1
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Jaufer AM, Bouhadana A, Kharrazizadeh A, Zhou M, Colina CM, Fanucci GE. Designing surface exposed sites on Bacillus subtilis lipase A for spin-labeling and hydration studies. Biophys Chem 2024; 308:107203. [PMID: 38382282 DOI: 10.1016/j.bpc.2024.107203] [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: 01/19/2024] [Revised: 02/09/2024] [Accepted: 02/15/2024] [Indexed: 02/23/2024]
Abstract
Spin-labeling with electron paramagnetic resonance spectroscopy (EPR) is a facile method for interrogating macromolecular flexibility, conformational changes, accessibility, and hydration. Within we present a computationally based approach for the rational selection of reporter sites in Bacillus subtilis lipase A (BSLA) for substitution to cysteine residues with subsequent modification with a spin-label that are expected to not significantly perturb the wild-type structure, dynamics, or enzymatic function. Experimental circular dichroism spectroscopy, Michaelis-Menten kinetic parameters and EPR spectroscopy data validate the success of this approach to computationally select reporter sites for future magnetic resonance investigations of hydration and hydration changes induced by polymer conjugation, tethering, immobilization, or amino acid substitution in BSLA. Analysis of molecular dynamic simulations of the impact of substitutions on the secondary structure agree well with experimental findings. We propose that this computationally guided approach for choosing spin-labeled EPR reporter sites, which evaluates relative surface accessibility coupled with hydrogen bonding occupancy of amino acids to the catalytic pocket via atomistic simulations, should be readily transferable to other macromolecular systems of interest including selecting sites for paramagnetic relaxation enhancement NMR studies, other spin-labeling EPR studies or any method requiring a tagging method where it is desirable to not alter enzyme stability or activity.
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Affiliation(s)
- Afnan M Jaufer
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA; George and Josephine Butler Polymer Research Laboratory, University of Florida, Gainesville, FL 32611, USA.
| | - Adam Bouhadana
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Amir Kharrazizadeh
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Mingwei Zhou
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Coray M Colina
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA; George and Josephine Butler Polymer Research Laboratory, University of Florida, Gainesville, FL 32611, USA; Department of Materials Science and Engineering, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
| | - Gail E Fanucci
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611, USA.
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2
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Ackermann K, Heubach CA, Schiemann O, Bode BE. Pulse Dipolar Electron Paramagnetic Resonance Spectroscopy Distance Measurements at Low Nanomolar Concentrations: The Cu II-Trityl Case. J Phys Chem Lett 2024; 15:1455-1461. [PMID: 38294197 PMCID: PMC10860127 DOI: 10.1021/acs.jpclett.3c03311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 01/11/2024] [Accepted: 01/19/2024] [Indexed: 02/01/2024]
Abstract
Recent sensitivity enhancements in pulse dipolar electron paramagnetic resonance spectroscopy (PDS) have afforded distance measurements at submicromolar spin concentrations. This development opens the path for new science as more biomolecular systems can be investigated at their respective physiological concentrations. Here, we demonstrate that the combination of orthogonal spin-labeling using CuII ions and trityl yields a >3-fold increase in sensitivity compared to that of the established CuII-nitroxide labeling strategy. Application of the recently developed variable-time relaxation-induced dipolar modulation enhancement (RIDME) method yields a further ∼2.5-fold increase compared to the commonly used constant-time RIDME. This overall increase in sensitivity of almost an order of magnitude makes distance measurements in the range of 3 nm with protein concentrations as low as 10 nM feasible, >2 times lower than the previously reported concentration. We expect that experiments at single-digit nanomolar concentrations are imminent, which have the potential to transform biological PDS applications.
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Affiliation(s)
- Katrin Ackermann
- EaStCHEM
School of Chemistry and Biomedical Sciences Research Complex, Centre
of Magnetic Resonance, University of St
Andrews, North Haugh, St Andrews KY16 9ST, U.K.
| | - Caspar A. Heubach
- Clausius-Institute
of Physical and Theoretical Chemistry, University
of Bonn, Wegelerstrasse 12, 53115 Bonn, Germany
| | - Olav Schiemann
- Clausius-Institute
of Physical and Theoretical Chemistry, University
of Bonn, Wegelerstrasse 12, 53115 Bonn, Germany
| | - Bela E. Bode
- EaStCHEM
School of Chemistry and Biomedical Sciences Research Complex, Centre
of Magnetic Resonance, University of St
Andrews, North Haugh, St Andrews KY16 9ST, U.K.
