomedical Engineering Research Center, Asan Medical Center, Seoul 05505, Republic of Korea
| | - Jun Ki Kim
- Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 05505, Republic of Korea
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4
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El Khoury Y, Le Breton G, Cunha AV, Jansen TLC, van Wilderen LJGW, Bredenbeck J. Lessons from combined experimental and theoretical examination of the FTIR and 2D-IR spectroelectrochemistry of the amide I region of cytochrome c. J Chem Phys 2021; 154:124201. [PMID: 33810651 DOI: 10.1063/5.0039969] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Amide I difference spectroscopy is widely used to investigate protein function and structure changes. In this article, we show that the common approach of assigning features in amide I difference signals to distinct secondary structure elements in many cases may not be justified. Evidence comes from Fourier transform infrared (FTIR) and 2D-IR spectroelectrochemistry of the protein cytochrome c in the amide I range, in combination with computational spectroscopy based on molecular dynamics (MD) simulations. This combination reveals that each secondary structure unit, such as an alpha-helix or a beta-sheet, exhibits broad overlapping contributions, usually spanning a large part of the amide I region, which in the case of difference absorption experiments (such as in FTIR spectroelectrochemistry) may lead to intensity-compensating and even sign-changing contributions. We use cytochrome c as the test case, as this small electron-transferring redox-active protein contains different kinds of secondary structure units. Upon switching its redox-state, the protein exhibits a different charge distribution while largely retaining its structural scaffold. Our theoretical analysis suggests that the change in charge distribution contributes to the spectral changes and that structural changes are small. However, in order to confidently interpret FTIR amide I difference signals in cytochrome c and proteins in general, MD simulations in combination with additional experimental approaches such as isotope labeling, the insertion of infrared labels to selectively probe local structural elements will be required. In case these data are not available, a critical assessment of previous interpretations of protein amide I 1D- and 2D-IR difference spectroscopy data is warranted.
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Affiliation(s)
- Youssef El Khoury
- Institut für Biophysik, Johann-Wolfgang-Goethe-Universität, Max-von-Laue-Strasse. 1, 60438 Frankfurt am Main, Germany
| | - Guillaume Le Breton
- University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Ana V Cunha
- University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Thomas L C Jansen
- University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Luuk J G W van Wilderen
- Institut für Biophysik, Johann-Wolfgang-Goethe-Universität, Max-von-Laue-Strasse. 1, 60438 Frankfurt am Main, Germany
| | - Jens Bredenbeck
- Institut für Biophysik, Johann-Wolfgang-Goethe-Universität, Max-von-Laue-Strasse. 1, 60438 Frankfurt am Main, Germany
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Baiz CR, Błasiak B, Bredenbeck J, Cho M, Choi JH, Corcelli SA, Dijkstra AG, Feng CJ, Garrett-Roe S, Ge NH, Hanson-Heine MWD, Hirst JD, Jansen TLC, Kwac K, Kubarych KJ, Londergan CH, Maekawa H, Reppert M, Saito S, Roy S, Skinner JL, Stock G, Straub JE, Thielges MC, Tominaga K, Tokmakoff A, Torii H, Wang L, Webb LJ, Zanni MT. Vibrational Spectroscopic Map, Vibrational Spectroscopy, and Intermolecular Interaction. Chem Rev 2020; 120:7152-7218. [PMID: 32598850 PMCID: PMC7710120 DOI: 10.1021/acs.chemrev.9b00813] [Citation(s) in RCA: 160] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Vibrational spectroscopy is an essential tool in chemical analyses, biological assays, and studies of functional materials. Over the past decade, various coherent nonlinear vibrational spectroscopic techniques have been developed and enabled researchers to study time-correlations of the fluctuating frequencies that are directly related to solute-solvent dynamics, dynamical changes in molecular conformations and local electrostatic environments, chemical and biochemical reactions, protein structural dynamics and functions, characteristic processes of functional materials, and so on. In order to gain incisive and quantitative information on the local electrostatic environment, molecular conformation, protein structure and interprotein contacts, ligand binding kinetics, and electric and optical