1
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Zhou L, Feng RR, Zhang W, Gai F. Triple-Bond Vibrations: Emerging Applications in Energy and Biological Sciences. J Phys Chem Lett 2024; 15:187-200. [PMID: 38156972 DOI: 10.1021/acs.jpclett.3c02619] [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: 01/03/2024]
Abstract
Triple bonds, such as that formed between two carbon atoms (i.e., C≡C) or that formed between one carbon atom and one nitrogen atom (i.e., C≡N), afford unique chemical bonding and hence vibrational characteristics. As such, they are not only frequently used to construct molecules with tailored chemical and/or physical properties but also employed as vibrational probes to provide site-specific chemical and/or physical information at the molecular level. Herein, we offer our perspective on the emerging applications of various triple-bond vibrations in energy and biological sciences with a focus on C≡C and C≡N triple bonds.
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Affiliation(s)
- Liang Zhou
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
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2
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Hassani M, Mallon CJ, Monzy JN, Schmitz AJ, Brewer SH, Fenlon EE, Tucker MJ. Inhibition of vibrational energy flow within an aromatic scaffold via heavy atom effect. J Chem Phys 2023; 158:224201. [PMID: 37309893 PMCID: PMC10275622 DOI: 10.1063/5.0153760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 05/25/2023] [Indexed: 06/14/2023] Open
Abstract
The regulation of intramolecular vibrational energy redistribution (IVR) to influence energy flow within molecular scaffolds provides a way to steer fundamental processes of chemistry, such as chemical reactivity in proteins and design of molecular diodes. Using two-dimensional infrared (2D IR) spectroscopy, changes in the intensity of vibrational cross-peaks are often used to evaluate different energy transfer pathways present in small molecules. Previous 2D IR studies of para-azidobenzonitrile (PAB) demonstrated that several possible energy pathways from the N3 to the cyano-vibrational reporters were modulated by Fermi resonance, followed by energy relaxation into the solvent [Schmitz et al., J. Phys. Chem. A 123, 10571 (2019)]. In this work, the mechanisms of IVR were hindered via the introduction of a heavy atom, selenium, into the molecular scaffold. This effectively eliminated the energy transfer pathway and resulted in the dissipation of the energy into the bath and direct dipole-dipole coupling between the two vibrational reporters. Several structural variations of the aforementioned molecular scaffold were employed to assess how each interrupted the energy transfer pathways, and the evolution of 2D IR cross-peaks was measured to assess the changes in the energy flow. By eliminating the energy transfer pathways through isolation of specific vibrational transitions, through-space vibrational coupling between an azido (N3) and a selenocyanato (SeCN) probe is facilitated and observed for the first time. Thus, the rectification of this molecular circuitry is accomplished through the inhibition of energy flow using heavy atoms to suppress the anharmonic coupling and, instead, favor a vibrational coupling pathway.
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Affiliation(s)
- Majid Hassani
- Department of Chemistry, University of Nevada, Reno, Nevada 89557, USA
| | | | - Judith N. Monzy
- Department of Chemistry, Franklin & Marshall College, Lancaster, Pennsylvania 17604-3003, USA
| | - Andrew J. Schmitz
- Department of Chemistry, University of Nevada, Reno, Nevada 89557, USA
| | - Scott H. Brewer
- Department of Chemistry, Franklin & Marshall College, Lancaster, Pennsylvania 17604-3003, USA
| | - Edward E. Fenlon
- Department of Chemistry, Franklin & Marshall College, Lancaster, Pennsylvania 17604-3003, USA
| | - Matthew J. Tucker
- Department of Chemistry, University of Nevada, Reno, Nevada 89557, USA
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3
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Haldar T, Chatterjee S, Alam MN, Maity P, Bagchi S. Blue Fluorescence of Cyano-tryptophan Predicts Local Electrostatics and Hydrogen Bonding in Biomolecules. J Phys Chem B 2022; 126:10732-10740. [PMID: 36511763 DOI: 10.1021/acs.jpcb.2c05848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cyano-tryptophan is an unnatural fluorescent amino acid that emits in the visible region. Along with the structural similarity with tryptophan, the unique photophysical properties of this fluorophore make it an ideal probe for biophysical research. Herein, combining fluorescence spectroscopy, infrared spectroscopy, and molecular dynamics simulations, we show that the cyano-tryptophan's emission energy quantifies the underlying bond-specific noncovalent interactions in terms of the electric field. We further report the use of fluorophore's emission energy to predict its hydrogen bond characteristics. We demonstrate that combining experiments with molecular dynamics simulations can provide the hydrogen bonding status of the nitrile moiety. In addition, we report a method to differentiate between aqueous and nonaqueous hydrogen-bonding partners. Using a phenomenological approach, we demonstrate that the presence of the cyano-indole moiety is responsible for the distinct correlations between the fluorophore's emission and the electrostatic forces on the nitrile bond. As indole is a privileged scaffold for both native amino acids and nucleobases, cyano-indoles will have many multifaceted applications.