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3
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Bogetti X, Bogetti A, Casto J, Rule G, Chong L, Saxena S. Direct observation of negative cooperativity in a detoxification enzyme at the atomic level by Electron Paramagnetic Resonance spectroscopy and simulation. Protein Sci 2023; 32:e4770. [PMID: 37632831 PMCID: PMC10503414 DOI: 10.1002/pro.4770] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/14/2023] [Accepted: 08/23/2023] [Indexed: 08/28/2023]
Abstract
The catalytic activity of human glutathione S-transferase A1-1 (hGSTA1-1), a homodimeric detoxification enzyme, is dependent on the conformational dynamics of a key C-terminal helix α9 in each monomer. However, the structural details of how the two monomers interact upon binding of substrates is not well understood and the structure of the ligand-free state of the hGSTA1-1 homodimer has not been resolved. Here, we used a combination of electron paramagnetic resonance (EPR) distance measurements and weighted ensemble (WE) simulations to characterize the conformational ensemble of the ligand-free state at the atomic level. EPR measurements reveal a broad distance distribution between a pair of Cu(II) labels in the ligand-free state that gradually shifts and narrows as a function of increasing ligand concentration. These shifts suggest changes in the relative positioning of the two α9 helices upon ligand binding. WE simulations generated unbiased pathways for the seconds-timescale transition between alternate states of the enzyme, leading to the generation of atomically detailed structures of the ligand-free state. Notably, the simulations provide direct observations of negative cooperativity between the monomers of hGSTA1-1, which involve the mutually exclusive docking of α9 in each monomer as a lid over the active site. We identify key interactions between residues that lead to this negative cooperativity. Negative cooperativity may be essential for interaction of hGSTA1-1 with a wide variety of toxic substrates and their subsequent neutralization. More broadly, this work demonstrates the power of integrating EPR distances with WE rare-events sampling strategy to gain mechanistic information on protein function at the atomic level.
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Affiliation(s)
- Xiaowei Bogetti
- Department of ChemistryUniversity of PittsburghPittsburghPennsylvaniaUSA
| | - Anthony Bogetti
- Department of ChemistryUniversity of PittsburghPittsburghPennsylvaniaUSA
| | - Joshua Casto
- Department of ChemistryUniversity of PittsburghPittsburghPennsylvaniaUSA
| | - Gordon Rule
- Department of Biological SciencesCarnegie Mellon UniversityPittsburghPennsylvaniaUSA
| | - Lillian Chong
- Department of ChemistryUniversity of PittsburghPittsburghPennsylvaniaUSA
| | - Sunil Saxena
- Department of ChemistryUniversity of PittsburghPittsburghPennsylvaniaUSA
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4
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Shenberger Y, Gevorkyan-Airapetov L, Hirsch M, Hofmann L, Ruthstein S. An in-cell spin-labelling methodology provides structural information on cytoplasmic proteins in bacteria. Chem Commun (Camb) 2023; 59:10524-10527. [PMID: 37563959 DOI: 10.1039/d3cc03047d] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
EPR in-cell spin-labeling was applied to CueR in E. coli. The methodology employed a Cu(II)-NTA complexed with dHis. High resolved in-cell distance distributions were obtained revealing minor differences between in vitro and in-cell data. This methodology allows study of structural changes of any protein in-cell, independent of size or cellular system.
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Affiliation(s)
- Yulia Shenberger
- Department of Chemistry, Faculty of Exact Sciences and Institute of Nanotechnology and Advanced Materials, Bar Ilan university, 5290002, Israel.
| | - Lada Gevorkyan-Airapetov
- Department of Chemistry, Faculty of Exact Sciences and Institute of Nanotechnology and Advanced Materials, Bar Ilan university, 5290002, Israel.
| | - Melanie Hirsch
- Department of Chemistry, Faculty of Exact Sciences and Institute of Nanotechnology and Advanced Materials, Bar Ilan university, 5290002, Israel.
| | - Lukas Hofmann
- Department of Chemistry, Faculty of Exact Sciences and Institute of Nanotechnology and Advanced Materials, Bar Ilan university, 5290002, Israel.
| | - Sharon Ruthstein
- Department of Chemistry, Faculty of Exact Sciences and Institute of Nanotechnology and Advanced Materials, Bar Ilan university, 5290002, Israel.
