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Qin XY, Zhang JT, Li GM, Cai MY, Lu J, Gu RZ, Liu WY. Selenium-chelating corn oligopeptide as a potential antioxidant supplement: investigation of the protein conformational changes and identification of the antioxidant fragment composition. INTERNATIONAL JOURNAL OF FOOD ENGINEERING 2020. [DOI: 10.1515/ijfe-2019-0166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
AbstractA selenium-chelating corn oligopeptide (Se-COP) with high protein and low molecular weight was prepared as a selenium supplement. We utilized infrared (IR), ultraviolet (UV), and circular dichroism (CD) spectroscopy, 1-anilinonaphthalene-8-sulfonate (ANS)-binding fluorescence spectra, and isothermal titration calorimetry (ITC) to analyze and describe Se-COP and its reactions. It was concluded that the chelation reaction was a spontaneous process driven by enthalpy and entropy, with ΔH=3.79 × 104 ± 4075 cal/mol, ΔS = 146 cal/mol, ΔG = –23356.30 ± 126.94 cal/mol, binding constant Ka = 1.18 × 104 ± 855 M–1, and binding site number n = 0.13 ± 0.0126, and described as coordination bonds forming and hydrophobic interaction, as well as protein conformational changes including secondary and tertiary hydrophobic structure. Se-COP had strong antioxidant capacity, and mass spectrometry (MS) was used to identify the antioxidant peptide fragment, which was characterized as LLPPY and quantified at 428.95 ng/mg. This study indicated that Se-COP prepared by chelation may be a Se supplement with antioxidant capacity that can be applied in functional foods or ingredients.
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Affiliation(s)
- Xiu-Yuan Qin
- Beijing Engineering Research Center of Protein and Functional Peptides, China National Research Institute of Food and Fermentation Industries Co. Ltd., Beijing 100015, People's Republic of China
| | - Jiang-Tao Zhang
- Beijing Engineering Research Center of Protein and Functional Peptides, China National Research Institute of Food and Fermentation Industries Co. Ltd., Beijing 100015, People's Republic of China
| | - Guo-Ming Li
- Beijing Engineering Research Center of Protein and Functional Peptides, China National Research Institute of Food and Fermentation Industries Co. Ltd., Beijing 100015, People's Republic of China
| | - Mu-Yi Cai
- Beijing Engineering Research Center of Protein and Functional Peptides, China National Research Institute of Food and Fermentation Industries Co. Ltd., Beijing 100015, People's Republic of China
| | - Jun Lu
- Beijing Engineering Research Center of Protein and Functional Peptides, China National Research Institute of Food and Fermentation Industries Co. Ltd., Beijing 100015, People's Republic of China
| | - Rui-Zeng Gu
- Beijing Engineering Research Center of Protein and Functional Peptides, China National Research Institute of Food and Fermentation Industries Co. Ltd., Beijing 100015, People's Republic of China
| | - Wen-Ying Liu
- Beijing Engineering Research Center of Protein and Functional Peptides, China National Research Institute of Food and Fermentation Industries Co. Ltd., Beijing 100015, People's Republic of China
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2
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Bull JN, Anstöter CS, Verlet JRR. Ultrafast valence to non-valence excited state dynamics in a common anionic chromophore. Nat Commun 2019; 10:5820. [PMID: 31862884 PMCID: PMC6925192 DOI: 10.1038/s41467-019-13819-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/27/2019] [Indexed: 12/19/2022] Open
Abstract
Non-valence states in neutral molecules (Rydberg states) have well-established roles and importance in photochemistry, however, considerably less is known about the role of non-valence states in photo-induced processes in anions. Here, femtosecond time-resolved photoelectron imaging is used to show that photoexcitation of the S1(ππ*) state of the methyl ester of deprotonated para-coumaric acid – a model chromophore for photoactive yellow protein (PYP) – leads to a bifurcation of the excited state wavepacket. One part remains on the S1(ππ*) state forming a twisted intermediate, whilst a second part leads to the formation of a non-valence (dipole-bound) state. Both populations eventually decay independently by vibrational autodetachment. Valence-to-non-valence internal conversion has hitherto not been observed in the intramolecular photophysics of an isolated anion, raising questions into how common such processes might be, given that many anionic chromophores have bright valence states near the detachment threshold. Photoactive biomolecules rely on chromophores whose photochemistry depends on the environment. Here, the excited state dynamics of a model for the anionic biochromophore in photoactive yellow protein is investigated by time-resolved photoelectron spectroscopy showing involvement of a non-valence state, and lack of E-Z isomerisation in the gas phase.
