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Wang J, Curtin K, Valentine SJ, Li P. Unlocking the potential of 3D printed microfluidics for mass spectrometry analysis using liquid infused surfaces. Anal Chim Acta 2023; 1279:341792. [PMID: 37827686 PMCID: PMC10570538 DOI: 10.1016/j.aca.2023.341792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/22/2023] [Accepted: 09/06/2023] [Indexed: 10/14/2023]
Abstract
Combining microfluidics with mass spectrometry (MS) analysis has great potential for enabling new analytical applications and simplifying existing MS workflows. The rapid development of 3D printing technology has enabled direct fabrication of microfluidic channels using consumer grade 3D printers, which holds great promise to facilitate the adoption of microfluidic devices by the MS community. However, photo polymerization-based 3D printed devices have an issue with chemical leeching, which can introduce contaminant molecules that may present as isobaric ions and/or severely suppress the ionization of target analytes when combined with MS analysis. Although extra cure and washing steps have alleviated the leeching issue, many such contaminant peaks can still show up in mass spectra. In this work, we report a simple surface modification strategy to isolate the chemical leachates from the channel solution thereby eliminating the contaminant peaks for MS analysis. The channel was prepared by fabricating a layer of polydimethylsiloxane graft followed by wetting the graft using silicone oil. The resulting liquid infused surface (LIS) showed significant reduction in contaminant peaks and improvement in the signal intensity of target analytes. The coating showed good stability after long-term usage (7 days) and long-term storage (∼6 months). Finally, the utility of the coating strategy was demonstrated by printing herringbone microfluidic mixers for studying fast reaction kinetics, which obtained comparable reaction rates to literature values. The effectiveness, simplicity, and stability of the present method will promote the adoption of 3D printed microdevices by the MS community.
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Affiliation(s)
- Jing Wang
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
| | - Kathrine Curtin
- Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV, USA
| | - Stephen J Valentine
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA
| | - Peng Li
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV, USA.
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2
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Omics Approaches in Drug Development against Leishmaniasis: Current Scenario and Future Prospects. Pathogens 2022; 12:pathogens12010039. [PMID: 36678387 PMCID: PMC9866966 DOI: 10.3390/pathogens12010039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/28/2022] Open
Abstract
Leishmaniasis is a zoonotic disease transmitted in humans by the bite of Leishmania-infected phlebotomine sandflies. Each year approximately 58,500 cases of leishmaniasis are diagnosed across the globe, with a mortality rate of nearly seven percent. There are over 20 parasitic strains of Leishmania which are known to cause distinct types of leishmaniasis and pose an endemic threat to humans worldwide. Therefore, it is crucial to develop potential medications and vaccines to combat leishmaniasis. However, the task of developing therapeutic solutions is challenging due to Leishmania's digenetic lifecycle. The challenge is further intensified by cases of resistance against the available drugs. Owing to these challenges, the conventional drug development regimen is further limited by target discovery and ligand suitability for the targets. On the other hand, as an added advantage, the emergence of omics-based tools, such as high-end proteomics, transcriptomics and genomics, has hastened the pace of target discovery and target-based drug development. It is now becoming apparent that multi-omics convergence and an inter-connected systems approach is less time-consuming and more cost-effective for any drug-development process. This comprehensive review is an attempt to summarize the current knowledge on the muti-omics approach in drug development against leishmaniasis. In particular, it elaborates the potential target identification from secreted proteins in various stages of Leishmania infection and also illustrates the convergence of transcriptomic and genomic data towards the collective goal of drug discovery. This review also provides an understanding of the potential parasite's drug targets and drug resistance characteristics of the parasite, which can be used in designing effective and specific therapeutics.
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3
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Sun J, Yin Y, Li W, Jin O, Na N. CHEMICAL REACTION MONITORING BY AMBIENT MASS SPECTROMETRY. MASS SPECTROMETRY REVIEWS 2022; 41:70-99. [PMID: 33259644 DOI: 10.1002/mas.21668] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/16/2020] [Accepted: 10/22/2020] [Indexed: 06/12/2023]
Abstract
Chemical reactions conducted in different media (liquid phase, gas phase, or surface) drive developments of versatile techniques for the detection of intermediates and prediction of reasonable reaction pathways. Without sample pretreatment, ambient mass spectrometry (AMS) has been applied to obtain structural information of reactive molecules that differ in polarity and molecular weight. Commercial ion sources (e.g., electrospray ionization, atmospheric pressure chemical ionization, and direct analysis in real-time) have been reported to monitor substrates and products by offline reaction examination. While the interception or characterization of reactive intermediates with short lifetime are still limited by the offline modes. Notably, online ionization technologies, with high tolerance to salt, buffer, and pH, can achieve direct sampling and ionization of on-going reactions conducted in different media (e.g., liquid phase, gas phase, or surface). Therefore, short-lived intermediates could be captured at unprecedented timescales, and the reaction dynamics could be studied for mechanism examinations without sample pretreatments. In this review, via various AMS methods, chemical reaction monitoring and mechanism elucidation for different classifications of reactions have been reviewed. The developments and advances of common ionization methods for offline reaction monitoring will also be highlighted.