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5
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Wort JL, Ackermann K, Giannoulis A, Bode BE. Enhanced sensitivity for pulse dipolar EPR spectroscopy using variable-time RIDME. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 352:107460. [PMID: 37167826 DOI: 10.1016/j.jmr.2023.107460] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 04/03/2023] [Accepted: 04/19/2023] [Indexed: 05/13/2023]
Abstract
Pulse dipolar EPR spectroscopy (PDS) measurements are an important complementary tool in structural biology and are increasingly applied to macromolecular assemblies implicated in human health and disease at physiological concentrations. This requires ever higher sensitivity, and recent advances have driven PDS measurements into the mid-nanomolar concentration regime, though optimization and acquisition of such measurements remains experimentally demanding and time expensive. One important consideration is that constant-time acquisition represents a hard limit for measurement sensitivity, depending on the maximum measured distance. Determining this distance a priori has been facilitated by machine-learning structure prediction (AlphaFold2 and RoseTTAFold) but is often confounded by non-representative behaviour in frozen solution that may mandate multiple rounds of optimization and acquisition. Herein, we endeavour to simultaneously enhance sensitivity and streamline PDS measurement optimization to one-step by benchmarking a variable-time acquisition RIDME experiment applied to CuII-nitroxide and CuII-CuII model systems. Results demonstrate marked sensitivity improvements of both 5- and 6-pulse variable-time RIDME of between 2- and 5-fold over the constant-time analogues.
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Affiliation(s)
- Joshua L Wort
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Angeliki Giannoulis
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland.
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6
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Tabares LC, Daniel DT, Vázquez-Ibar JL, Kouklovsky C, Alezra V, Un S. Using the Noncanonical Metallo-Amino Acid [Cu(II)(2,2'-Bipyridin-5-yl)]-alanine to Study the Structures of Proteins. J Phys Chem Lett 2023; 14:3368-3375. [PMID: 36995079 DOI: 10.1021/acs.jpclett.3c00196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Genetic code expansion allows modification of the physical and chemical properties of proteins by the site-directed insertion of noncanonical amino acids. Here we exploit this technology for measuring nanometer-scale distances in proteins. (2,2'-Bipyridin-5-yl)alanine was incorporated into the green fluorescent protein (GFP) and used as an anchoring point for Cu(II) to create a spin-label. The incorporation of (2,2'-bipyridin-5-yl)alanine directly into the protein resulted in a high-affinity binding site for Cu(II) capable of outcompeting other binding positions in the protein. The resulting Cu(II)-spin label is very compact and not larger than a conventional amino acid. By using 94 GHz electron paramagnetic resonance (EPR) pulse dipolar spectroscopy we have been able to determine accurately the distance between two such spin-labels. Our measurements revealed that GFP dimers can adopt different quaternary conformations. The combination of spin-labeling using a paramagnetic nonconventional amino acid with high-frequency EPR techniques resulted in a sensitive method for studying the structures of proteins.