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Affiliation(s)
- James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich, NR4 7TJ, UK
| | - Cate S Anstöter
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK
| | - Jan R R Verlet
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK.
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Berbigier JF, Duarte LGTA, Perez JM, Mendes RA, Zapp E, Atvars TDZ, Dal-Bó AG, Rodembusch FS. Excited state intramolecular proton transfer process in benzazole fluorophores tailored by polymeric matrix: A combined theoretical and experimental study. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111710] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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4
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Affiliation(s)
- Alice Henley
- Department of Chemistry, University College London, London, UK
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Henley A, Patel AM, Parkes MA, Anderson JC, Fielding HH. Role of Photoisomerization on the Photodetachment of the Photoactive Yellow Protein Chromophore. J Phys Chem A 2018; 122:8222-8228. [PMID: 30234981 DOI: 10.1021/acs.jpca.8b07770] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photocycle of photoactive yellow protein (PYP) is initiated by a photoinduced trans-cis isomerization around a C═C bond in the chromophore that lies at the heart of the protein; however, in addition to the desired photochemical pathway, the chromophore can undergo competing electronic relaxation processes. Here we combine gas-phase anion photoelectron spectroscopy and quantum chemistry calculations to investigate how locking the C═C bond in the chromophore controls the competition between these electronic relaxation processes following photoexcitation in the range 400-310 nm. We find evidence to suggest that preventing trans-cis isomerization effectively turns off internal conversion to the ground electronic state and enhances electron emission from the first electronically excited state.
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Affiliation(s)
- Alice Henley
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - Anand M Patel
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - Michael A Parkes
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - James C Anderson
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
| | - Helen H Fielding
- Department of Chemistry , University College London , London WC1H 0AJ , United Kingdom
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Parkes MA, Crellin J, Henley A, Fielding HH. A photoelectron imaging and quantum chemistry study of the deprotonated indole anion. Phys Chem Chem Phys 2018; 20:15543-15549. [PMID: 29808860 DOI: 10.1039/c8cp01902a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Indole is an important molecular motif in many biological molecules and exists in its deprotonated anionic form in the cyan fluorescent protein, an analogue of green fluorescent protein. However, the electronic structure of the deprotonated indole anion has been relatively unexplored. Here, we use a combination of anion photoelectron velocity-map imaging measurements and quantum chemistry calculations to probe the electronic structure of the deprotonated indole anion. We report vertical detachment energies (VDEs) of 2.45 ± 0.05 eV and 3.20 ± 0.05 eV, respectively. The value for D0 is in agreement with recent high-resolution measurements whereas the value for D1 is a new measurement. We find that the first electronically excited singlet state of the anion, S1(ππ*), lies above the VDE and has shape resonance character with respect to the D0 detachment continuum and Feshbach resonance character with respect to the D1 continuum.
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Affiliation(s)
- Michael A Parkes
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
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Henley A, Diveky ME, Patel AM, Parkes MA, Anderson JC, Fielding HH. Electronic structure and dynamics of torsion-locked photoactive yellow protein chromophores. Phys Chem Chem Phys 2017; 19:31572-31580. [PMID: 29165495 DOI: 10.1039/c7cp06950b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photocycle of photoactive yellow protein (PYP) begins with small-scale torsional motions of the chromophore leading to large-scale movements of the protein scaffold triggering a biological response. The role of single-bond torsional molecular motions of the chromophore in the initial steps of the PYP photocycle are not fully understood. Here, we employ anion photoelectron spectroscopy measurements and quantum chemistry calculations to investigate the electronic relaxation dynamics following photoexcitation of four model chromophores, para-coumaric acid, its methyl ester, and two analogues with aliphatic bridges hindering torsional motions around the single bonds adjacent to the alkene group. Following direct photoexcitation of S1 at 400 nm, we find that both single bond rotations play a role in steering the PYP chromophore through the S1/S0 conical intersection but that rotation around the single bond between the alkene moiety and the phenoxide group is particularly important. Following photoexcitation of higher lying electronic states in the range 346-310 nm, we find that rotation around the single bond between the alkene and phenoxide groups also plays a key role in the electronic relaxation from higher lying states to the S1 state. These results have potential applications in tuning the photoresponse of photoactive proteins and materials with chromophores based on PYP.