properties of functional materials, a variety of vibrational probes have been developed and site-specifically incorporated into molecular, biological, and material systems for time-resolved vibrational spectroscopic investigation. However, still, an all-encompassing theory that describes the vibrational solvatochromism, electrochromism, and dynamic fluctuation of vibrational frequencies has not been completely established mainly due to the intrinsic complexity of intermolecular interactions in condensed phases. In particular, the amount of data obtained from the linear and nonlinear vibrational spectroscopic experiments has been rapidly increasing, but the lack of a quantitative method to interpret these measurements has been one major obstacle in broadening the applications of these methods. Among various theoretical models, one of the most successful approaches is a semiempirical model generally referred to as the vibrational spectroscopic map that is based on a rigorous theory of intermolecular interactions. Recently, genetic algorithm, neural network, and machine learning approaches have been applied to the development of vibrational solvatochromism theory. In this review, we provide comprehensive descriptions of the theoretical foundation and various examples showing its extraordinary successes in the interpretations of experimental observations. In addition, a brief introduction to a newly created repository Web site (http://frequencymap.org) for vibrational spectroscopic maps is presented. We anticipate that a combination of the vibrational frequency map approach and state-of-the-art multidimensional vibrational spectroscopy will be one of the most fruitful ways to study the structure and dynamics of chemical, biological, and functional molecular systems in the future.
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Affiliation(s)
- Carlos R. Baiz
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, U.S.A
| | - Bartosz Błasiak
- Department of Physical and Quantum Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Jens Bredenbeck
- Johann Wolfgang Goethe-University, Institute of Biophysics, Max-von-Laue-Str. 1, 60438, Frankfurt am Main, Germany
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics, Seoul 02841, Republic of Korea
- Department of Chemistry, Korea University, Seoul 02841, Republic of Korea
| | - Jun-Ho Choi
- Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | - Steven A. Corcelli
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, U.S.A
| | - Arend G. Dijkstra
- School of Chemistry and School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, U.K
| | - Chi-Jui Feng
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, U.S.A
| | - Sean Garrett-Roe
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, U.S.A
| | - Nien-Hui Ge
- Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025, U.S.A
| | - Magnus W. D. Hanson-Heine
- School of Chemistry, University of Nottingham, Nottingham, University Park, Nottingham, NG7 2RD, U.K
| | - Jonathan D. Hirst
- School of Chemistry, University of Nottingham, Nottingham, University Park, Nottingham, NG7 2RD, U.K
| | - Thomas L. C. Jansen
- University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Kijeong Kwac
- Center for Molecular Spectroscopy and Dynamics, Seoul 02841, Republic of Korea
| | - Kevin J. Kubarych
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, MI 48109, U.S.A
| | - Casey H. Londergan
- Department of Chemistry, Haverford College, Haverford, Pennsylvania 19041, U.S.A
| | - Hiroaki Maekawa
- Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025, U.S.A
| | - Mike Reppert
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Shinji Saito
- Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki, 444-8585, Japan
| | - Santanu Roy
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110, U.S.A
| | - James L. Skinner
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637, U.S.A
| | - Gerhard Stock
- Biomolecular Dynamics, Institute of Physics, Albert Ludwigs University, 79104 Freiburg, Germany
| | - John E. Straub
- Department of Chemistry, Boston University, Boston, MA 02215, U.S.A
| | - Megan C. Thielges
- Department of Chemistry, Indiana University, 800 East Kirkwood, Bloomington, Indiana 47405, U.S.A
| | - Keisuke Tominaga
- Molecular Photoscience Research Center, Kobe University, Nada, Kobe 657-0013, Japan
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, U.S.A
| | - Hajime Torii
- Department of Applied Chemistry and Biochemical Engineering, Faculty of Engineering, and Department of Optoelectronics and Nanostructure Science, Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-Ku, Hamamatsu 432-8561, Japan