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Affiliation(s)
- Leandro C Tabares
- Institute for Integrative Biology of the Cell, Department of Biochemistry, Biophysics and Structural Biology, Université Paris-Saclay, CEA, CNRS UMR 9198, CEA-Saclay, Gif-sur-Yvette F-91198, France
| | - Davis T Daniel
- Institute for Integrative Biology of the Cell, Department of Biochemistry, Biophysics and Structural Biology, Université Paris-Saclay, CEA, CNRS UMR 9198, CEA-Saclay, Gif-sur-Yvette F-91198, France
| | - José Luis Vázquez-Ibar
- Institute for Integrative Biology of the Cell, Department of Biochemistry, Biophysics and Structural Biology, Université Paris-Saclay, CEA, CNRS UMR 9198, CEA-Saclay, Gif-sur-Yvette F-91198, France
| | - Cyrille Kouklovsky
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Saclay, CNRS, Orsay F-91405, Cedex France
| | - Valérie Alezra
- Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Saclay, CNRS, Orsay F-91405, Cedex France
| | - Sun Un
- Institute for Integrative Biology of the Cell, Department of Biochemistry, Biophysics and Structural Biology, Université Paris-Saclay, CEA, CNRS UMR 9198, CEA-Saclay, Gif-sur-Yvette F-91198, France
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7
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Casto J, Bogetti X, Hunter HR, Hasanbasri Z, Saxena S. "Store-bought is fine": Sensitivity considerations using shaped pulses for DEER measurements on Cu(II) labels. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 349:107413. [PMID: 36867974 DOI: 10.1016/j.jmr.2023.107413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/27/2023] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
The narrow excitation bandwidth of monochromic pulses is a sensitivity limitation for pulsed dipolar spectroscopy on Cu(II)-based measurements. In response, frequency-swept pulses with large excitation bandwidths have been adopted to probe a greater range of the EPR spectrum. However, much of the work utilizing frequency-swept pulses in Cu(II) distance measurements has been carried out on home-built spectrometers and equipment. Herein, we carry out systematic Cu(II) based distance measurements to demonstrate the capability of chirp pulses on commercial instrumentation. More importantly we delineate sensitivity considerations under acquisition schemes that are necessary for robust distance measurements using Cu(II) labels for proteins. We show that a 200 MHz sweeping bandwidth chirp pulse can improve the sensitivity of long-range distance measurements by factors of three to four. The sensitivity of short-range distances only increases slightly due to special considerations for the chirp pulse duration relative to the period length of the modulated dipolar signal. Enhancements in sensitivity also dramatically reduce measurement collection times enabling rapid collection of orientationally averaged Cu(II) distance measurements in under two hours.
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Affiliation(s)
- Joshua Casto
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Hannah R Hunter
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Zikri Hasanbasri
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States.
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8
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Ackermann K, Khazaipoul S, Wort JL, Sobczak AIS, Mkami HE, Stewart AJ, Bode BE. Investigating Native Metal Ion Binding Sites in Mammalian Histidine-Rich Glycoprotein. J Am Chem Soc 2023; 145:8064-8072. [PMID: 37001144 PMCID: PMC10103162 DOI: 10.1021/jacs.3c00587] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
Mammalian histidine-rich glycoprotein (HRG) is a highly versatile and abundant blood plasma glycoprotein with a diverse range of ligands that is involved in regulating many essential biological processes, including coagulation, cell adhesion, and angiogenesis. Despite its biomedical importance, structural information on the multi-domain protein is sparse, not least due to intrinsically disordered regions that elude high-resolution structural characterization. Binding of divalent metal ions, particularly ZnII, to multiple sites within the HRG protein is of critical functional importance and exerts a regulatory role. However, characterization of the ZnII binding sites of HRG is a challenge; their number and composition as well as their affinities and stoichiometries of binding are currently not fully understood. In this study, we explored modern electron paramagnetic resonance (EPR) spectroscopy methods supported by protein secondary and tertiary structure prediction to assemble a holistic picture of native HRG and its interaction with metal ions. To the best of our knowledge, this is the first time that this suite of EPR techniques has been applied to count and characterize endogenous metal ion binding sites in a native mammalian protein of unknown structure.
