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Felsted RG, Graham TR, Zhao Y, Bazak JD, Nienhuis ET, Pauzauskie PJ, Joly AG, Pearce CI, Wang Z, Rosso KM. Anionic Effects on Concentrated Aqueous Lithium Ion Dynamics. J Phys Chem Lett 2024:5076-5087. [PMID: 38708887 DOI: 10.1021/acs.jpclett.4c00585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
The dynamics, orientational anisotropy, diffusivity, viscosity, and density were measured for concentrated lithium salt solutions, including lithium chloride (LiCl), lithium bromide (LiBr), lithium nitrite (LiNO2), and lithium nitrate (LiNO3), with methyl thiocyanate as an infrared vibrational probe molecule, using two-dimensional infrared spectroscopy (2D IR), nuclear magnetic resonance (NMR) spectroscopy, and viscometry. The 2D IR, NMR, and viscosity results show that LiNO2 exhibits longer correlation times, lower diffusivity, and nearly 4 times greater viscosity compared to those of the other lithium salt solutions of the same concentration, suggesting that nitrite anions may strongly facilitate structure formation via strengthening water-ion network interactions, directly impacting bulk solution properties at sufficiently high concentrations. Additionally, the LiNO2 and LiNO3 solutions show significantly weakened chemical interactions between the lithium cations and the methyl thiocyanate when compared with those of the lithium halide salts.
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Affiliation(s)
- Robert G Felsted
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Trent R Graham
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Yatong Zhao
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - J David Bazak
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Emily T Nienhuis
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Peter J Pauzauskie
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Materials Science and Engineering Department, University of Washington, Seattle, Washington 98195, United States
| | - Alan G Joly
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Carolyn I Pearce
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- Department of Crop and Soil Sciences, Washington State University, Pullman, Washington 99164, United States
| | - Zheming Wang
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Kevin M Rosso
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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Hume S, Hithell G, Greetham GM, Donaldson PM, Towrie M, Parker AW, Baker MJ, Hunt NT. Measuring proteins in H 2O with 2D-IR spectroscopy. Chem Sci 2019; 10:6448-6456. [PMID: 31341597 PMCID: PMC6611063 DOI: 10.1039/c9sc01590f] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 05/13/2019] [Indexed: 02/06/2023] Open
Abstract
The amide I infrared band of proteins is highly sensitive to secondary structure, but studies under physiological conditions are prevented by strong, overlapping water absorptions, motivating the widespread use of deuterated solutions. H/D exchange raises fundamental questions regarding the impact of increased mass on protein dynamics, while deuteration is impractical for biomedical or commercial applications of protein IR spectroscopy. We show that 2D-IR spectroscopy can avoid this problem because the 2D-IR amide I signature of proteins dominates that of water even at sub-millimolar protein concentrations. Using equine blood serum as a test system, we investigate the significant implications of being able to measure the spectroscopy and dynamics of proteins in water, demonstrating relevance in areas ranging from fundamental science to the clinic. Measurements of vibrational relaxation dynamics of serum proteins reveals that deuteration slows down the rate of amide I vibrational relaxation by >10%, indicating a dynamic impact of isotopic exchange in some proteins. The unique link between protein secondary structure and 2D-IR amide I lineshape allows differentiation of signals due to albumin and globulin protein fractions in serum leading to measurements of the biomedically-important albumin to globulin ratio (AGR) with an accuracy of ±4% across a clinically-relevant range. Furthermore, we demonstrate that 2D-IR spectroscopy enables differentiation of the structurally similar globulin proteins IgG, IgA and IgM, opening up a straightforward spectroscopic approach to measuring levels of serum proteins that are currently only accessible via biomedical laboratory testing.
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Affiliation(s)
- Samantha Hume
- Department of Physics , University of Strathclyde , SUPA , 107 Rottenrow East , Glasgow , G4 0NG , UK
| | - Gordon Hithell
- Department of Physics , University of Strathclyde , SUPA , 107 Rottenrow East , Glasgow , G4 0NG , UK
| | - Gregory M Greetham
- STFC Central Laser Facility , Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot , OX11 0QX , UK
| | - Paul M Donaldson
- STFC Central Laser Facility , Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot , OX11 0QX , UK
| | - Michael Towrie
- STFC Central Laser Facility , Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot , OX11 0QX , UK
| | - Anthony W Parker
- STFC Central Laser Facility , Research Complex at Harwell , Rutherford Appleton Laboratory , Harwell Campus , Didcot , OX11 0QX , UK
| | - Matthew J Baker
- WestCHEM , Department of Pure and Applied Chemistry , University of Strathclyde , Technology and Innovation Centre , 99 George Street , Glasgow , G1 1RD , UK
| | - Neil T Hunt
- Department of Chemistry , York Biomedical Research Institute , University of York , Heslington , York , YO10 5DD , UK .