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Affiliation(s)
- Alice Henley
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Matus E Diveky
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Anand M Patel
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Michael A Parkes
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - James C Anderson
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Helen H Fielding
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
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García-Prieto FF, Muñoz-Losa A, Fdez Galván I, Sánchez ML, Aguilar MA, Martín ME. QM/MM Study of Substituent and Solvent Effects on the Excited State Dynamics of the Photoactive Yellow Protein Chromophore. J Chem Theory Comput 2017; 13:737-748. [PMID: 28072537 DOI: 10.1021/acs.jctc.6b01069] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Substituent and solvent effects on the excited state dynamics of the Photoactive Yellow Protein chromophore are studied using the average solvent electrostatic potential from molecular dynamics (ASEP/MD) method. Four molecular models were considered: the ester and thioester derivatives of the p-coumaric acid anion and their methylated derivatives. We found that the solvent produces dramatic modifications on the free energy profile of the S1 state: 1) Two twisted structures that are minima in the gas phase could not be located in aqueous solution. 2) Conical intersections (CIs) associated with the rotation of the single bond adjacent to the phenyl group are found for the four derivatives in water solution but only for thio derivatives in the gas phase. 3) The relative stability of minima and CIs is reverted with respect to the gas phase values, affecting the prevalent de-excitation paths. As a consequence of these changes, three competitive de-excitation channels are open in aqueous solution: the fluorescence emission from a planar minimum on S1, the trans-cis photoisomerization through a CI that involves the rotation of the vinyl double bond, and the nonradiative, nonreactive, de-excitation through the CI associated with the rotation of the single bond adjacent to the phenyl group. In the gas phase, the minima are the structures with the lower energy, while in solution these are the conical intersections. In solution, the de-excitation prevalent path seems to be the photoisomerization for oxo compounds, while thio compounds return to the initial trans ground state without emission.
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Affiliation(s)
- Francisco F García-Prieto
- Área de Química Física, University of Extremadura , Avda. Elvas s/n, Edif. José Ma Viguera Lobo 3a planta, Badajoz, 06006 Spain
| | - Aurora Muñoz-Losa
- Área de Química Física, University of Extremadura , Avda. Elvas s/n, Edif. José Ma Viguera Lobo 3a planta, Badajoz, 06006 Spain
| | - Ignacio Fdez Galván
- Department of Chemistry-Ångström, The Theoretical Chemistry Programme, Uppsala University , Box 518, 751 20 Uppsala, Sweden
| | - M Luz Sánchez
- Área de Química Física, University of Extremadura , Avda. Elvas s/n, Edif. José Ma Viguera Lobo 3a planta, Badajoz, 06006 Spain
| | - Manuel A Aguilar
- Área de Química Física, University of Extremadura , Avda. Elvas s/n, Edif. José Ma Viguera Lobo 3a planta, Badajoz, 06006 Spain
| | - M Elena Martín
- Área de Química Física, University of Extremadura , Avda. Elvas s/n, Edif. José Ma Viguera Lobo 3a planta, Badajoz, 06006 Spain
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Parkes MA, Phillips C, Porter MJ, Fielding HH. Controlling electron emission from the photoactive yellow protein chromophore by substitution at the coumaric acid group. Phys Chem Chem Phys 2016; 18:10329-36. [PMID: 27025529 DOI: 10.1039/c6cp00565a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Understanding how the interactions between a chromophore and its surrounding protein control the function of a photoactive protein remains a challenge. Here, we present the results of photoelectron spectroscopy measurements and quantum chemistry calculations aimed at investigating how substitution at the coumaryl tail of the photoactive yellow protein chromophore controls competing relaxation pathways following photoexcitation of isolated chromophores in the gas phase with ultraviolet light in the range 350-315 nm. The photoelectron spectra are dominated by electrons resulting from direct detachment and fast detachment from the 2(1)ππ* state but also have a low electron kinetic energy component arising from autodetachment from lower lying electronically excited states or thermionic emission from the electronic ground state. We find that substituting the hydrogen atom of the carboxylic acid group with a methyl group lowers the threshold for electron detachment but has very little effect on the competition between the different relaxation pathways, whereas substituting with a thioester group raises the threshold for electron detachment and appears to 'turn off' the competing electron emission processes from lower lying electronically excited states. This has potential implications in terms of tuning the light-induced electron donor properties of photoactive yellow protein.