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Affiliation(s)
- Katrin Ackermann
- EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
| | - Siavash Khazaipoul
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, Scotland
| | - Joshua L. Wort
- EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
| | - Amélie I. S. Sobczak
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, Scotland
| | - Hassane El Mkami
- Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, Scotland
| | - Alan J. Stewart
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- School of Medicine, University of St Andrews, North Haugh, St Andrews KY16 9TF, Scotland
| | - Bela E. Bode
- EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
- Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, Scotland
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9
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Rogers CJ, Asthana D, Brookfield A, Chiesa A, Timco GA, Collison D, Natrajan LS, Carretta S, Winpenny REP, Bowen AM. Modelling Conformational Flexibility in a Spectrally Addressable Molecular Multi‐Qubit Model System. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ciarán J. Rogers
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Deepak Asthana
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
- Department of Chemistry Ashoka University Sonipat Haryana India
| | - Adam Brookfield
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Alessandro Chiesa
- Dipartimento di Scienze Matematiche Fisiche e Informatiche Università di Parma 43124 Parma Italy
- INFN–Sezione di Milano-Bicocca Gruppo Collegato di Parma I-43124 Parma Italy
- UdR Parma INSTM I-43124 Parma Italy
| | - Grigore A. Timco
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
| | - David Collison
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Louise S. Natrajan
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Stefano Carretta
- Dipartimento di Scienze Matematiche Fisiche e Informatiche Università di Parma 43124 Parma Italy
- INFN–Sezione di Milano-Bicocca Gruppo Collegato di Parma I-43124 Parma Italy
- UdR Parma INSTM I-43124 Parma Italy
| | - Richard E. P. Winpenny
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Alice M. Bowen
- National Research Facility for Electron Paramagnetic Resonance Spectroscopy Department of Chemistry and Photon Science Institute The University of Manchester Oxford Road Manchester M13 9PL UK
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10
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Rogers CJ, Asthana D, Brookfield A, Chiesa A, Timco GA, Collison D, Natrajan LS, Carretta S, Winpenny REP, Bowen AM. Modelling Conformational Flexibility in a Spectrally Addressable Molecular Multi-Qubit Model System. Angew Chem Int Ed Engl 2022; 61:e202207947. [PMID: 36222278 PMCID: PMC9828767 DOI: 10.1002/anie.202207947] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Indexed: 11/11/2022]
Abstract
Dipolar coupled multi-spin systems have the potential to be used as molecular qubits. Herein we report the synthesis of a molecular multi-qubit model system with three individually addressable, weakly interacting, spin 1 / 2 ${{ 1/2 }}$ centres of differing g-values. We use pulsed Electron Paramagnetic Resonance (EPR) techniques to characterise and separately address the individual electron spin qubits; CuII , Cr7 Ni ring and a nitroxide, to determine the strength of the inter-qubit dipolar interaction. Orientation selective Relaxation-Induced Dipolar Modulation Enhancement (os-RIDME) detecting across the CuII spectrum revealed a strongly correlated CuII -Cr7 Ni ring relationship; detecting on the nitroxide resonance measured both the nitroxide and CuII or nitroxide and Cr7 Ni ring correlations, with switchability of the interaction based on differing relaxation dynamics, indicating a handle for implementing EPR-based quantum information processing (QIP) algorithms.
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Affiliation(s)
- Ciarán J. Rogers
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK
| | - Deepak Asthana
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK,Department of ChemistryAshoka UniversitySonipatHaryanaIndia
| | - Adam Brookfield
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK
| | - Alessandro Chiesa
- Dipartimento di Scienze Matematiche Fisiche e InformaticheUniversità di Parma43124ParmaItaly,INFN–Sezione di Milano-BicoccaGruppo Collegato di ParmaI-43124ParmaItaly,UdR ParmaINSTMI-43124ParmaItaly
| | - Grigore A. Timco
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK
| | - David Collison
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK
| | - Louise S. Natrajan
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK
| | - Stefano Carretta
- Dipartimento di Scienze Matematiche Fisiche e InformaticheUniversità di Parma43124ParmaItaly,INFN–Sezione di Milano-BicoccaGruppo Collegato di ParmaI-43124ParmaItaly,UdR ParmaINSTMI-43124ParmaItaly
| | - Richard E. P. Winpenny
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK
| | - Alice M. Bowen
- National Research Facility for Electron Paramagnetic Resonance SpectroscopyDepartment of Chemistry and Photon Science InstituteThe University of ManchesterOxford RoadManchesterM13 9PLUK
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11
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Hofmann L, Mandato A, Saxena S, Ruthstein S. The use of EPR spectroscopy to study transcription mechanisms. Biophys Rev 2022; 14:1141-1159. [PMID: 36345280 PMCID: PMC9636360 DOI: 10.1007/s12551-022-01004-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 09/26/2022] [Indexed: 02/08/2023] Open
Abstract
Electron paramagnetic resonance (EPR) spectroscopy has become a promising structural biology tool to resolve complex and dynamic biological mechanisms in-vitro and in-cell. Here, we focus on the advantages of continuous wave (CW) and pulsed EPR distance measurements to resolve transcription processes and protein-DNA interaction. The wide range of spin-labeling approaches that can be used to follow structural changes in both protein and DNA render EPR a powerful method to study protein-DNA interactions and structure-function relationships in other macromolecular complexes. EPR-derived data goes well beyond static structural information and thus serves as the method of choice if dynamic insight is needed. Herein, we describe the conceptual details of the theory and the methodology and illustrate the use of EPR to study the protein-DNA interaction of the copper-sensitive transcription factor, CueR.