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Affiliation(s)
- Jianghui Sun
- Key Laboratory of Radiopharmaceuticals Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, People's Republic of China
| | - Yiyan Yin
- Key Laboratory of Radiopharmaceuticals Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, People's Republic of China
| | - Weixiang Li
- Key Laboratory of Radiopharmaceuticals Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, People's Republic of China
| | - Ouyang Jin
- Key Laboratory of Radiopharmaceuticals Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, People's Republic of China
| | - Na Na
- Key Laboratory of Radiopharmaceuticals Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, People's Republic of China
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4
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Lento C, Wilson DJ. Subsecond Time-Resolved Mass Spectrometry in Dynamic Structural Biology. Chem Rev 2021; 122:7624-7646. [PMID: 34324314 DOI: 10.1021/acs.chemrev.1c00222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Life at the molecular level is a dynamic world, where the key players-proteins, oligonucleotides, lipids, and carbohydrates-are in a perpetual state of structural flux, shifting rapidly between local minima on their conformational free energy landscapes. The techniques of classical structural biology, X-ray crystallography, structural NMR, and cryo-electron microscopy (cryo-EM), while capable of extraordinary structural resolution, are innately ill-suited to characterize biomolecules in their dynamically active states. Subsecond time-resolved mass spectrometry (MS) provides a unique window into the dynamic world of biological macromolecules, offering the capacity to directly monitor biochemical processes and conformational shifts with a structural dimension provided by the electrospray charge-state distribution, ion mobility, covalent labeling, or hydrogen-deuterium exchange. Over the past two decades, this suite of techniques has provided important insights into the inherently dynamic processes that drive function and pathogenesis in biological macromolecules, including (mis)folding, complexation, aggregation, ligand binding, and enzyme catalysis, among others. This Review provides a comprehensive account of subsecond time-resolved MS and the advances it has enabled in dynamic structural biology, with an emphasis on insights into the dynamic drivers of protein function.
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Affiliation(s)
- Cristina Lento
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Derek J Wilson
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
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5
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Yan X, Bain RM, Cooks RG. Organic Reactions in Microdroplets: Reaction Acceleration Revealed by Mass Spectrometry. Angew Chem Int Ed Engl 2018; 55:12960-12972. [PMID: 27530279 DOI: 10.1002/anie.201602270] [Citation(s) in RCA: 258] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 11/10/2022]
Abstract
The striking finding that reaction acceleration occurs in confined-volume solutions sets up an apparent conundrum: Microdroplets formed by spray ionization can be used to monitor the course of bulk-phase reactions and also to accelerate reactions between the reagents in such a reaction. This Minireview introduces droplet and thin-film acceleration phenomena and summarizes recent methods applied to study accelerated reactions in confined-volume, high-surface-area solutions. Conditions that dictate either simple monitoring or acceleration are reconciled in the occurrence of discontinuous and complete desolvation as the endpoint of droplet evolution. The contrasting features of microdroplet and bulk-solution reactions are described together with possible mechanisms that drive reaction acceleration in microdroplets. Current applications of droplet microreactors are noted as is reaction acceleration in confined volumes and possible future scale-up.
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Affiliation(s)
- Xin Yan
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907, USA
| | - Ryan M Bain
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907, USA
| | - R Graham Cooks
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907, USA.