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3
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Kiefer LM, Kubarych KJ. Two-dimensional infrared spectroscopy of coordination complexes: From solvent dynamics to photocatalysis. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Donaldson P, Greetham G, Shaw D, Parker A, Towrie M. A 100 kHz Pulse Shaping 2D-IR Spectrometer Based on Dual Yb:KGW Amplifiers. J Phys Chem A 2018; 122:780-787. [DOI: 10.1021/acs.jpca.7b10259] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- P.M. Donaldson
- Central
Laser Facility, Science and Technology Facilities Council, Research
Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - G.M. Greetham
- Central
Laser Facility, Science and Technology Facilities Council, Research
Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - D.J. Shaw
- Central
Laser Facility, Science and Technology Facilities Council, Research
Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
- Department
of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow, G4 0NG, U.K
| | - A.W. Parker
- Central
Laser Facility, Science and Technology Facilities Council, Research
Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
| | - M. Towrie
- Central
Laser Facility, Science and Technology Facilities Council, Research
Complex at Harwell, Rutherford Appleton Laboratory, Didcot, OX11 0QX, U.K
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5
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Hithell G, González-Jiménez M, Greetham GM, Donaldson PM, Towrie M, Parker AW, Burley GA, Wynne K, Hunt NT. Ultrafast 2D-IR and optical Kerr effect spectroscopy reveal the impact of duplex melting on the structural dynamics of DNA. Phys Chem Chem Phys 2017; 19:10333-10342. [DOI: 10.1039/c7cp00054e] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Changes in the structural and solvation dynamics of DNA upon duplex melting are observed by 2D-IR and optical Kerr-effect spectroscopies.
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Affiliation(s)
- Gordon Hithell
- Department of Physics, University of Strathclyde, SUPA
- Glasgow
- UK
| | | | - Gregory M. Greetham
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus
- Didcot
- UK
| | - Paul M. Donaldson
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus
- Didcot
- UK
| | - Michael Towrie
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus
- Didcot
- UK
| | - Anthony W. Parker
- STFC Central Laser Facility, Research Complex at Harwell, Harwell Science and Innovation Campus
- Didcot
- UK
| | - Glenn A. Burley
- Department of Pure and Applied Chemistry, WestCHEM, University of Strathclyde, 295 Cathedral Street
- Glasgow
- UK
| | - Klaas Wynne
- School of Chemistry, WestCHEM, University of Glasgow
- Glasgow
- UK
| | - Neil T. Hunt
- Department of Physics, University of Strathclyde, SUPA
- Glasgow
- UK
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Ultrafast Structural Fluctuations of Myoglobin-Bound Thiocyanate and Selenocyanate Ions Measured with Two-Dimensional Infrared Photon Echo Spectroscopy. Chemphyschem 2015; 16:3468-76. [DOI: 10.1002/cphc.201500606] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 08/27/2015] [Indexed: 11/07/2022]
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Abstract
Two-dimensional infrared (2D IR) spectroscopy has recently emerged as a powerful tool with applications in many areas of scientific research. The inherent high time resolution coupled with bond-specific spatial resolution of IR spectroscopy enable direct characterization of rapidly interconverting species and fast processes, even in complex systems found in chemistry and biology. In this minireview, we briefly outline the fundamental principles and experimental procedures of 2D IR spectroscopy. Using illustrative example studies, we explain the important features of 2D IR spectra and their capability to elucidate molecular structure and dynamics. Primarily, this minireview aims to convey the scope and potential of 2D IR spectroscopy by highlighting select examples of recent applications including the use of innate or introduced vibrational probes for the study of nucleic acids, peptides/proteins, and materials.
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Affiliation(s)
- Amanda L Le Sueur
- Department of Chemistry, Indiana University, Bloomington, Indiana, 47405, USA.