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Affiliation(s)
- L. Hofmann
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat-Gan, Israel
| | - A. Mandato
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA USA
| | - S. Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA USA
| | - S. Ruthstein
- Department of Chemistry and the Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat-Gan, Israel
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12
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Oranges M, Wort JL, Fukushima M, Fusco E, Ackermann K, Bode BE. Pulse Dipolar Electron Paramagnetic Resonance Spectroscopy Reveals Buffer-Modulated Cooperativity of Metal-Templated Protein Dimerization. J Phys Chem Lett 2022; 13:7847-7852. [PMID: 35976741 PMCID: PMC9421889 DOI: 10.1021/acs.jpclett.2c01719] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 08/10/2022] [Indexed: 05/26/2023]
Abstract
Self-assembly of protein monomers directed by metal ion coordination constitutes a promising strategy for designing supramolecular architectures complicated by the noncovalent interaction between monomers. Herein, two pulse dipolar electron paramagnetic resonance spectroscopy (PDS) techniques, pulse electron-electron double resonance and relaxation-induced dipolar modulation enhancement, were simultaneously employed to study the CuII-templated dimerization behavior of a model protein (Streptococcus sp. group G, protein G B1 domain) in both phosphate and Tris-HCl buffers. A cooperative binding model could simultaneously fit all data and demonstrate that the cooperativity of protein dimerization across α-helical double-histidine motifs in the presence of CuII is strongly modulated by the buffer, representing a platform for highly tunable buffer-switchable templated dimerization. Hence, PDS enriches the family of techniques for monitoring binding processes, supporting the development of novel strategies for bioengineering structures and stable architectures assembled by an initial metal-templated dimerization.
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Ackermann K, Wort JL, Bode BE. Pulse dipolar EPR for determining nanomolar binding affinities. Chem Commun (Camb) 2022; 58:8790-8793. [PMID: 35837993 PMCID: PMC9350988 DOI: 10.1039/d2cc02360a] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protein interaction studies often require very low concentrations and highly sensitive biophysical methods. Here, we demonstrate that pulse dipolar electron paramagnetic resonance spectroscopy allows measuring dissociation constants in the nanomolar range. This approach is appealing for concentration-limited biomolecular systems and medium-to-high-affinity binding studies, demonstrated here at 50 nanomolar protein concentration. CuII-nitroxide RIDME measurements at 100 nM protein concentration allow reliable extraction of dissociation constants and distances, while measurements at 50 nM protein concentration allow reliable extraction of dissociation constants only.![]()
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Affiliation(s)
- Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, Scotland, UK.
| | - Joshua L Wort
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, Scotland, UK.
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, Scotland, UK.
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Bogetti X, Hasanbasri Z, Hunter HR, Saxena S. An optimal acquisition scheme for Q-band EPR distance measurements using Cu 2+-based protein labels. Phys Chem Chem Phys 2022; 24:14727-14739. [PMID: 35574729 DOI: 10.1039/d2cp01032a] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recent advances in site-directed Cu2+ labeling of proteins and nucleic acids have added an attractive new methodology to measure the structure-function relationship in biomolecules. Despite the promise, accessing the higher sensitivity of Q-band Double Electron Electron Resonance (DEER) has been challenging for Cu2+ labels designed for proteins. Q-band DEER experiments on this label typically require many measurements at different magnetic fields, since the pulses can excite only a few orientations at a given magnetic field. Herein, we analyze such orientational effects through simulations and show that three DEER measurements, at strategically selected magnetic fields, are generally sufficient to acquire an orientational-averaged DEER time trace for this spin label at Q-band. The modeling results are experimentally verified on Cu2+ labeled human glutathione S-transferase (hGSTA1-1). The DEER distance distribution measured at the Q-band shows good agreement with the distance distribution sampled by molecular dynamics (MD) simulations and X-band experiments. The concordance of MD sampled distances and experimentally measured distances adds growing evidence that MD simulations can accurately predict distances for the Cu2+ labels, which remains a key bottleneck for the commonly used nitroxide label. In all, this minimal collection scheme reduces data collection time by as much as six-fold and is generally applicable to many octahedrally coordinated Cu2+ systems. Furthermore, the concepts presented here may be applied to other metals and pulsed EPR experiments.
