1
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Liu MK, Li J, Li QS, Li ZS. Theoretical insights into photo-induced isomerization mechanisms of phenylsulfinyl radical PhSO˙. Phys Chem Chem Phys 2022; 24:6266-6273. [PMID: 35229842 DOI: 10.1039/d1cp05331k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sulfinyl radicals (R-SO˙) play important roles in lots of reactions, while the isomer oxathiyl radicals (R-OS˙) and the isomerization between them are rarely observed due to the poor stability of R-OS˙. In this work, the complete active space self-consistent field (CASSCF) and its multi-state second order perturbation (MS-CASPT2) methods were employed to study the photo-induced reaction mechanisms of phenylsulfinyl radical PhSO˙ 1 and its isomer phenoxathiyl radical PhOS˙ 2. Our results show that 1 and 2 have similar singly occupied molecular orbitals in the ground state but different properties in the excited state, which determine their diverse behaviors after irradiation. Radical 1 can generate 2 by light irradiation, but 2 produces isomerization product 3 (2-hydroxyphenylthiyl radical) and ring-opening product 4 (acyclic thioketoketene radical) in two paths via S atom migration intermediate Int1 (2-carbonylcyclohexadienthiyl radical). The former path involves consequent hydrogen shift reactions with a strongly exothermic process while the latter path involves both ring-expansion and ring-opening processes with a high barrier, resulting in a structural and energetic preference for the former path. Moreover, we revealed several conical intersections that participate in the reactions and facilitate the photochemical processes. Our calculations not only remain consistent with and clarify the experimental observations (X. Zeng, et al., J. Am. Chem. Soc., 2018, 140(31), 9972-9978) but also enrich the knowledge of sulfinyl radicals and isomer oxathiyl radicals.
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Affiliation(s)
- Meng-Kai Liu
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
| | - Jian Li
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
| | - Quan-Song Li
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
| | - Ze-Sheng Li
- Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China.
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2
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Zhang Z, Wang X, Sivaguru P, Wang Z. Exploring the synthetic application of sulfinyl radicals. Org Chem Front 2022. [DOI: 10.1039/d2qo01403c] [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
This review summarized the applications of sulfinyl radicals in organic chemistry and thoroughly examined the challenges and future development trends of sulfinyl radicals in modern organic chemistry, as well as their structures and properties.
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Affiliation(s)
- Zixu Zhang
- College of Chemistry and Environmental Science, Hebei University, Baoding, China
| | - Xinru Wang
- School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun, China
| | - Paramasivam Sivaguru
- Department of Research and Innovation, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai, Tamil Nadu, India
| | - Zikun Wang
- College of Chemistry and Environmental Science, Hebei University, Baoding, China
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3
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Two-step reaction mechanism reveals new antioxidant capability of cysteine disulfides against hydroxyl radical attack. Proc Natl Acad Sci U S A 2020; 117:18216-18223. [PMID: 32680962 DOI: 10.1073/pnas.2006639117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cysteine disulfides, which constitute an important component in biological redox buffer systems, are highly reactive toward the hydroxyl radical (•OH). The mechanistic details of this reaction, however, remain unclear, largely due to the difficulty in characterizing unstable reaction products. Herein, we have developed a combined approach involving mass spectrometry (MS) and theoretical calculations to investigate reactions of •OH with cysteine disulfides (Cys-S-S-R) in the gas phase. Four types of first-generation products were identified: protonated ions of the cysteine thiyl radical (+Cys-S•), cysteine (+Cys-SH), cysteine sulfinyl radical (+Cys-SO•), and cysteine sulfenic acid (+Cys-SOH). The relative reaction rates and product branching ratios responded sensitively to the electronic property of the R group, providing key evidence to deriving a two-step reaction mechanism. The first step involved •OH conducting a back-side attack on one of the sulfur atoms, forming sulfenic acid (-SOH) and thiyl radical (-S•) product pairs. A subsequent H transfer step within the product complex was favored for protonated systems, generating sulfinyl radical (-SO•) and thiol (-SH) products. Because sulfenic acid is a potent scavenger of peroxyl radicals, our results implied that cysteine disulfide can form two lines of defense against reactive oxygen species, one using the cysteine disulfide itself and the other using the sulfenic acid product of the conversion of cysteine disulfide. This aspect suggested that, in a nonpolar environment, cysteine disulfides might play a more active role in the antioxidant network than previously appreciated.