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Affiliation(s)
- Tapas Haldar
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
| | - Srijan Chatterjee
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
| | - Md Nirshad Alam
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
| | - Pradip Maity
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
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4
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Liu J, Feng RR, Zhou L, Gai F, Zhang W. Photoenhancement of the C≡N Stretching Vibration Intensity of Aromatic Nitriles. J Phys Chem Lett 2022; 13:9745-9751. [PMID: 36222647 DOI: 10.1021/acs.jpclett.2c02418] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The C≡N stretching vibration is a versatile infrared (IR) reporter that is useful for a wide range of applications. Aiming to further expand its spectroscopic utility, herein, we show that, using 4-cyanoindole and 4-cyano-7-azaindole as examples, photoexcitation can significantly shift the frequency (νCN) and enhance the molar extinction coefficient (εCN) of this vibrational mode of aromatic nitriles and that, for these indole derivatives, the enhancement factor can reach 13. Moreover, we find that while solvent relaxation at the excited electronic state(s) always leads to an increase in εCN, its effect on νCN depends on the solute and the solvent. Taken together, these results demonstrate that solvent relaxation can differently affect the local environment of the nitrile group and its conjugation with the indole ring and, more importantly, that the C≡N stretching vibration can serve as a sensitive IR probe of charge and electron transfer processes in which an aromatic nitrile is involved.
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Affiliation(s)
- Jingsong Liu
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Ran-Ran Feng
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Liang Zhou
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
| | - Feng Gai
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wenkai Zhang
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
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5
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Chen S, Liao M, Li X, Li R, Zhang J, Zhang Y, Peng T. Metal center regulation of the porphyrin unit in covalent organic polymers for boosting the photocatalytic CO 2 reduction activity. Catal Sci Technol 2022. [DOI: 10.1039/d2cy01473d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Regulating the porphyrin's metal center of metalloporphyrin(MPor)/Ru(ii)-pincer complex(RuN3) covalent organic polymers (COPs) effectively boosted the CO2 photoreduction by promoting charge separation and sacrificial electron donor oxidation.
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Affiliation(s)
- Shengtao Chen
- College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Wuhan University, Wuhan 430072, PR China
| | - Meijing Liao
- College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, PR China
| | - Xinming Li
- College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Wuhan University, Wuhan 430072, PR China
| | - Renjie Li
- College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Wuhan University, Wuhan 430072, PR China
| | - Jing Zhang
- College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Wuhan University, Wuhan 430072, PR China
| | - Yuexing Zhang
- College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, PR China
| | - Tianyou Peng
- College of Chemistry and Molecular Sciences, Engineering Research Center of Organosilicon Compounds & Materials, Wuhan University, Wuhan 430072, PR China
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6
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Zhang Q, Wang B, Zhang Y, Yang J, Deng B, Ding B, Zhong D. Probing Intermolecular Interactions of Amyloidogenic Fragments of SOD1 by Site-Specific Tryptophan and Its Noncanonical Derivative. J Phys Chem B 2021; 125:13088-13098. [PMID: 34812635 DOI: 10.1021/acs.jpcb.1c07175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Transient amyloid intermediates are likely to be cytotoxic and play an essential role in amyloid-associated neurodegenerative diseases. Characterization of their structural and dynamic evolution is the key to elucidating the molecular mechanism of amyloid formation. Here, combining circular dichroism (CD), exciton couplet theory, and Fourier transform infrared spectroscopy with site-specific tryptophan (Trp) and its noncanonical derivative 5-cyano-tryptochan (Trp5CN), we developed a method to monitor strand-to-strand tertiary and sheet-to-sheet quaternary interactions in the aggregation cascades of an amyloidogenic fragment from protein SOD128-38 (with the sequence KVKVWGSIKGL). We found that the exciton couplet generated from the Bb band of Trp can be used as a probe for side chain interactions. Its sensitivity can be further improved by four times with the incorporation of Trp5CN. We further observed a red-shift of ∼2 cm-1 and a broadening of ∼2 cm-1 in the IR band generated from the CN stretch during the aggregation, which we attributed to the transition from a corkscrew-like structure to a cross-linked intermediate phase. We show here that the integration of optical methods with unique aromatic side chain-related probes is able to elucidate amyloid intermolecular interactions and even capture elusive transient intermediates on and off the amyloid assembling pathway.