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Shaw DJ, Adamczyk K, Frederix PWJM, Simpson N, Robb K, Greetham GM, Towrie M, Parker AW, Hoskisson PA, Hunt NT. Multidimensional infrared spectroscopy reveals the vibrational and solvation dynamics of isoniazid. J Chem Phys 2015; 142:212401. [DOI: 10.1063/1.4914097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- Daniel J. Shaw
- Department of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow G4 0NG, United Kingdom
- Strathclyde Institute for Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, United Kingdom
| | - Katrin Adamczyk
- Department of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow G4 0NG, United Kingdom
| | - Pim W. J. M. Frederix
- Department of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow G4 0NG, United Kingdom
| | - Niall Simpson
- Department of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow G4 0NG, United Kingdom
| | - Kirsty Robb
- Strathclyde Institute for Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, United Kingdom
| | - Gregory M. Greetham
- STFC Rutherford Appleton Laboratory, Central Laser Facility, Research Complex at Harwell, Didcot OX11 0QX, United Kingdom
| | - Michael Towrie
- STFC Rutherford Appleton Laboratory, Central Laser Facility, Research Complex at Harwell, Didcot OX11 0QX, United Kingdom
| | - Anthony W. Parker
- STFC Rutherford Appleton Laboratory, Central Laser Facility, Research Complex at Harwell, Didcot OX11 0QX, United Kingdom
| | - Paul A. Hoskisson
- Strathclyde Institute for Pharmacy and Biomedical Sciences (SIPBS), University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, United Kingdom
| | - Neil T. Hunt
- Department of Physics, University of Strathclyde, SUPA, 107 Rottenrow East, Glasgow G4 0NG, United Kingdom
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Simpson N, Adamczyk K, Hithell G, Shaw DJ, Greetham GM, Towrie M, Parker AW, Hunt NT. The effect on structural and solvent water molecules of substrate binding to ferric horseradish peroxidase. Faraday Discuss 2015; 177:163-79. [DOI: 10.1039/c4fd00161c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ultrafast, multi-dimensional infrared spectroscopy, in the form of 2D-IR and pump–probe measurements, has been employed to investigate the effect of substrate binding on the structural dynamics of the horseradish peroxidase (HRP) enzyme. Using nitric oxide bound to the ferric haem of HRP as a sensitive probe of local dynamics, we report measurements of the frequency fluctuations (spectral diffusion) and vibrational lifetime of the NO stretching mode with benzohydroxamic acid (BHA) located in the substrate-binding position at the periphery of the haem pocket, in both D2O and H2O solvents. The results reveal that, with BHA bound to the enzyme, the local structural dynamics are insensitive to H/D exchange. These results are in stark contrast to those found in studies of the substrate-free enzyme, which demonstrated that the local chemical and dynamic environment of the haem ligand is influenced by water molecules. In light of the large changes in solvent accessibility caused by substrate binding, we discuss the potential for varying roles for the solvent in the haem pocket of HRP at different stages along the reaction coordinate of the enzymatic mechanism.
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Affiliation(s)
- Niall Simpson
- Department of Physics
- University of Strathclyde
- SUPA
- Glasgow
- UK
| | | | - Gordon Hithell
- Department of Physics
- University of Strathclyde
- SUPA
- Glasgow
- UK
| | - Daniel J. Shaw
- Department of Physics
- University of Strathclyde
- SUPA
- Glasgow
- UK
| | - Gregory M. Greetham
- Central Laser Facility, Research Complex at Harwell
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | - Michael Towrie
- Central Laser Facility, Research Complex at Harwell
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | - Anthony W. Parker
- Central Laser Facility, Research Complex at Harwell
- STFC Rutherford Appleton Laboratory
- Didcot
- UK
| | - Neil T. Hunt
- Department of Physics
- University of Strathclyde
- SUPA
- Glasgow
- UK
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11
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Lee C, Son H, Park S. Acid–base equilibrium dynamics in methanol and dimethyl sulfoxide probed by two-dimensional infrared spectroscopy. Phys Chem Chem Phys 2015; 17:17557-61. [DOI: 10.1039/c5cp02368h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two-dimensional infrared (2DIR) spectroscopy was successfully used to investigate the acid dissociation equilibrium of HN3 in methanol (CH3OH) and dimethyl sulfoxide (DMSO).
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Affiliation(s)
- Chiho Lee
- Department of Chemistry
- Korea University
- Seoul 136-701
- Korea
| | - Hyewon Son
- Department of Chemistry
- Korea University
- Seoul 136-701
- Korea
| | - Sungnam Park
- Department of Chemistry
- Korea University
- Seoul 136-701
- Korea
- Multidimensional Spectroscopy Laboratory
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12
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Adamczyk K, Simpson N, Greetham GM, Gumiero A, Walsh MA, Towrie M, Parker AW, Hunt NT. Ultrafast infrared spectroscopy reveals water-mediated coherent dynamics in an enzyme active site. Chem Sci 2014; 6:505-516. [PMID: 28936306 PMCID: PMC5588449 DOI: 10.1039/c4sc02752c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 10/22/2014] [Indexed: 11/24/2022] Open
Abstract
Ultrafast infrared spectroscopy provides insights into the dynamic nature of water in the active sites of catalase and peroxidase enzymes.