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4
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Lee JU, Kim Y, Kim WY, Oh HB. Graph theory-based reaction pathway searches and DFT calculations for the mechanism studies of free radical-initiated peptide sequencing mass spectrometry (FRIPS MS): a model gas-phase reaction of GGR tri-peptide. Phys Chem Chem Phys 2020; 22:5057-5069. [PMID: 32073000 DOI: 10.1039/c9cp05433b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Graph theory-based reaction pathway searches (ACE-Reaction program) and density functional theory calculations were performed to shed light on the mechanisms for the production of [an + H]+, xn+, yn+, zn+, and [yn + 2H]+ fragments formed in free radical-initiated peptide sequencing (FRIPS) mass spectrometry measurements of a small model system of glycine-glycine-arginine (GGR). In particular, the graph theory-based searches, which are rarely applied to gas-phase reaction studies, allowed us to investigate reaction mechanisms in an exhaustive manner without resorting to chemical intuition. As expected, radical-driven reaction pathways were favorable over charge-driven reaction pathways in terms of kinetics and thermodynamics. Charge- and radical-driven pathways for the formation of [yn + 2H]+ fragments were carefully compared, and it was revealed that the [yn + 2H]+ fragments observed in our FRIPS MS spectra originated from the radical-driven pathway, which is in contrast to the general expectation. The acquired understanding of the FRIPS fragmentation mechanism is expected to aid in the interpretation of FRIPS MS spectra. It should be emphasized that graph theory-based searches are powerful and effective methods for studying reaction mechanisms, including gas-phase reactions in mass spectrometry.
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Affiliation(s)
- Jae-Ung Lee
- Department of Chemistry, Sogang University, Seoul 04107, Republic of Korea.
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5
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Xu J, Wu Z, Wan H, Deng G, Lu B, Eckhardt AK, Schreiner PR, Trabelsi T, Francisco JS, Zeng X. Phenylsulfinyl Radical: Gas-Phase Generation, Photoisomerization, and Oxidation. J Am Chem Soc 2018; 140:9972-9978. [PMID: 29989805 DOI: 10.1021/jacs.8b05055] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Jian Xu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Zhuang Wu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Huabin Wan
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Guohai Deng
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Bo Lu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - André K. Eckhardt
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Peter R. Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Tarek Trabelsi
- University of Nebraska − Lincoln, Lincoln, Nebraska 68526, United States
| | - Joseph S. Francisco
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Xiaoqing Zeng
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
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6
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Wu Z, Xu J, Deng G, Chu X, Sokolenko L, Trabelsi T, Francisco JS, Eckhardt AK, Schreiner PR, Zeng X. The Trifluoromethyl Sulfinyl and Oxathiyl Radicals. Chemistry 2017; 24:1505-1508. [DOI: 10.1002/chem.201705142] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Zhuang Wu
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 P.R. China
| | - Jian Xu
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 P.R. China
| | - Guohai Deng
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 P.R. China
| | - Xianxu Chu
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 P.R. China
| | - Liubov Sokolenko
- Organofluorine Chemistry Department, Institute of Organic Chemistry; National Academy of Sciences of Ukraine; Kiev-94 02660 Ukraine
| | - Tarek Trabelsi
- University of Nebraska-Lincoln; Lincoln Nebraska 68526 USA
| | - Joseph S. Francisco
- Department of Chemistry; Purdue University; West Lafayette Indiana 47907 USA
| | - André K. Eckhardt
- Institute of Organic Chemistry; Justus-Liebig University; Heinrich-Buff-Ring 17 35392 Giessen Germany
| | - Peter R. Schreiner
- Institute of Organic Chemistry; Justus-Liebig University; Heinrich-Buff-Ring 17 35392 Giessen Germany
| | - Xiaoqing Zeng
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 P.R. China
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7
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Wu Z, Xu J, Sokolenko L, Yagupolskii YL, Feng R, Liu Q, Lu Y, Zhao L, Fernández I, Frenking G, Trabelsi T, Francisco JS, Zeng X. Parent Thioketene S-Oxide H2