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Affiliation(s)
- Qin Zhang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bingyao Wang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yifei Zhang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jie Yang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bodan Deng
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bei Ding
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dongping Zhong
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.,Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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7
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Vinogradov I, Feng Y, Kumar SKK, Guo C, Udagawa NS, Ge NH. Ultrafast vibrational dynamics of the tyrosine ring mode and its application to enkephalin insertion into phospholipid membranes as probed by two-dimensional infrared spectroscopy. J Chem Phys 2021; 155:035102. [PMID: 34293882 DOI: 10.1063/5.0054428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Enkephalins are small opioid peptides whose binding conformations are catalyzed by phospholipid membranes. Binding to opioid receptors is determined by the orientation of tyrosine and phenylalanine side chains. In this work, we investigate the effects of different charged phospholipid headgroups on the insertion of the tyrosine side chain into a lipid bilayer using a combination of 2D IR spectroscopy, anharmonic DFT calculations, and third order response function modeling. The insertion is probed by using the ∼1515 cm-1 tyrosine ring breathing mode, which we found exhibits rich vibrational dynamics on the picosecond timescale. These dynamics include rapid intramolecular vibrational energy redistribution (IVR), where some of the energy ends up in a dark state that shows up as an anharmonically shifted combination band. The waiting-time dependent 2D IR spectra also show an unusual line shape distortion that affects the extraction of the frequency-frequency correlation function (FFCF), which is the dynamic observable of interest that reflects the tyrosine side chain's insertion into the lipid bilayer. We proposed three models to account for this distortion: a hot-state exchange model, a local environment dependent IVR model, and a coherence transfer model. A qualitative analysis of these models suggests that the local environment dependent IVR rate best explains the line shape distortion, while the coherence transfer model best reproduced the effects on the FFCF. Even with these complex dynamics, we found that the tyrosine ring mode's FFCF is qualitatively correlated with the degree of insertion expected from the different phospholipid headgroups.
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Affiliation(s)
- Ilya Vinogradov
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Yuan Feng
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - S K Karthick Kumar
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Chenxu Guo
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Nina Saki Udagawa
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
| | - Nien-Hui Ge
- Department of Chemistry, University of California at Irvine, Irvine, California 92697-2025, USA
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8
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Thielges MC. Transparent window 2D IR spectroscopy of proteins. J Chem Phys 2021; 155:040903. [PMID: 34340394 PMCID: PMC8302233 DOI: 10.1063/5.0052628] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/21/2021] [Indexed: 02/01/2023] Open
Abstract
Proteins are complex, heterogeneous macromolecules that exist as ensembles of interconverting states on a complex energy landscape. A complete, molecular-level understanding of their function requires experimental tools to characterize them with high spatial and temporal precision. Infrared (IR) spectroscopy has an inherently fast time scale that can capture all states and their dynamics with, in principle, bond-specific spatial resolution. Two-dimensional (2D) IR methods that provide richer information are becoming more routine but remain challenging to apply to proteins. Spectral congestion typically prevents selective investigation of native vibrations; however, the problem can be overcome by site-specific introduction of amino acid side chains that have vibrational groups with frequencies in the "transparent window" of protein spectra. This Perspective provides an overview of the history and recent progress in the development of transparent window 2D IR of proteins.