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6
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Zheng Q, Tian Y, Ruan X, Chen H, Wu X, Xu X, Wang G, Hao H, Ye H. Probing specific ligand-protein interactions by native-denatured exchange mass spectrometry. Anal Chim Acta 2018; 1036:58-65. [PMID: 30253837 DOI: 10.1016/j.aca.2018.07.072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 07/21/2018] [Accepted: 07/27/2018] [Indexed: 10/28/2022]
Abstract
Probing ligand-target protein interactions provides essential information for deep understanding of biochemical machinery and design of drug screening assays. Native electrospray ionization-mass spectrometry (ESI-MS) is promising for direct analysis of ligand-protein complexes. However, it lacks the ability to distinguish between specific and non-specific ligand-protein interactions, and to further recognize the specifically bound proteins as drug target candidates, which remains as a major challenge in the field of drug developments by far. Herein we report a native-denatured exchange (NDX) mass spectrometry (MS) acquisition approach using a liquid sample-desorption electrospray ionization (LS-DESI) setup, and demonstrate its capability in enabling a change from native detection of noncovalent ligand-protein complexes to denatured analysis using three model ligand-protein complexes including myoglobin, CDP-ribonuclease and N,N',N″-triacetylchitotriose (NAG3)-lysozyme. Notably, we found the NDX-MS approach can readily discriminate specific ligand-protein interactions from nonspecific ones, as revealed by their distinct dynamic profiles of Kd as a function of the DESI spraying flow rate. Consequently, this NDX-MS approach holds promise for future applications to discovering specific protein targets for ligands of interest, and to screening compounds with high specificity to drug targets and thus eliminates off-target effects.
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Affiliation(s)
- Qiuling Zheng
- Department of Pharmaceutical Analysis, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China
| | - Yang Tian
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China
| | - Xujun Ruan
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, United States
| | - Xunxun Wu
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China
| | - Xiaowei Xu
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China
| | - Guangji Wang
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China
| | - Haiping Hao
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China.
| | - Hui Ye
- Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu, 210009, China.
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7
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Liu L, Deng L, Fan L, Huang X, Lu Y, Shen X, Jiang L, Silvain JF, Lu Y. Time-resolved resonance fluorescence spectroscopy for study of chemical reactions in laser-induced plasmas. OPTICS EXPRESS 2017; 25:27000-27007. [PMID: 29092181 DOI: 10.1364/oe.25.027000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/17/2017] [Indexed: 06/07/2023]
Abstract
Identification of chemical intermediates and study of chemical reaction pathways and mechanisms in laser-induced plasmas are important for laser-ablated applications. Laser-induced breakdown spectroscopy (LIBS), as a promising spectroscopic technique, is efficient for elemental analyses but can only provide limited information about chemical products in laser-induced plasmas. In this work, time-resolved resonance fluorescence spectroscopy was studied as a promising tool for the study of chemical reactions in laser-induced plasmas. Resonance fluorescence excitation of diatomic aluminum monoxide (AlO) and triatomic dialuminum monoxide (Al2O) was used to identify these chemical intermediates. Time-resolved fluorescence spectra of AlO and Al2O were used to observe the temporal evolution in laser-induced Al plasmas and to study their formation in the Al-O2 chemistry in air.
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8
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Cheng S, Wu Q, Dewald HD, Chen H. Online Monitoring of Methanol Electro-Oxidation Reactions by Ambient Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1005-1012. [PMID: 27562502 DOI: 10.1007/s13361-016-1450-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 05/25/2016] [Accepted: 07/10/2016] [Indexed: 06/06/2023]
Abstract
Online detection of methanol electro-oxidation reaction products [e.g., formaldehyde (HCHO)] by mass spectrometry (MS) is challenging, owing to the high salt content and extreme pH of the electrolyte solution as well as the difficulty in ionizing the reaction products. Herein we present an online ambient mass spectrometric approach for analyzing HCHO generated from methanol electro-oxidation, taking the advantage of high salt tolerance of desorption electrospray ionization mass spectrometry (DESI-MS). It was found that HCHO can be detected as PhNHNH+=CH2 (m/z 121) by DESI after online derivatization with PhNHNH2. With this approach, the analysis of HCHO from methanol electro-oxidation by MS was carried out not only in acidic condition but also in alkaline media for the first time. Efficiencies of different electrodes for methanol oxidation at different pHs were also evaluated. Our results show that Au electrode produces more HCHO than Pt-based electrodes at alkaline pH, while the latter have higher yields at acidic solution. The presented methodology would be of great value for elucidating fuel cell reaction mechanisms and for screening ideal fuel cell electrode materials. Graphical Abstract ᅟ.