CCSO: Gas-Phase Generation, Structure, and Bonding Analysis. Chemistry 2017; 23:16566-16573. [DOI: 10.1002/chem.201703161] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 09/04/2017] [Indexed: 01/03/2023]
Affiliation(s)
- Zhuang Wu
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 China
| | - Jian Xu
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 China
| | - Liubov Sokolenko
- Organofluorine Chemistry Department, Institute of Organic Chemistry; National Academy of Sciences of (Ukraine); Murmanskaya str. 5 02660 Kiev-94 Ukraine
| | - Yurii L. Yagupolskii
- Organofluorine Chemistry Department, Institute of Organic Chemistry; National Academy of Sciences of (Ukraine); Murmanskaya str. 5 02660 Kiev-94 Ukraine
| | - Ruijuan Feng
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 China
| | - Qian Liu
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 China
| | - Yan Lu
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 China
| | - Lili Zhao
- Institute of Advanced Synthesis; School of Chemistry and Molecular Engineering; Jiangsu National Synergetic Innovation Center for Advanced Materials; Nanjing Tech University; Nanjing 211816 China
| | - Israel Fernández
- Departamento de Química Orgánica I and Centro de Innovación en Química Avanzada; Facultad de Ciencias Químicas; Universidad Complutense de Madrid; 28040 Madrid Spain
| | - Gernot Frenking
- Institute of Advanced Synthesis; School of Chemistry and Molecular Engineering; Jiangsu National Synergetic Innovation Center for Advanced Materials; Nanjing Tech University; Nanjing 211816 China
- Fachbereich Chemie; Philipps-Universität Marburg; Marburg 35032 Germany
- Donostia International Physics Center (DIPC); P.K. 1072 20080 Donostia-San Sebastian Spain
| | - Tarek Trabelsi
- University of Nebraska-Lincoln; Lincoln Nebraska 68526 USA
| | - Joseph S. Francisco
- Department of Chemistry; Purdue University; West Lafayette Indiana 47907 USA
| | - Xiaoqing Zeng
- College of Chemistry, Chemical Engineering and Materials Science; Soochow University; Suzhou 215123 China
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8
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Mu X, Lau JKC, Lai CK, Siu KWM, Hopkinson AC, Chu IK. Isomerization versus dissociation of phenylalanylglycyltryptophan radical cations. Phys Chem Chem Phys 2017. [PMID: 28631796 DOI: 10.1039/c7cp02355c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Four isomers of the radical cation of tripeptide phenylalanylglycyltryptophan, in which the initial location of the radical center is well defined, have been isolated and their collision-induced dissociation (CID) spectra examined. These ions, the π-centered [FGWπ˙]+, α-carbon- [FGα˙W]+, N-centered [FGWN˙]+ and ζ-carbon- [Fζ˙GW]+ radical cations, were generated via collision-induced dissociation (CID) of transition metal-ligand-peptide complexes, side chain fragmentation of a π-centered radical cation, homolytic cleavage of a labile nitrogen-nitrogen single bond, and laser induced dissociation of an iodinated peptide, respectively. The π-centered and tryptophan N-centered peptide radical cations produced almost identical CID spectra, despite the different locations of their initial radical sites, which indicated that interconversion between the π-centered and tryptophan N-centered radical cations is facile. By contrast, the α-carbon-glycyl radical [FGα˙W]+, and ζ-phenyl radical [Fζ˙GW]+, featured different dissociation product ions, suggesting that the interconversions among α-carbon, π-centered (or tryptophan N-centered) and ζ-carbon-radical cations have higher barriers than those to dissociation. Density functional theory calculations have been used to perform systematic mechanistic investigations on the interconversions between these isomers and to study selected fragmentation pathways for these isomeric peptide radical cations. The results showed that the energy barrier for interconversion between [FGWπ˙]+ and [FGWN˙]+ is only 31.1 kcal mol-1, much lower than the barriers to their dissociation (40.3 kcal mol-1). For the [FGWπ˙]+, [FGα˙W]+, and [Fζ˙GW]+, the barriers to interconversion are higher than those to dissociation, suggesting that interconversions among these isomers are not competitive with dissociations. The [z3 - H]˙+ ions isolated from [FGα˙W]+ and [Fζ˙GW]+ show distinctly different fragmentation patterns, indicating that the structures of these ions are different and this result is supported by the DFT calculations.