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Affiliation(s)
- Megan C. Thielges
- Department of Chemistry, Indiana University, Bloomington,
Indiana 47405, USA
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9
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Tumbic GW, Hossan MY, Thielges MC. Protein Dynamics by Two-Dimensional Infrared Spectroscopy. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2021; 14:299-321. [PMID: 34314221 PMCID: PMC8713465 DOI: 10.1146/annurev-anchem-091520-091009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Proteins function as ensembles of interconverting structures. The motions span from picosecond bond rotations to millisecond and longer subunit displacements. Characterization of functional dynamics on all spatial and temporal scales remains challenging experimentally. Two-dimensional infrared spectroscopy (2D IR) is maturing as a powerful approach for investigating proteins and their dynamics. We outline the advantages of IR spectroscopy, describe 2D IR and the information it provides, and introduce vibrational groups for protein analysis. We highlight example studies that illustrate the power and versatility of 2D IR for characterizing protein dynamics and conclude with a brief discussion of the outlook for biomolecular 2D IR.
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Affiliation(s)
- Goran W Tumbic
- Department of Chemistry, Indiana University, Bloomington, Indiana 47401, USA;
| | - Md Yeathad Hossan
- Department of Chemistry, Indiana University, Bloomington, Indiana 47401, USA;
| | - Megan C Thielges
- Department of Chemistry, Indiana University, Bloomington, Indiana 47401, USA;
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10
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Micikas RJ, Ahmed IA, Acharyya A, Smith AB, Gai F. Tuning the electronic transition energy of indole via substitution: application to identify tryptophan-based chromophores that absorb and emit visible light. Phys Chem Chem Phys 2021; 23:6433-6437. [PMID: 33710175 DOI: 10.1039/d0cp06710e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Fluorescent amino acids (FAAs) offer significant advantages over fluorescent proteins in applications where the fluorophore size needs to be limited or minimized. A long-sought goal in biological spectroscopy/microcopy is to develop visible FAAs by modifying the indole ring of tryptophan. Herein, we examine the absorption spectra of a library of 4-substituted indoles and find that the frequency of the absorption maximum correlates linearly with the global electrophilicity index of the substituent. This finding permits us to identify two promising candidates, 4-formyltryptophan (4CHO-Trp) and 4-nitrotryptophan (4NO2-Trp), both of which can be excited by visible light. Further fluorescence measurements indicate that while 4CHO-indole (and 4CHO-Trp) emits cyan fluorescence with a reasonably large quantum yield (ca. 0.22 in ethanol), 4NO2-indole is essentially non-fluorescent, suggesting that 4CHO-Trp (4NO2-Trp) could be useful as a fluorescence reporter (quencher). In addition, we present a simple method for synthesizing 4CHO-Trp.
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Affiliation(s)
- Robert J Micikas
- Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA.
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11
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Edington SC, Liu S, Baiz CR. Infrared spectroscopy probes ion binding geometries. Methods Enzymol 2021; 651:157-191. [PMID: 33888203 DOI: 10.1016/bs.mie.2020.12.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Infrared (IR) spectroscopy is a well-established technique for probing the structure, behavior, and surroundings of molecules in their native environments. Its characteristics-most specifically high structural sensitivity, ready applicability to aqueous samples, and broad availability-make it a valuable enzymological technique, particularly for the interrogation of ion binding sites. While IR spectroscopy of the "garden variety" (steady state at room temperature with wild-type proteins) is versatile and powerful in its own right, the combination of IR spectroscopy with specialized experimental schemes for leveraging ultrafast time resolution, protein labeling, and other enhancements further extends this utility. This book chapter provides the fundamental physical background and literature context essential for harnessing IR spectroscopy in the general context of enzymology with specific focus on interrogation of ion binding. Studies of lanthanide ions binding to calmodulin are highlighted as illustrative examples of this process. Appropriate sample preparation, data collection, and spectral interpretation are discussed from a detail-oriented and practical perspective with the goal of facilitating the reader's rapid progression from reading words in a book to collecting and analyzing their own data in the lab.
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Affiliation(s)
- Sean C Edington
- Department of Chemistry, Yale University, New Haven, CT, United States
| | - Stephanie Liu
- Department of Chemistry, The University of Texas at Austin, Austin, TX, United States
| | - Carlos R Baiz
- Department of Chemistry, The University of Texas at Austin, Austin, TX, United States.