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Affiliation(s)
- Si Cheng
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, USA
| | - Qiuhua Wu
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, USA
- College of Sciences, Agricultural University of Hebei, Baoding, Hebei, 071001, China
| | - Howard D Dewald
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, 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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9
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Cheng S, Wu Q, Xiao H, Chen H. Online Monitoring of Enzymatic Reactions Using Time-Resolved Desorption Electrospray Ionization Mass Spectrometry. Anal Chem 2017; 89:2338-2344. [DOI: 10.1021/acs.analchem.6b03975] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Si Cheng
- Center
for Intelligent Chemical Instrumentation, Department of Chemistry
and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701, United States,
| | - Qiuhua Wu
- Center
for Intelligent Chemical Instrumentation, Department of Chemistry
and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701, United States,
- Department
of Chemistry, College of Science, Agricultural University of Hebei, Baoding 071001, China
| | - He Xiao
- Center
for Intelligent Chemical Instrumentation, Department of Chemistry
and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701, United States,
| | - Hao Chen
- Center
for Intelligent Chemical Instrumentation, Department of Chemistry
and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701, United States,
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10
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Lento C, Wilson DJ. Unravelling the mysteries of sub-second biochemical processes using time-resolved mass spectrometry. Analyst 2017; 142:1640-1653. [DOI: 10.1039/c7an00338b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Many important chemical and biochemical phenomena proceed on sub-second time scales.
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Affiliation(s)
| | - Derek J. Wilson
- Department of Chemistry
- York University
- Toronto
- Canada
- Centre for Research of Biomolecular Interactions
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11
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Yan X, Bain RM, Cooks RG. Organische Reaktionen in Mikrotröpfchen: Analyse von Reaktionsbeschleunigungen durch Massenspektrometrie. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201602270] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Xin Yan
- Department of Chemistry Purdue University 560 Oval Drive West Lafayette IN 47907 USA
| | - Ryan M. Bain
- Department of Chemistry Purdue University 560 Oval Drive West Lafayette IN 47907 USA
| | - R. Graham Cooks
- Department of Chemistry Purdue University 560 Oval Drive West Lafayette IN 47907 USA
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12
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Meher AK, Chen YC. Online monitoring of chemical reactions by polarization-induced electrospray ionization. Anal Chim Acta 2016; 937:106-12. [DOI: 10.1016/j.aca.2016.07.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/07/2016] [Accepted: 07/12/2016] [Indexed: 01/09/2023]
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13
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Zheng Q, Chen H. Development and Applications of Liquid Sample Desorption Electrospray Ionization Mass Spectrometry. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2016; 9:411-448. [PMID: 27145689 DOI: 10.1146/annurev-anchem-071015-041620] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Desorption electrospray ionization mass spectrometry (DESI-MS) is a recent advance in the field of analytical chemistry. This review surveys the development of liquid sample DESI-MS (LS-DESI-MS), a variant form of DESI-MS that focuses on fast analysis of liquid samples, and its novel analy-tical applications in bioanalysis, proteomics, and reaction kinetics. Due to the capability of directly ionizing liquid samples, liquid sample DESI (LS-DESI) has been successfully used to couple MS with various analytical techniques, such as microfluidics, microextraction, electrochemistry, and chromatography. This review also covers these hyphenated techniques. In addition, several closely related ionization methods, including transmission mode DESI, thermally assisted DESI, and continuous flow-extractive DESI, are briefly discussed. The capabilities of LS-DESI extend and/or complement the utilities of traditional DESI and electrospray ionization and will find extensive and valuable analytical application in the future.
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Affiliation(s)
- Qiuling Zheng
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, and Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701;
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, and Edison Biotechnology Institute, Ohio University, Athens, Ohio 45701;
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14
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Mortensen DN, Williams ER. Ultrafast (1 μs) Mixing and Fast Protein Folding in Nanodrops Monitored by Mass Spectrometry. J Am Chem Soc 2016; 138:3453-60. [PMID: 26902747 DOI: 10.1021/jacs.5b13081] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The use of theta-glass emitters and mass spectrometry to monitor reactions that occur as fast as one μs is demonstrated. Acidified aqueous solutions containing unfolded proteins are mixed with aqueous ammonium acetate solutions to increase the solution pH and induce protein folding during nanoelectrospray ionization. Protein charge-state distributions show the extent to which folding occurs, and reaction times are obtained from known protein folding time constants. Shorter reaction times are obtained by decreasing the solution flow rate, and reaction times between 1.0 and 22 μs are obtained using flow rates between 48 and 2880 pL/s, respectively. Remarkably similar reaction times are obtained for three different proteins (Trp-cage, myoglobin, and cytochrome c) with folding time constants that differ by more than an order of magnitude (4.1, 7, and 57 μs, respectively), indicating that the reaction times obtained using rapid mixing from theta-glass emitters are independent of protein identity. A folding time constant of 2.2 μs is obtained for the formation of a β-hairpin structure of renin substrate tetradecapeptide, which is the fastest folding event measured using a rapid mixing technique. The 1.0 μs reaction time obtained here is about an order of magnitude lower than the shortest reaction time probed using a conventional mixer (8 μs). Moreover, this fast reaction time is obtained with a 48 pL/s flow rate, which is 2000-times less than the flow rate required to obtained the 8 μs reaction time using a conventional mixer. These results indicate that rapid mixing with theta-glass emitters can be used to access significantly faster reaction times while consuming substantially less sample than in conventional mixing apparatus.