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Affiliation(s)
- Xiaoyan Mu
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
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9
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Mu X, Song T, Siu CK, Chu IK. Tautomerization and Dissociation of Molecular Peptide Radical Cations. CHEM REC 2017. [DOI: 10.1002/tcr.201700013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Xiaoyan Mu
- Department of Chemistry; University of Hong Kong; Pokfulam, Hong Kong SAR P. R. China
| | - Tao Song
- Department of Chemistry; University of Hong Kong; Pokfulam, Hong Kong SAR P. R. China
| | - Chi-Kit Siu
- Department of Biology and Chemistry; City University of Hong Kong; 83 Tat Chee Avenue Kowloon Tong, Hong Kong SAR P. R. China
| | - Ivan K. Chu
- Department of Chemistry; University of Hong Kong; Pokfulam, Hong Kong SAR P. R. China
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10
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Hitzenberger JF, Dral PO, Meinhardt U, Clark T, Thiel W, Kivala M, Drewello T. Stability of Odd- Versus Even-Electron Gas-Phase (Quasi)Molecular Ions Derived from Pyridine-Substituted N-Heterotriangulenes. Chempluschem 2017; 82:204-211. [PMID: 31961553 DOI: 10.1002/cplu.201600416] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 10/11/2016] [Indexed: 11/08/2022]
Abstract
Electrospray ionisation of N-heterotriangulenes (i.e., dimethylmethylene-bridged triphenylamines) with up to three pyridyl groups at their periphery, produces the true radical cation ([M]+ . ) and the protonated molecule ([M+H]+ ) simultaneously. These ions are studied as model systems to illustrate the stability alternation of odd- versus even-electron ions in energy-dependent collision-induced dissociation (CID) experiments. All ions show the same fragmentation pattern, the consecutive loss of three methyl radicals (. CH3 ) from the dimethylmethylene bridges of the central triangulene core. [M]+ . ions dissociate at much lower collision energies than their [M+H]+ counterparts. The radical cation forms a singlet fragment with an extended aromatic system that is energetically favoured. Ab initio and density functional theory calculations support this interpretation and allow the assignment of the electronic structure of the fragment ions. Consecutive collision-induced dissociations provide a better match with theory when studied with an ion trap, rather than a linear quadrupole. This is attributed to the resonant nature of the excitation of intermediate ions.
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Affiliation(s)
- Jakob F Hitzenberger
- Physical Chemistry I, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse 3, 91058, Erlangen, Germany
| | - Pavlo O Dral
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Ute Meinhardt
- Organic Chemistry I, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Henkestrasse 42, 91054, Erlangen, Germany
| | - Timothy Clark
- Computer-Chemie-Centrum, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Nägelbachstrasse 25, 91052, Erlangen, Germany
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Milan Kivala
- Organic Chemistry I, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Henkestrasse 42, 91054, Erlangen, Germany
| | - Thomas Drewello
- Physical Chemistry I, Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Egerlandstrasse 3, 91058, Erlangen, Germany
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11
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Scuderi D, Bodo E, Chiavarino B, Fornarini S, Crestoni ME. Amino Acid Oxidation: A Combined Study of Cysteine Oxo Forms by IRMPD Spectroscopy and Simulations. Chemistry 2016; 22:17239-17250. [PMID: 27808437 DOI: 10.1002/chem.201603298] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Indexed: 01/02/2023]
Abstract
The redox activity of cysteine sulfur allows numerous post-translational protein modifications involved in the oxidative regulation of metabolism, in metal binding, and in signal transduction. A combined approach based on infrared multiple photon dissociation spectroscopy at the Centre Laser Infrarouge d'Orsay (CLIO) free electron laser facility, calculations of IR frequencies, and finite temperature ab initio molecular dynamics simulations has been employed to characterize the gas-phase structures of deprotonated cysteine sulfenic, sulfinic, and sulfonic acids, [cysSOx ]- (x=1, 2, 3, representing the number of S-bound oxygen atoms), which are key intermediates in the redox-switching chemistry of proteins. The ions show different structural motifs owing to preferential binding of the proton to either the carboxylate or sulfur-containing group. Due to the decreasing basicity of the sulfenic, sulfinic, and sulfonic terminals, the proton bound to SO- in [cysSO]- migrates to the carboxylate in [cysSO3 ]- , whereas it turns out to be shared in [cysSO2 ]- . Evidence is gathered that a mixture of close-lying low-energy conformers is sampled for each cysteine oxo form in a Paul ion trap at room temperature.