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12
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Chalyavi F, Schmitz AJ, Fetto NR, Tucker MJ, Brewer SH, Fenlon EE. Extending the vibrational lifetime of azides with heavy atoms. Phys Chem Chem Phys 2020; 22:18007-18013. [PMID: 32749405 DOI: 10.1039/d0cp02814b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The development of novel vibrational reporters (VRs), aka infrared (IR) probes, to study local environments and dynamic processes in biomolecules and materials continues to be an important area of research. Azides are important VRs because of their small size and large transition dipole strengths, however, their relatively short vibrational lifetimes (<2 ps) have limited their full potential. Herein we report that the vibrational lifetimes of azides can be increased by attaching them to heavy atoms and by using heavy 15N isotopes. Three group 14 atom triphenyl azides (Ph3CN3, Ph3SiN3, Ph3SnN3), and their triple-15N isotopomers, were synthesized in good yields. Tributyltin azide and its heavy isotopomer (Bu3Sn15N3) were also prepared to probe the effect of molecular scaffolding. The extinction coefficients for the natural abundance azides were determined, ranging from 900 to 1500 M-1 cm-1. The vibrational lifetimes of all azides were measured by pump-probe IR spectroscopy and each showed a major component with a short-to-moderate vibrational lifetime and a minor component with a much longer vibrational lifetime. Based on these results, the lifetime, aka the observation window, of an azide reporter can be extended from ∼2 ps to as long as ∼300 ps by a combination of isotopic labeling and heavy atom effect. 2D IR measurements of these compounds further confirmed the ability to observe these azide transitions at much longer timescales showing their utility to capture dynamic processes from tens to hundreds of picoseconds.
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Affiliation(s)
- Farzaneh Chalyavi
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Andrew J Schmitz
- Department of Chemistry, University of Nevada at Reno, Reno, NV 89557, USA.
| | - Natalie R Fetto
- Department of Chemistry, University of Nevada at Reno, Reno, NV 89557, USA.
| | - Matthew J Tucker
- Department of Chemistry, University of Nevada at Reno, Reno, NV 89557, USA.
| | - Scott H Brewer
- Department of Chemistry, Franklin & Marshall College, Lancaster, PA 17604, USA. ,
| | - Edward E Fenlon
- Department of Chemistry, Franklin & Marshall College, Lancaster, PA 17604, USA. ,
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13
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Chalyavi F, Adeyiga O, Weiner JM, Monzy JN, Schmitz AJ, Nguyen JK, Fenlon EE, Brewer SH, Odoh SO, Tucker MJ. 2D-IR studies of cyanamides (NCN) as spectroscopic reporters of dynamics in biomolecules: Uncovering the origin of mysterious peaks. J Chem Phys 2020; 152:074201. [PMID: 32087671 PMCID: PMC7028433 DOI: 10.1063/1.5138654] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 01/27/2020] [Indexed: 12/17/2022] Open
Abstract
Cyanamides (NCN) have been shown to have a larger transition dipole strength than cyano-probes. In addition, they have similar structural characteristics and vibrational lifetimes to the azido-group, suggesting their utility as infrared (IR) spectroscopic reporters for structural dynamics in biomolecules. To access the efficacy of NCN as an IR probe to capture the changes in the local environment, several model systems were evaluated via 2D IR spectroscopy. Previous work by Cho [G. Lee, D. Kossowska, J. Lim, S. Kim, H. Han, K. Kwak, and M. Cho, J. Phys. Chem. B 122(14), 4035-4044 (2018)] showed that phenylalanine analogues containing NCN show strong anharmonic coupling that can complicate the interpretation of structural dynamics. However, when NCN is embedded in 5-membered ring scaffolds, as in N-cyanomaleimide and N-cyanosuccinimide, a unique band structure is observed in the 2D IR spectrum that is not predicted by simple anharmonic frequency calculations. Further investigation indicated that electron delocalization plays a role in the origins of the band structure. In particular, the origin of the lower frequency transitions is likely a result of direct interaction with the solvent.