Understanding the impact of fast dynamics upon the chemical processes occurring within the active sites of proteins and enzymes is a key challenge that continues to attract significant interest, though direct experimental insight in the solution phase remains sparse. Similar gaps in our knowledge exist in understanding the role played by water, either as a solvent or as a structural/dynamic component of the active site. In order to investigate further the potential biological roles of water, we have employed ultrafast multidimensional infrared spectroscopy experiments that directly probe the structural and vibrational dynamics of NO bound to the ferric haem of the catalase enzyme from Corynebacterium glutamicum in both H2O and D2O. Despite catalases having what is believed to be a solvent-inaccessible active site, an isotopic dependence of the spectral diffusion and vibrational lifetime parameters of the NO stretching vibration are observed, indicating that water molecules interact directly with the haem ligand. Furthermore, IR pump–probe data feature oscillations originating from the preparation of a coherent superposition of low-frequency vibrational modes in the active site of catalase that are coupled to the haem ligand stretching vibration. Comparisons with an exemplar of the closely-related peroxidase enzyme family shows that they too exhibit solvent-dependent active-site dynamics, supporting the presence of interactions between the haem ligand and water molecules in the active sites of both catalases and peroxidases that may be linked to proton transfer events leading to the formation of the ferryl intermediate Compound I. In addition, a strong, water-mediated, hydrogen bonding structure is suggested to occur in catalase that is not replicated in peroxidase; an observation that may shed light on the origins of the different functions of the two enzymes.
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Affiliation(s)
- Katrin Adamczyk
- Department of Physics , University of Strathclyde , SUPA , 107 Rottenrow East , Glasgow , G4 0NG , UK .
| | - Niall Simpson
- Department of Physics , University of Strathclyde , SUPA , 107 Rottenrow East , Glasgow , G4 0NG , UK .
| | - Gregory M Greetham
- Central Laser Facility , Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford , Didcot, Oxon , OX11 0QX , UK
| | - Andrea Gumiero
- Diamond Light Source , Diamond House, Harwell Science and Innovation Campus , Didcot, Oxfordshire , OX11 0DE , UK
| | - Martin A Walsh
- Diamond Light Source , Diamond House, Harwell Science and Innovation Campus , Didcot, Oxfordshire , OX11 0DE , UK
| | - Michael Towrie
- Central Laser Facility , Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford , Didcot, Oxon , OX11 0QX , UK
| | - Anthony W Parker
- Central Laser Facility , Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford , Didcot, Oxon , OX11 0QX , UK
| | - Neil T Hunt
- Department of Physics , University of Strathclyde , SUPA , 107 Rottenrow East , Glasgow , G4 0NG , UK .
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Abstract
This Perspective discusses applications of ultrafast transient 2D-IR spectroscopy methods to the study of inorganic excited states.
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Affiliation(s)
- N. T. Hunt
- Department of Physics
- University of Strathclyde
- Glasgow, UK
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14
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Simpson N, Shaw DJ, Frederix PWJM, Gillies AH, Adamczyk K, Greetham GM, Towrie M, Parker AW, Hoskisson PA, Hunt NT. Infrared spectroscopy of nicotinamide adenine dinucleotides in one and two dimensions. J Phys Chem B 2013; 117:16468-78. [PMID: 24313706 DOI: 10.1021/jp411091f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The development of multidimensional spectroscopic tools capable of resolving site-specific information about proteins and enzymes in the solution phase is an important aid to our understanding of biomolecular mechanisms, structure, and dynamics. Nicotinamide adenine dinucleotide (NAD) is a common biological substrate and so offers significant potential as an intrinsic vibrational probe of protein-ligand interactions but its complex molecular structure and incompletely characterized infrared spectrum currently limit its usefulness. Here, we report the FTIR spectroscopy of the oxidized and reduced forms of NAD at a range of pD values that relate to the "folded" and "unfolded" forms of the molecules that exist in solution. Comparisons with structural analogs and the use of density functional theory simulations provide a full assignment of the observed modes and their complex pD dependencies. Finally, ultrafast two-dimensional infrared spectra of the oxidized and reduced forms of NAD are reported and their usefulness as biomolecular probes is discussed.