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Affiliation(s)
- Michael A Parkes
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK.
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García-Prieto FF, Muñoz-Losa A, Luz Sánchez M, Elena Martín M, Aguilar MA. Solvent effects on de-excitation channels in the p-coumaric acid methyl ester anion, an analogue of the photoactive yellow protein (PYP) chromophore. Phys Chem Chem Phys 2016; 18:27476-27485. [DOI: 10.1039/c6cp03541h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Environmental effects on the deactivation channels of the PYP chromophore in the gas phase and water solution are compared at the CASPT2//CASSCF/cc-pVDZ level.
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Affiliation(s)
| | - Aurora Muñoz-Losa
- Institute of Theoretical Chemistry
- Faculty of Chemistry
- University of Vienna
- A-1090 Vienna
- Austria
| | - M. Luz Sánchez
- Área de Química Física
- University of Extremadura
- 06006 Badajoz
- Spain
| | - M. Elena Martín
- Área de Química Física
- University of Extremadura
- 06006 Badajoz
- Spain
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Chang XP, Li CX, Xie BB, Cui G. Photoprotection Mechanism of p-Methoxy Methylcinnamate: A CASPT2 Study. J Phys Chem A 2015; 119:11488-97. [PMID: 26513466 DOI: 10.1021/acs.jpca.5b08434] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
p-Methoxy methylcinnamate (p-MMC) shares the same molecular skeleton with octyl methoxycinnamate sunscreen. It is recently found that adding one water to p-MMC can significantly enhance the photoprotection efficiency. However, the physical origin is elusive. Herein we have employed multireference complete active space self-consistent field (CASSCF) and multistate complete active-space second-order perturbation (MS-CASPT2) methods to scrutinize the photophysical and photochemical mechanism of p-MMC and its one-water complex p-MMC-W. Specifically, we optimize the stationary-point structures on the (1)ππ*, (1)nπ*, and S0 potential energy surfaces to locate the (1)ππ*/S0 and (1)ππ*/(1)nπ* conical intersections and to map (1)ππ* and (1)nπ* excited-state relaxation paths. On the basis of the results, we find that, for the trans p-MMC, the major (1)ππ* deactivation path is decaying to the dark (1)nπ* state via the in-plane (1)ππ*/(1)nπ* crossing point, which only need overcome a small barrier of 2.5 kcal/mol; the minor one is decaying to the S0 state via the (1)ππ*/S0 conical intersection induced by out-of-plane photoisomerization. For the cis p-MMC, these two decay paths are comparable (1)ππ* deactivation paths: one is decaying to the dark (1)nπ* state via the (1)ππ*/(1)nπ* crossing point, and the second is decaying to the ground state via the (1)ππ*/S0 conical intersection. One-water hydration stabilizes the (1)ππ* state and meanwhile destabilizes the (1)nπ* state. As a consequence, the (1)ππ* deactivation path to the dark (1)nπ* state is heavily inhibited. The related barriers are increased to 5.8 and 3.3 kcal/mol for the trans and cis p-MMC-W, respectively. In comparison, the barriers associated with the photoisomerization-induced (1)ππ* decay paths are reduced to 2.5 and 1.3 kcal/mol for the trans and cis p-MMC-W. Therefore, the (1)ππ* decay paths to the S0 state are dominant relaxation channels when adding one water molecule. Finally, the present work contributes a lot of knowledge to understanding the photoprotection mechanism of methylcinnamate derivatives.
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Affiliation(s)
- Xue-Ping Chang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China
| | - Chun-Xiang Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China
| | - Bin-Bin Xie
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China
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