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Affiliation(s)
- Debora Scuderi
- Laboratoire de Chimie Physique d'Orsay, Faculté des Sciences, Université Paris Sud, UMR8000 CNRS, Bât 350, 91405, Orsay Cedex, France
| | - Enrico Bodo
- Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, P.le A. Moro 5, 00185, Roma, Italy
| | - Barbara Chiavarino
- Dipartimento di Chimica e Tecnologie del Farmaco, Università degli Studi di Roma La Sapienza, P.le A. Moro 5, 00185, Roma, Italy
| | - Simonetta Fornarini
- Dipartimento di Chimica e Tecnologie del Farmaco, Università degli Studi di Roma La Sapienza, P.le A. Moro 5, 00185, Roma, Italy
| | - Maria Elisa Crestoni
- Dipartimento di Chimica e Tecnologie del Farmaco, Università degli Studi di Roma La Sapienza, P.le A. Moro 5, 00185, Roma, Italy
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Love-Nkansah CB, Tan L, Francisco JS, Xia Y. Gas-Phase Unimolecular Dissociation Reveals Dominant Base Property of Protonated Homocysteine Sulfinyl Radical Ions. Chemistry 2015; 22:934-40. [PMID: 26531146 DOI: 10.1002/chem.201502642] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 11/12/2022]
Affiliation(s)
| | - Lei Tan
- Department of Chemistry; Purdue University; West Lafayette IN 47907-2084 USA
| | - Joseph S. Francisco
- Department of Chemistry and Department of Earth, Atmospheric, Planetary Sciences; Purdue University; West Lafayette IN 47907-2084 USA
| | - Yu Xia
- Department of Chemistry; Purdue University; West Lafayette IN 47907-2084 USA
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14
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Cai Y, Zheng Q, Liu Y, Helmy R, Loo JA, Chen H. Integration of electrochemistry with ultra-performance liquid chromatography/mass spectrometry. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2015; 21:341-51. [PMID: 26307715 PMCID: PMC4552337 DOI: 10.1255/ejms.1318] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This study presents the development of ultra-performance liquid chromatography (UPLC) mass spectrometry (MS) combined with electrochemistry (EC) for the first time and its application for the structural analysis of proteins/peptides that contain disulfide bonds. In our approach, a protein/peptide mixture sample undergoes a fast UPLC separation and subsequent electrochemical reduction in an electrochemical flow cell followed by online MS and tandem mass spectrometry (MS/MS) analyses. The electrochemical cell is coupled to the mass spectrometer using our recently developed desorption electrospray ionization (DESI) interface. Using this UPLC/EC/DESI-MS method, peptides that contain disulfide bonds can be differentiated from those without disulfide bonds, as the former are electroactive and reducible. MS/MS analysis of the disulfide-reduced peptide ions provides increased information on the sequence and disulfide-linkage pattern. In a reactive DESI- MS detection experiment in which a supercharging reagent was used to dope the DESI spray solvent, increased charging was obtained for the UPLC-separated proteins. Strikingly, upon online electrolytic reduction, supercharged proteins (e.g., α-lactalbumin) showed even higher charging, which will be useful in top- down protein structure MS analysis as increased charges are known to promote protein ion dissociation. Also, the separation speed and sensitivity are enhanced by approximately 1(~)2 orders of magnitude by using UPLC for the liquid chromatography (LC)/EC/MS platform, in comparison to the previously used high- performance liquid chromatography (HPLC). This UPLC/EC/DESI-MS method combines the power of fast UPLC separation, fast electrochemical conversion, and online MS structural analysis for a potentially valuable tool for proteomics research and bioanalysis.