| | - Lu Wang
- Department of Chemistry and Chemical Biology, Institute for Quantitative Biomedicine, Rutgers University, 174 Frelinghuysen Road, Piscataway, NJ 08854, U.S.A
| | - Lauren J. Webb
- Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street, STOP A5300, Austin, Texas 78712, U.S.A
| | - Martin T. Zanni
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706-1396, U.S.A
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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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7
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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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8
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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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9
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Blankenburg L, Schroeder L, Habenstein F, Błasiak B, Kottke T, Bredenbeck J. Following local light-induced structure changes and dynamics of the photoreceptor PYP with the thiocyanate IR label. Phys Chem Chem Phys 2019; 21:6622-6634. [PMID: 30855039 DOI: 10.1039/c8cp05399e] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoactive Yellow Protein (PYP) is a bacterial blue light receptor that enters a photocycle after excitation. The intermediate states are formed on time scales ranging from femtoseconds up to hundreds of milliseconds, after which the signaling state with a lifetime of about 1 s is reached. To investigate structural changes and dynamics, we incorporated the SCN IR label at distinct positions of the photoreceptor via cysteine mutation and cyanylation. FT-IR measurements of the SCN label at different sites of the well-established dark state structure of PYP characterized the spectral response of the label to differences in the environment. Under constant blue light irradiation, we observed the formation of the signaling state with significant changes of wavenumber and lineshape of the SCN bands. Thereby we deduced light-induced structural changes in the local environment of the labels. These results were supported by molecular dynamics simulations on PYP providing the solvent accessible surface area (SASA) at the different positions. To follow protein dynamics via the SCN label during the photocycle, we performed step-scan FT-IR measurements with a time resolution of 10 μs. Global analysis yielded similar time constants of τ1 = 70 μs, τ2 = 640 μs, and τ3 > 20 ms for the wild type and τ1 = 36 μs, τ2 = 530 μs, and τ3 > 20 ms for the SCN-labeled mutant PYP-A44C*, a mutant which provided a sufficiently large SCN difference signal to measure step-scan FT-IR spectra. In comparison to the protein (amide, E46) and chromophore bands the dynamics of the SCN label show a different behavior. This result indicates that the local kinetics sensed by the label are different from the global protein kinetics.
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Affiliation(s)
- Larissa Blankenburg
- Johann Wolfgang Goethe-University, Institute of Biophysics, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany.
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10
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van Wilderen LJGW, Brunst H, Gustmann H, Wachtveitl J, Broos J, Bredenbeck J. Cyano-tryptophans as dual infrared and fluorescence spectroscopic labels to assess structural dynamics in proteins. Phys Chem Chem Phys 2018; 20:19906-19915. [DOI: 10.1039/c8cp00846a] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
By moving the cyano group position on the indole ring, both artificial amino acids report differently to their microscopic environment.
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Affiliation(s)
| | - H. Brunst
- Institute of Biophysics
- Johann-Wolfgang-Goethe Universität
- Frankfurt am Main
- Germany
| | - H. Gustmann
- Institute of Physical and Theoretical Chemistry
- Johann-Wolfgang-Goethe Universität
- Frankfurt am Main
- Germany
| | - J. Wachtveitl
- Institute of Physical and Theoretical Chemistry
- Johann-Wolfgang-Goethe Universität
- Frankfurt am Main
- Germany
| | - J. Broos
- Laboratory of Biophysical Chemistry and GBB (Groningen Biomolecular Science and Biotechnology Institute)
- University of Groningen
- 9747 AG Groningen
- The Netherlands
| | - J. Bredenbeck
- Institute of Biophysics
- Johann-Wolfgang-Goethe Universität
- Frankfurt am Main
- Germany
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