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Affiliation(s)
- Farzaneh Chalyavi
- Department of Chemistry, University of Nevada Reno, Reno, Nevada 89557, USA
| | - Olajumoke Adeyiga
- Department of Chemistry, University of Nevada Reno, Reno, Nevada 89557, USA
| | - Julia M. Weiner
- Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17604-3003, USA
| | - Judith N. Monzy
- Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17604-3003, USA
| | - Andrew J. Schmitz
- Department of Chemistry, University of Nevada Reno, Reno, Nevada 89557, USA
| | - Justin K. Nguyen
- Department of Chemistry, University of Nevada Reno, Reno, Nevada 89557, USA
| | - Edward E. Fenlon
- Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17604-3003, USA
| | - Scott H. Brewer
- Department of Chemistry, Franklin and Marshall College, Lancaster, Pennsylvania 17604-3003, USA
| | - Samuel O. Odoh
- Department of Chemistry, University of Nevada Reno, Reno, Nevada 89557, USA
| | - Matthew J. Tucker
- Department of Chemistry, University of Nevada Reno, Reno, Nevada 89557, USA
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14
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Schmitz AJ, Pandey HD, Chalyavi F, Shi T, Fenlon EE, Brewer SH, Leitner DM, Tucker MJ. Tuning Molecular Vibrational Energy Flow within an Aromatic Scaffold via Anharmonic Coupling. J Phys Chem A 2019; 123:10571-10581. [PMID: 31735035 DOI: 10.1021/acs.jpca.9b08010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
From guiding chemical reactivity in synthesis or protein folding to the design of energy diodes, intramolecular vibrational energy redistribution harnesses the power to influence the underlying fundamental principles of chemistry. To evaluate the ability to steer these processes, the mechanism and time scales of intramolecular vibrational energy redistribution through aromatic molecular scaffolds have been assessed by utilizing two-dimensional infrared (2D IR) spectroscopy. 2D IR cross peaks reveal energy relaxation through an aromatic scaffold from the azido- to the cyano-vibrational reporters in para-azidobenzonitrile (PAB) and para-(azidomethyl)benzonitrile (PAMB) prior to energy relaxation into the solvent. The rates of energy transfer are modulated by Fermi resonances, which are apparent by the coupling cross peaks identified within the 2D IR spectrum. Theoretical vibrational mode analysis allowed the determination of the origins of the energy flow, the transfer pathway, and a direct comparison of the associated transfer rates, which were in good agreement with the experimental results. Large variations in energy-transfer rates, approximately 1.9 ps for PAB and 23 ps for PAMB, illustrate the importance of strong anharmonic coupling, i.e., Fermi resonance, on the transfer pathways. In particular, vibrational energy rectification is altered by Fermi resonances of the cyano- and azido-modes allowing control of the propensity for energy flow.
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Affiliation(s)
- Andrew J Schmitz
- Department of Chemistry , University of Nevada , Reno , Nevada 89557 , United States
| | - Hari Datt Pandey
- Department of Chemistry , University of California , Riverside , California 92521 , United States
| | - Farzaneh Chalyavi
- Department of Chemistry , University of Nevada , Reno , Nevada 89557 , United States
| | - Tianjiao Shi
- Department of Chemistry , Franklin & Marshall College , Lancaster , Pennsylvania 17604-3003 , United States
| | - Edward E Fenlon
- Department of Chemistry , Franklin & Marshall College , Lancaster , Pennsylvania 17604-3003 , United States
| | - Scott H Brewer
- Department of Chemistry , Franklin & Marshall College , Lancaster , Pennsylvania 17604-3003 , United States
| | - David M Leitner
- Department of Chemistry , University of Nevada , Reno , Nevada 89557 , United States
| | - Matthew J Tucker
- Department of Chemistry , University of Nevada , Reno , Nevada 89557 , United States
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15
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Zhang K, Ahmed IA, Kratochvil HT, DeGrado WF, Gai F, Jo H. Synthesis and application of the blue fluorescent amino acid l-4-cyanotryptophan to assess peptide-membrane interactions. Chem Commun (Camb) 2019; 55:5095-5098. [PMID: 30957824 PMCID: PMC6508085 DOI: 10.1039/c9cc01152h] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Recently, l-4-cyanotryptophan has been shown to be an efficient blue fluorescence emitter, with the potential to enable novel applications in biological spectroscopy and microscopy. However, lack of facile synthetic routes to this unnatural amino acid limits its wide use. Herein, we describe an expedient approach to synthesize Fmoc protected l-4-cyanotryptophan with high optical purity (>99%). Additionally, we test the utility of this blue fluorophore in imaging cell-membrane-bound peptides and in determining peptide-membrane binding constants.