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Affiliation(s)
- Yi Cai
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701 USA.
| | - Qiuling Zheng
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701 USA.
| | - Yong Liu
- Department of Analytical Chemistry, Merck Research Laboratories, Merck & Co., Inc., Rahway, NJ 07065, USA.
| | - Roy Helmy
- Department of Analytical Chemistry, Merck Research Laboratories, Merck & Co., Inc., Rahway, NJ 07065, USA.
| | - Joseph A Loo
- Dep artment of Chemistry and Biochemistry, Department of Biological Chemistry, David Geffen School of Medicine at UCLA, and UCLA/DOE Institute for Genomics and Proteomics, University of California-Los Angeles, Los Angeles, CA 90095, USA.
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701 USA.
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15
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Tan L, Tureček F, Francisco JS, Xia Y. Probing the radical and base dual properties of peptide sulfinyl radicals via mass spectrometry. J Phys Chem A 2014; 118:11828-35. [PMID: 25428214 DOI: 10.1021/jp510362p] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Heteroatom-centered radicals are known to play critical roles in atmospheric chemistry, organic synthesis, and biology. While most studies have focused on the radical reactivity such as hydrogen abstraction, the base properties of heteroatom-centered radicals have long been overlooked, despite the profound consequences, such as their ability to participate in hydrogen-bonding networks. In this study, we use the sulfinyl radical (-SO(•)) as a model to show that the dual properties of heteroatom-centered radicals, that is, their ability to function as a radical and a base, can coexist in peptides and be differentiated by examining the loss of hydrosulfinyl radical (SOH) upon unimolecular dissociation of the peptide sulfinyl radical ions in the gas phase. The loss of SOH can result from two channels; one involves hydrogen atom abstraction, which reflects the radical property; the other is initiated by proton transfer to the sulfinyl radical, manifesting its base property. Tuning of the two properties of peptide sulfinyl radicals can be achieved by varying the chemical properties of the neighboring functional groups, which demonstrates the influence of the local chemical environment on the behavior of the radical species. The experimental approach established in this study to probe the dual chemical property of the peptide sulfinyl radical can be potentially applied to studying other types of heteroatom-centered radical species of biological significance.
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Affiliation(s)
- Lei Tan
- Department of Chemistry, Purdue University , West Lafayette, Indiana 47907-2084, United States
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Stinson CA, Xia Y. Reactions of hydroxyalkyl radicals with cysteinyl peptides in a nanoESI plume. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1192-1201. [PMID: 24793576 DOI: 10.1007/s13361-014-0898-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 03/20/2014] [Accepted: 03/20/2014] [Indexed: 06/03/2023]
Abstract
In biological systems, carbon-centered small molecule radicals are primarily formed via external radiation or internal radical reactions. These radical species can react with a variety of biomolecules, most notably nucleic acids, the consequence of which has possible links to gene mutation and cancer. Sulfur-containing peptides and proteins are reactive toward a variety of radical species and many of them behave as radical scavengers. In this study, the reactions between alkyl alcohol carbon-centered radicals (e.g., •CH2OH for methanol) and cysteinyl peptides within a nanoelectrospray ionization (nanoESI) plume were explored. The reaction system involved ultraviolet (UV) irradiation of a nanoESI plume using a low pressure mercury lamp consisting of 185 and 254 nm emission bands. The alkyl alcohol was added as solvent into the nanoESI solution and served as the precursor of hydroxyalkyl radicals upon UV irradiation. The hydroxyalkyl radicals subsequently reacted with cysteinyl peptides either containing a disulfide linkage or free thiol, which led to the formation of peptide-S-hydroxyalkyl product. This radical reaction coupled with subsequent MS/MS was shown to have analytical potential by cleaving intrachain disulfide linked peptides prior to CID to enhance sequence information. Tandem mass spectrometry via collision-induced dissociation (CID), stable isotope labeling, and accurate mass measurement were employed to verify the identities of the reaction products.