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Affiliation(s)
- Daniel N Mortensen
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
| | - Evan R Williams
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
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15
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Cheng S, Wang J, Cai Y, Loo JA, Chen H. Enhancing Performance of Liquid Sample Desorption Electrospray Ionization Mass Spectrometry Using Trap and Capillary Columns. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2015; 392:73-79. [PMID: 27239159 PMCID: PMC4878830 DOI: 10.1016/j.ijms.2015.09.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Desorption electrospray ionization mass spectrometry (DESI-MS) is a recent and important advance in the field that has extensive applications in surface analysis of solid samples but has also been extended to analysis of liquid samples. The liquid sample DESI typically employs a piece of fused silica capillary to transfer liquid sample for ionization. In this study, we present the improvement of liquid sample DESI-MS by replacing the sample transfer silica capillary with a trap column filled with chromatographic stationary phase materials (e.g., C4, C18). This type of trap column/liquid sample DESI can be used for trace analysis of organics and biomolecules such as proteins/peptides (in nM concentration) in high salt content matrices. Furthermore, when the sample transfer capillary is modified with enzyme covalently bound on its inside capillary wall, fast digestion (< 6 min) of proteins such as phosphoproteins can be achieved and the online digested proteins can be directly ionized using DESI with high sensitivity. The latter is ascribed to the freedom to select favorable spray solvent for the DESI analysis. Our data shows that liquid sample DESI-MS with a modified sample transfer capillary has significantly expanded its utility in bioanalysis.
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Affiliation(s)
- Si Cheng
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, USA
| | - Jun Wang
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, USA ; Department of forensic science, Jiangsu Police Institute, Nanjing, Jiang Su, 210031, China
| | - Yi Cai
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, USA
| | - Joseph A Loo
- Department 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, California 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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16
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Liu YM, Perry RH. Paper-Based Electrochemical Cell Coupled to Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1702-1712. [PMID: 26311335 DOI: 10.1007/s13361-015-1224-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 06/15/2015] [Accepted: 06/17/2015] [Indexed: 06/04/2023]
Abstract
On-line coupling of electrochemistry (EC) to mass spectrometry (MS) is a powerful approach for identifying intermediates and products of EC reactions in situ. In addition, EC transformations have been used to increase ionization efficiency and derivatize analytes prior to MS, improving sensitivity and chemical specificity. Recently, there has been significant interest in developing paper-based electroanalytical devices as they offer convenience, low cost, versatility, and simplicity. This report describes the development of tubular and planar paper-based electrochemical cells (P-EC) coupled to sonic spray ionization (SSI) mass spectrometry (P-EC/SSI-MS). The EC cells are composed of paper sandwiched between two mesh stainless steel electrodes. Analytes and reagents can be added directly to the paper substrate along with electrolyte, or delivered via the SSI microdroplet spray. The EC cells are decoupled from the SSI source, allowing independent control of electrical and chemical parameters. We utilized P-EC/SSI-MS to characterize various EC reactions such as oxidations of cysteine, dopamine, polycyclic aromatic hydrocarbons, and diphenyl sulfide. Our results show that P-EC/SSI-MS has the ability to increase ionization efficiency, to perform online EC transformations, and to capture intermediates of EC reactions with a response time on the order of hundreds of milliseconds. The short response time allowed detection of a deprotonated diphenyl sulfide intermediate, which experimentally confirms a previously proposed mechanism for EC oxidation of diphenyl sulfide to pseudodimer sulfonium ion. This report introduces paper-based EC/MS via development of two device configurations (tubular and planar electrodes), as well as discusses the capabilities, performance, and limitations of the technique.
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Affiliation(s)
- Yao-Min Liu
- Department of Chemistry, University of Illinois, Urbana, IL, 61801, USA
| | - Richard H Perry
- Department of Chemistry, University of Illinois, Urbana, IL, 61801, USA.