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Affiliation(s)
- Kui Zhang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, United States
| | - Ismail A. Ahmed
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Huong T. Kratochvil
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, United States
| | - William F. DeGrado
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, United States
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Hyunil Jo
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, United States
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16
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Ramos S, Thielges MC. Site-Specific 1D and 2D IR Spectroscopy to Characterize the Conformations and Dynamics of Protein Molecular Recognition. J Phys Chem B 2019; 123:3551-3566. [PMID: 30848912 DOI: 10.1021/acs.jpcb.9b00969] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proteins exist as ensembles of interconverting states on a complex energy landscape. A complete, molecular-level understanding of their function requires knowledge of the populated states and thus the experimental tools to characterize them. Infrared (IR) spectroscopy has an inherently fast time scale that can capture all states and their dynamics with, in principle, bond-specific spatial resolution, and 2D IR methods that provide richer information are becoming more routine. Although application of IR spectroscopy for investigation of proteins is challenged by spectral congestion, the issue can be overcome by site-specific introduction of amino acid side chains that have IR probe groups with frequency-resolved absorptions, which furthermore enables selective characterization of different locations in proteins. Here, we briefly introduce the biophysical methods and summarize the current progress toward the study of proteins. We then describe our efforts to apply site-specific 1D and 2D IR spectroscopy toward elucidation of protein conformations and dynamics to investigate their involvement in protein molecular recognition, in particular mediated by dynamic complexes: plastocyanin and its binding partner cytochrome f, cytochrome P450s and substrates or redox partners, and Src homology 3 domains and proline-rich peptide motifs. We highlight the advantages of frequency-resolved probes to characterize specific, local sites in proteins and uncover variation among different locations, as well as the advantage of the fast time scale of IR spectroscopy to detect rapidly interconverting states. In addition, we illustrate the greater insight provided by 2D methods and discuss potential routes for further advancement of the field of biomolecular 2D IR spectroscopy.
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Affiliation(s)
- Sashary Ramos
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
| | - Megan C Thielges
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405 , United States
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17
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Verma PK, Kundu A, Cho M. How Molecular Crowding Differs from Macromolecular Crowding: A Femtosecond Mid-Infrared Pump-Probe Study. J Phys Chem Lett 2018; 9:6584-6592. [PMID: 30380875 DOI: 10.1021/acs.jpclett.8b03153] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Crowding is an inherent property of living systems in which biochemical processes occur in highly concentrated solutions of various finite-sized species of both low (molecular crowding) and high (macromolecular crowding) molecular weights. Is molecular crowding fundamentally different from macromolecular crowding? To answer this question, we use a femtosecond mid-infrared pump-probe technique with three vibrational probes in molecular (diethylene glycol) and macromolecular (polyethylene glycol) solutions. In less crowded media, both molecular and macromolecular crowders fail to affect the dynamics of interstitial bulk-like water molecules and those at the crowder/water interface. In highly crowded media, interstitial water dynamics strongly depends on molecular crowding, but macromolecular crowding does not alter the bulk-like hydration dynamics and has a modest crowding effect on water at the crowder/water interface. The results of this study provide a molecular level understanding of the structural and dynamic changes to water and the water-mediated cross-linking of crowders.
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Affiliation(s)
- Pramod Kumar Verma
- Center for Molecular Spectroscopy and Dynamics , Institute for Basic Science (IBS) , Seoul 02841 , Republic of Korea
- Department of Chemistry , Korea University , Seoul 02841 , Republic of Korea
- Department of Chemistry, Institute of Science , Banaras Hindu University , Varanasi 221005 , India
| | - Achintya Kundu
- Center for Molecular Spectroscopy and Dynamics , Institute for Basic Science (IBS) , Seoul 02841 , Republic of Korea
- Department of Chemistry , Korea University , Seoul 02841 , Republic of Korea
| | - Minhaeng Cho
- Center for Molecular Spectroscopy and Dynamics , Institute for Basic Science (IBS) , Seoul 02841 , Republic of Korea
- Department of Chemistry , Korea University , Seoul 02841 , Republic of Korea
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