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Affiliation(s)
- Craig A Stinson
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907-2084, USA
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Tan L, Hu H, Francisco JS, Xia Y. A mass spectrometric approach for probing the stability of bioorganic radicals. Angew Chem Int Ed Engl 2014; 53:1887-90. [PMID: 24446129 DOI: 10.1002/anie.201310480] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Indexed: 11/10/2022]
Abstract
Glycyl radicals are important bioorganic radical species involved in enzymatic catalysis. Herein, we demonstrate that the stability of glycyl-type radicals (X-(.) CH-Y) can be tuned on a molecular level by varying the X and Y substituents and experimentally probed by mass spectrometry. This approach is based on the gas-phase dissociation of cysteine sulfinyl radical (X-Cys SO .-Y) ions through homolysis of a Cα Cβ bond. This fragmentation produces a glycyl-type radical upon losing CH2 SO, and the degree of this loss is closely tied to the stability of the as-formed radical. Theoretical calculations indicate that the energy of the Cα Cβ bond homolysis is predominantly affected by the stability of the glycyl radical product through the captodative effect, rather than that of the parent sulfinyl radical. This finding suggests a novel experimental method to probe the stability of bioorganic radicals, which can potentially broaden our understanding of these important reactive intermediates.
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Affiliation(s)
- Lei Tan
- Department of Chemistry, Purdue University, West Lafayette, IN 47907 (USA)
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Tan L, Hu H, Francisco JS, Xia Y. A Mass Spectrometric Approach for Probing the Stability of Bioorganic Radicals. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201310480] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Durand KL, Ma X, Xia Y. Intra-molecular reactions as a new approach to investigate bio-radical reactivity: a case study of cysteine sulfinyl radicals. Analyst 2014; 139:1327-30. [PMID: 24511586 DOI: 10.1039/c3an02307a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Utilizing gas-phase intra-molecular reactions facilitated by energetic collisions, a new reaction channel, sulfinyl radical exchange with thiol within a polypeptide, was observed for the first time.
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Affiliation(s)
- Kirt L. Durand
- Department of Chemistry
- Purdue University
- West Lafayette, USA
| | - Xiaoxiao Ma
- Department of Chemistry
- Purdue University
- West Lafayette, USA
| | - Yu Xia
- Department of Chemistry
- Purdue University
- West Lafayette, USA
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Zheng Q, Zhang H, Chen H. Integration of online digestion and electrolytic reduction with mass spectrometry for rapid disulfide-containing protein structural analysis. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2013; 353:84-92. [PMID: 25419170 PMCID: PMC4240030 DOI: 10.1016/j.ijms.2013.04.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Bottom-up structural analysis of disulfide-bond containing proteins usually involves time-consuming offline enzymatic digestion, chemical reduction and thiol protection prior to mass spectrometric detection, which takes many hours. This paper presents an expedited bottom-up approach, employing desorption electrospray ionization-mass spectrometry (DESI-MS) coupled with online pepsin digestion and online electrochemical reduction of disulfide bonds. Peptides are generated in high digestion yield as its precursor protein in acidic aqueous solution flows through a pepsin column, which can undergo direct electrolysis. The electrolytic behaviors of peptides, as online monitored by DESI-MS, suggest the presence or absence of disulfide bonds in the peptides, and also provide information to relate disulfide bond-containing peptide precursors to their corresponding reduced products. Furthermore, selective electrolysis simply using different reduction potentials can be adopted to generate either partially or fully reduced peptides to assist disulfide bond mapping. In addition, it turns out that DESI is suitable for ionizing peptides in water without organic solvent additives (organic solvent additives would not be compatible with the use of pepsin column). The feasibility of this method was demonstrated using insulin, a protein carrying three pairs of disulfide-bonds as an example, in which all disulfide bond linkages and most of the protein sequence were successfully determined. Strikingly, this method shortens the sample digestion, reduction and MS detection from hours to less than 7 min, which could be of high value in high-throughput proteomics research.
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Affiliation(s)
- Qiuling Zheng
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA
| | - Hao Zhang
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
- Corresponding author. Tel.: +1 314 935 7486
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA
- Corresponding author. Tel.: +1 740 593 0719; fax: +1 740 597 3157
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