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Affiliation(s)
- Xiaowei Bogetti
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
| | - Zikri Hasanbasri
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
| | - Hannah R Hunter
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, PA 15260, USA.
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A Low-Spin CoII/Nitroxide Complex for Distance Measurements at Q-Band Frequencies. MAGNETOCHEMISTRY 2022. [DOI: 10.3390/magnetochemistry8040043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pulse dipolar electron paramagnetic resonance spectroscopy (PDS) is continuously furthering the understanding of chemical and biological assemblies through distance measurements in the nanometer range. New paramagnets and pulse sequences can provide structural insights not accessible through other techniques. In the pursuit of alternative spin centers for PDS, we synthesized a low-spin CoII complex bearing a nitroxide (NO) moiety, where both the CoII and NO have an electron spin S of 1/2. We measured CoII-NO distances with the well-established double electron–electron resonance (DEER aka PELDOR) experiment, as well as with the five- and six-pulse relaxation-induced dipolar modulation enhancement (RIDME) spectroscopies at Q-band frequencies (34 GHz). We first identified challenges related to the stability of the complex in solution via DEER and X-ray crystallography and showed that even in cases where complex disproportionation is unavoidable, CoII-NO PDS measurements are feasible and give good signal-to-noise (SNR) ratios. Specifically, DEER and five-pulse RIDME exhibited an SNR of ~100, and while the six-pulse RIDME exhibited compromised SNR, it helped us minimize unwanted signals from the RIDME traces. Last, we demonstrated RIDME at a 10 μM sample concentration. Our results demonstrate paramagnetic CoII to be a feasible spin center in medium magnetic fields with opportunities for PDS studies involving CoII ions.
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Singewald K, Wilkinson JA, Saxena AS. Copper Based Site-directed Spin Labeling of Proteins for Use in Pulsed and Continuous Wave EPR Spectroscopy. Bio Protoc 2021; 11:e4258. [PMID: 35087917 DOI: 10.21769/bioprotoc.4258] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/08/2021] [Accepted: 10/13/2021] [Indexed: 11/02/2022] Open
Abstract
Site-directed spin labeling in conjunction with electron paramagnetic resonance (EPR) is an attractive approach to measure residue specific dynamics and point-to-point distance distributions in a biomolecule. Here, we focus on the labeling of proteins with a Cu(II)-nitrilotriacetic acid (NTA) complex, by exploiting two strategically placed histidine residues (called the dHis motif). This labeling strategy has emerged as a means to overcome key limitations of many spin labels. Through utilizing the dHis motif, Cu(II)NTA rigidly binds to a protein without depending on cysteine residues. This protocol outlines three major points: the synthesis of the Cu(II)NTA complex; the measurement of continuous wave and pulsed EPR spectra, to verify a successful synthesis, as well as successful protein labeling; and utilizing Cu(II)NTA labeled proteins, to measure distance constraints and backbone dynamics. In doing so, EPR measurements are less influenced by sidechain motion, which influences the breadth of the measured distance distributions between two spins, as well as the measured residue-specific dynamics. More broadly, such EPR-based distance measurements provide unique structural constraints for integrative structural biophysics and complement traditional biophysical techniques, such as NMR, cryo-EM, FRET, and crystallography. Graphic abstract: Monitoring the success of Cu(II)NTA labeling.