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17
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Lu M, Liu Y, Helmy R, Martin GE, Dewald HD, Chen H. Online Investigation of Aqueous-Phase Electrochemical Reactions by Desorption Electrospray Ionization Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1676-1685. [PMID: 26242804 DOI: 10.1007/s13361-015-1210-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/16/2015] [Accepted: 05/29/2015] [Indexed: 06/04/2023]
Abstract
Electrochemistry (EC) combined with mass spectrometry (MS) is a powerful tool for elucidation of electrochemical reaction mechanisms. However, direct online analysis of electrochemical reaction in aqueous phase was rarely explored. This paper presents the online investigation of several electrochemical reactions with biological relevance in the aqueous phase, such as nitrosothiol reduction, carbohydrate oxidation, and carbamazepine oxidation using desorption electrospray ionization mass spectrometry (DESI-MS). It was found that electroreduction of nitrosothiols [e.g., nitrosylated insulin B (13-23)] leads to free thiols by loss of NO, as confirmed by online MS analysis for the first time. The characteristic mass shift of 29 Da and the reduced intensity provide a quick way to identify nitrosylated species. Equally importantly, upon collision-induced dissociation (CID), the reduced peptide ion produces more fragment ions than its nitrosylated precursor ion (presumably the backbone fragmentation cannot compete with the facile NO loss for the precursor ion), thus facilitating peptide sequencing. In the case of saccharide oxidation, it was found that glucose undergoes electro-oxidation to produce gluconic acid at alkaline pH, but not at neutral and acidic pHs. Such a pH-dependent electrochemical behavior was also observed for disaccharides such as maltose and cellobiose. Upon electrochemical oxidation, carbamazepine was found to undergo ring contraction and amide bond cleavage, which parallels the oxidative metabolism observed for this drug in leucocytes. The mechanistic information of these redox reactions revealed by EC/DESI-MS would be of value in nitroso-proteome research and carbohydrate/drug metabolic studies.
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Affiliation(s)
- Mei Lu
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, USA
| | - Yong Liu
- Department of Process and Analytical Chemistry, Merck Research Laboratories, Merck and Co., Inc., Rahway, NJ, 07065, USA.
| | - Roy Helmy
- Department of Process and Analytical Chemistry, Merck Research Laboratories, Merck and Co., Inc., Rahway, NJ, 07065, USA
| | - Gary E Martin
- Department of Process and Analytical Chemistry, Merck Research Laboratories, Merck and Co., Inc., Rahway, NJ, 07065, USA
| | - Howard D Dewald
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Edison Biotechnology Institute, Ohio University, Athens, OH, 45701, 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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18
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Ingram AJ, Boeser CL, Zare RN. Going beyond electrospray: mass spectrometric studies of chemical reactions in and on liquids. Chem Sci 2015; 7:39-55. [PMID: 28757996 PMCID: PMC5508663 DOI: 10.1039/c5sc02740c] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/01/2015] [Indexed: 12/16/2022] Open
Abstract
Recently developed and applied ionization techniques have brought mass spectrometry to bear on previously inaccessible chemistry. We offer our perspective on this field and its application for studying reaction mechanisms.
There has been a burst in the number and variety of available ionization techniques to use mass spectrometry to monitor chemical reactions in and on liquids. Chemists have gained the capability to access chemistry at unprecedented timescales, and monitor reactions and detect intermediates under almost any set of conditions. Herein, recently developed ionization techniques that facilitate mechanistic studies of chemical processes are reviewed. This is followed by a discussion of our perspective on the judicious application of these and similar techniques in order to study reaction mechanisms.
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Affiliation(s)
- Andrew J Ingram
- Department of Chemistry , Stanford University , Stanford , CA 94305 , USA .
| | | | - Richard N Zare
- Department of Chemistry , Stanford University , Stanford , CA 94305 , USA .