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Affiliation(s)
- Niall Simpson
- Department of Physics, University of Strathclyde , SUPA, 107 Rottenrow East, Glasgow G4 0NG, United Kingdom
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pH-dependent picosecond structural dynamics in the distal pocket of nitrophorin 4 investigated by 2D IR spectroscopy. J Phys Chem B 2013; 117:15804-11. [PMID: 23885811 DOI: 10.1021/jp407052a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrophorin 4 (NP4) belongs to a family of pH-sensitive, nitric oxide (NO) transporter proteins that undergo a large structural change from a closed to an open conformation at high pH to allow for NO delivery. Measuring the pH-dependent structural dynamics in NP4-NO around the ligand binding site is crucial for developing a mechanistic understanding of NO binding and release. In this study, we use coherent two-dimensional infrared (2D IR) spectroscopy to measure picosecond structural dynamics sampled by the nitrosyl stretch in NP4-NO as a function of pH at room temperature. Our results show that both the closed and open conformers of the protein are present at low (pD 5.1) and high (pD 7.9) pH conditions. The closed and open conformers are characterized by two frequencies of the nitrosyl stretching vibration labeled A0 and A1, respectively. Analysis of the 2D IR line shapes reveals that at pD 5.1, the closed conformer experiences structural fluctuations arising from solvation dynamics on a ∼3 ps time scale. At pD 7.9, both the open and closed conformers exhibit fluctuations on a ∼1 ps time scale. At both pD conditions, the closed conformers maintain a static distribution of structures within the experimental time window of 100 ps. This is in contrast to the open conformer, which is able to interconvert among its substates on a ∼100 ps time scale. Our results directly measure the time scales of solvation dynamics in the distal pocket, the flexibility of the open conformation at high pH, and the rigidity of the closed conformers at both pH conditions. We discuss how the pH-dependent equilibrium structural fluctuations of the nitrosyl ligand measured in this study are related to the uptake and delivery of nitric oxide in NP4.
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Brookes JF, Slenkamp KM, Lynch MS, Khalil M. Effect of solvent polarity on the vibrational dephasing dynamics of the nitrosyl stretch in an Fe(II) complex revealed by 2D IR spectroscopy. J Phys Chem A 2013; 117:6234-43. [PMID: 23480848 DOI: 10.1021/jp4005345] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The vibrational dephasing dynamics of the nitrosyl stretching vibration (ν(NO)) in sodium nitroprusside (SNP, Na2[Fe(CN)5NO]·2H2O) are investigated using two-dimensional infrared (2D IR) spectroscopy. The ν(NO) in SNP acts as a model system for the nitrosyl ligand found in metalloproteins which play an important role in the transportation and detection of nitric oxide (NO) in biological systems. We perform a 2D IR line shape study of the ν(NO) in the following solvents: water, deuterium oxide, methanol, ethanol, ethylene glycol, formamide, and dimethyl sulfoxide. The frequency of the ν(NO) exhibits a large vibrational solvatochromic shift of 52 cm(-1), ranging from 1884 cm(-1) in dimethyl sulfoxide to 1936 cm(-1) in water. The vibrational anharmonicity of the ν(NO) varies from 21 to 28 cm(-1) in the solvents used in this study. The frequency-frequency correlation functions (FFCFs) of the ν(NO) in SNP in each of the seven solvents are obtained by fitting the experimentally obtained 2D IR spectra using nonlinear response theory. The fits to the 2D IR line shape reveal that the spectral diffusion time scale of the ν(NO) in SNP varies from 0.8 to 4 ps and is negatively correlated with the empirical solvent polarity scales. We compare our results with the experimentally determined FFCFs of other charged vibrational probes in polar solvents and in the active sites of heme proteins. Our results suggest that the vibrational dephasing dynamics of the ν(NO) in SNP reflect the fluctuations of the nonhomogeneous electric field created by the polar solvents around the nitrosyl and cyanide ligands. The solute solvent interactions occurring at the trans-CN ligand are sensed through the π-back-bonding network along the Fe-NO bond in SNP.
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Affiliation(s)
- Jennifer F Brookes
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
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Glowacki DR, Lightfoot R, Harvey JN. Non-equilibrium phenomena and molecular reaction dynamics: mode space, energy space and conformer space. Mol Phys 2013. [DOI: 10.1080/00268976.2013.780100] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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18
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Candelaresi M, Gumiero A, Adamczyk K, Robb K, Bellota-Antón C, Sangal V, Munnoch J, Greetham GM, Towrie M, Hoskisson PA, Parker AW, Tucker NP, Walsh MA, Hunt NT. A structural and dynamic investigation of the inhibition of catalase by nitric oxide. Org Biomol Chem 2013; 11:7778-88. [DOI: 10.1039/c3ob41977k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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