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Affiliation(s)
- Kevin Singewald
- Department of Chemistry, University of Pittsburgh, Pittsburgh, USA
| | | | - And Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, USA
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Ackermann K, Chapman A, Bode BE. A Comparison of Cysteine-Conjugated Nitroxide Spin Labels for Pulse Dipolar EPR Spectroscopy. Molecules 2021; 26:7534. [PMID: 34946616 PMCID: PMC8706713 DOI: 10.3390/molecules26247534] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/30/2021] [Accepted: 12/03/2021] [Indexed: 11/23/2022] Open
Abstract
The structure-function and materials paradigms drive research on the understanding of structures and structural heterogeneity of molecules and solids from materials science to structural biology. Functional insights into complex architectures are often gained from a suite of complementary physicochemical methods. In the context of biomacromolecular structures, the use of pulse dipolar electron paramagnetic resonance spectroscopy (PDS) has become increasingly popular. The main interest in PDS is providing long-range nanometre distance distributions that allow for identifying macromolecular topologies, validating structural models and conformational transitions as well as docking of quaternary complexes. Most commonly, cysteines are introduced into protein structures by site-directed mutagenesis and modified site-specifically to a spin-labelled side-chain such as a stable nitroxide radical. In this contribution, we investigate labelling by four different commercial labelling agents that react through different sulfur-specific reactions. Further, the distance distributions obtained are between spin-bearing moieties and need to be related to the protein structure via modelling approaches. Here, we compare two different approaches to modelling these distributions for all four side-chains. The results indicate that there are significant differences in the optimum labelling procedure. All four spin-labels show differences in the ease of labelling and purification. Further challenges arise from the different tether lengths and rotamers of spin-labelled side-chains; both influence the modelling and translation into structures. Our comparison indicates that the spin-label with the shortest tether in the spin-labelled side-group, (bis-(2,2,5,5-Tetramethyl-3-imidazoline-1-oxyl-4-yl) disulfide, may be underappreciated and could increase the resolution of structural studies by PDS if labelling conditions are optimised accordingly.
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Affiliation(s)
| | | | - Bela E. Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK; (K.A.); (A.C.)
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Ackermann K, Wort JL, Bode BE. Nanomolar Pulse Dipolar EPR Spectroscopy in Proteins: Cu II-Cu II and Nitroxide-Nitroxide Cases. J Phys Chem B 2021; 125:5358-5364. [PMID: 33998795 PMCID: PMC7611071 DOI: 10.1021/acs.jpcb.1c03666] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The study of ever more complex biomolecular assemblies implicated in human health and disease is facilitated by a suite of complementary biophysical methods. Pulse dipolar electron paramagnetic resonance spectroscopy (PDS) is a powerful tool that provides highly precise geometric constraints in frozen solutions; however, the drive toward PDS at physiologically relevant sub-μM concentrations is limited by the currently achievable concentration sensitivity. Recently, PDS using a combination of nitroxide- and CuII-based spin labels allowed measuring a 500 nM concentration of a model protein. Using commercial instrumentation and spin labels, we demonstrate CuII-CuII and nitroxide-nitroxide PDS measurements at protein concentrations below previous examples reaching 500 and 100 nM, respectively. These results demonstrate the general feasibility of sub-μM PDS measurements at short to intermediate distances (∼1.5 to 3.5 nm), and are of particular relevance for applications where the achievable concentration is limiting.
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Casto J, Mandato A, Saxena S. dHis-troying Barriers: Deuteration Provides a Pathway to Increase Sensitivity and Accessible Distances for Cu 2+ Labels. J Phys Chem Lett 2021; 12:4681-4685. [PMID: 33979151 DOI: 10.1021/acs.jpclett.1c01002] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Recently, site-directed Cu2+ labeling has emerged as an incisive biophysical tool to directly report on distance constraints that pertain to the structure, conformational transitions, and dynamics of proteins and nucleic acids. However, short phase memory times inherent to the Cu2+ labels limit measurable distances to 4-5 nm. In this work we systematically examine different methods to dampen electron-nuclear and electron-electron coupled interactions to decrease rapid relaxation. We show that using Cu2+ spin concentrations up to ca. 800 μM has an invariant effect on relaxation and that increasing the cryoprotectant concentration reduces contributions of solvent protons to relaxation. On the other hand, the deuteration of protein and solvent dramatically increases the duration of the dipolar modulated signal by over 6-fold to 32 μs. Based on this increase in signal longevity, distances up to 9 nm and beyond can potentially be measured with Cu2+ labels.
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Affiliation(s)
- Joshua Casto
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Alysia Mandato
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Sunil Saxena
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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