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19
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Peters KC, Comi TJ, Perry RH. Multistage Reactive Transmission-Mode Desorption Electrospray Ionization Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1494-1501. [PMID: 26091888 DOI: 10.1007/s13361-015-1171-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 04/16/2015] [Accepted: 04/18/2015] [Indexed: 06/04/2023]
Abstract
Elucidating reaction mechanisms is important for advancing many areas of science such as catalyst development. It is often difficult to probe fast reactions at ambient conditions with high temporal resolution. In addition, systems involving reagents that cross-react require analytical methods that can minimize interaction time and specify their order of introduction into the reacting system. Here, we explore the utility of transmission mode desorption electrospray ionization (TM-DESI) for reaction monitoring by directing a microdroplet spray towards a series of meshes with micrometer-sized openings coated with reagents, an approach we call multistage reactive TM-DESI (TM (n) -DESI, where n refers to the number of meshes; n = 2 in this report). Various stages of the reaction are initiated at each mesh surface, generating intermediates and products in microdroplet reaction vessels traveling towards the mass spectrometer. Using this method, we investigated the reactivity of iron porphyrin catalytic hydroxylation of propranolol and other substrates. Our experimental results indicate that TM (n) -DESI provides the ability to spatially separate reagents and control their order of introduction into the reacting system, thereby minimizing unwanted reactions that lead to catalyst deactivation and degradation products. In addition, comparison with DESI-MS analyses (the Zare and Latour laboratories published results suggesting accessible reaction times <1 ms) of the reduction of dichlorophenolindophenol by L-ascorbic acid suggest that TM (1) -DESI can access reaction times less than 1 ms. Multiple meshes allow sequential stages of desorption/ionization per MS scan, increasing the number of analytes and reactions that can be characterized in a single experiment.
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Affiliation(s)
- Kevin C Peters
- Department of Chemistry, University of Illinois, Urbana, IL, 61801, USA
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20
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Abstract
We investigated the fusion of high-speed liquid droplets as a way to record the kinetics of liquid-phase chemical reactions on the order of microseconds. Two streams of micrometer-size droplets collide with one another. The droplets that fused (13 μm in diameter) at the intersection of the two streams entered the heated capillary inlet of a mass spectrometer. The mass spectrum was recorded as a function of the distance x between the mass spectrometer inlet and the droplet fusion center. Fused droplet trajectories were imaged with a high-speed camera, revealing that the droplet fusion occurred approximately within a 500-μm radius from the droplet fusion center and both the size and the speed of the fused droplets remained relatively constant as they traveled from the droplet fusion center to the mass spectrometer inlet. Evidence is presented that the reaction effectively stops upon entering the heated inlet of the mass spectrometer. Thus, the reaction time was proportional to x and could be measured and manipulated by controlling the distance x. Kinetic studies were carried out in fused water droplets for acid-induced unfolding of cytochrome c and hydrogen-deuterium exchange in bradykinin. The kinetics of the former revealed the slowing of the unfolding rates at the early stage of the reaction within 50 μs. The hydrogen-deuterium exchange revealed the existence of two distinct populations with fast and slow exchange rates. These studies demonstrated the power of this technique to detect reaction intermediates in fused liquid droplets with microsecond temporal resolution.
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21
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Baez NOD, Reisz JA, Furdui CM. Mass spectrometry in studies of protein thiol chemistry and signaling: opportunities and caveats. Free Radic Biol Med 2015; 80:191-211. [PMID: 25261734 PMCID: PMC4355329 DOI: 10.1016/j.freeradbiomed.2014.09.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 09/08/2014] [Accepted: 09/11/2014] [Indexed: 12/13/2022]
Abstract
Mass spectrometry (MS) has become a powerful and widely utilized tool in the investigation of protein thiol chemistry, biochemistry, and biology. Very early biochemical studies of metabolic enzymes have brought to light the broad spectrum of reactivity profiles that distinguish cysteine thiols with functions in catalysis and protein stability from other cysteine residues in proteins. The development of MS methods for the analysis of proteins using electrospray ionization (ESI) or matrix-assisted laser desorption/ionization (MALDI) coupled with the emergence of high-resolution mass analyzers has been instrumental in advancing studies of thiol modifications, both in single proteins and within the cellular context. This article reviews MS instrumentation and methods of analysis employed in investigations of thiols and their reactivity toward a range of small biomolecules. A selected number of studies are detailed to highlight the advantages brought about by the MS technologies along with the caveats associated with these analyses.
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Affiliation(s)
- Nelmi O Devarie Baez
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Julie A Reisz
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Cristina M Furdui
- Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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22
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Lento C, Audette GF, Wilson DJ. Time-resolved electrospray mass spectrometry — a brief history. CAN J CHEM 2015. [DOI: 10.1139/cjc-2014-0260] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
This review describes the evolution of time-resolved electrospray ionization mass spectrometry (TRESI-MS), a technology that was developed in large part at Western University. TRESI-MS was initially designed to characterize rapid chemical and biochemical reactions occurring on the millisecond time scale without need for a chromophore. Early TRESI-MS setups usually consisted of continuous-flow rapid mixers with a fixed tee for analysis of a single time point, and later adjustable reaction chamber devices allowing for automatic tracking of the reaction over time. Advances in instrumentation design over the years have resulted in improved time resolution, with microfluidic device implementation allowing for coupling to hydrogen−deuterium exchange (HDX) experiments. Areas of application that will be discussed include the investigation of protein folding intermediates, identification of enzyme−substrate intermediates in the pre-steady state, and the use of time-resolved HDX to study the dynamics of weakly structured protein regions. While some limitations still persist with the method, the continued development of TRESI-MS and related approaches paves the way to a promising future and the study of unexplored application areas.
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Affiliation(s)
- Cristina Lento
- Department of Chemistry, York University, Toronto, ON M3J 1P3, Canada
| | - Gerald F. Audette
- Department of Chemistry, York University, Toronto, ON M3J 1P3, Canada
- Center for Research on Biomolecular Interactions, Department of Chemistry, York University, Toronto, ON M3J 1P3, Canada
| | - Derek J. Wilson
- Department of Chemistry, York University, Toronto, ON M3J 1P3, Canada
- Center for Research on Biomolecular Interactions, Department of Chemistry, York University, Toronto, ON M3J 1P3, Canada
- Center for Research in Mass Spectrometry, Department of Chemistry, York University, Toronto, ON, M3J 1P3, Canada
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23
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Hopper JTS, Robinson CV. Mass spectrometry quantifies protein interactions--from molecular chaperones to membrane porins. Angew Chem Int Ed Engl 2014; 53:14002-15. [PMID: 25354304 DOI: 10.1002/anie.201403741] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Indexed: 12/16/2022]
Abstract
Proteins possess an intimate relationship between their structure and function, with folded protein structures generating recognition motifs for the binding of ligands and other proteins. Mass spectrometry (MS) can provide information on a number of levels of protein structure, from the primary amino acid sequence to its three-dimensional fold and quaternary interactions. Given that MS is a gas-phase technique, with its foundations in analytical chemistry, it is perhaps counter-intuitive to use it to study the structure and non-covalent interactions of proteins that form in solution. Herein we show, however, that MS can go beyond simply preserving protein interactions in the gas phase by providing new insight into dynamic interaction networks, dissociation mechanisms, and the cooperativity of ligand binding. We consider potential pitfalls in data interpretation and place particular emphasis on recent studies that revealed quantitative information about dynamic protein interactions, in both soluble and membrane-embedded assemblies.
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Affiliation(s)
- Jonathan T S Hopper
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ (UK)
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24
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Hopper JTS, Robinson CV. Massenspektrometrie zur Quantifizierung von Wechselwirkungen zwischen Proteinen - von molekularen Chaperonen zu Membranporinen. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201403741] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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25
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Mortensen D, Williams ER. Theta-glass capillaries in electrospray ionization: rapid mixing and short droplet lifetimes. Anal Chem 2014; 86:9315-21. [PMID: 25160559 PMCID: PMC4165459 DOI: 10.1021/ac502545r] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/26/2014] [Indexed: 02/06/2023]
Abstract
Double-barrel wire-in-a-capillary electrospray emitters prepared from theta-glass capillaries were used to mix solutions during the electrospray process. The relative flow rate of each barrel was continuously monitored with internal standards. The complexation reaction of 18-crown-6 and K(+), introduced from opposite barrels, reaches equilibrium during the electrospray process, suggesting that complete mixing also occurs. A simplified diffusion model suggests that mixing occurs in less than a millisecond, and contributions of turbulence, estimated from times of coalescing ballistic microdroplets, suggest that complete mixing occurs within a few microseconds. This mixing time is 2 orders of magnitude less than in any mixer previously coupled to a mass spectrometer. The reduction of 2,6-dichloroindophenol by l-ascorbic acid was performed using the theta-glass emitters and monitored using mass spectrometry. On the basis of the rate constant of this reaction in bulk solution, an apparent reaction time of 274 ± 60 μs was obtained. This reaction time is an upper limit to the droplet lifetime because the surface area to volume ratio and the concentration of reagents increase as the droplet evaporates and some product formation occurs in the Taylor cone prior to droplet formation. On the basis of increases in reaction rates measured by others in droplets compared to rates in bulk solution, the true droplet lifetime is likely 1-3 orders of magnitude less than the upper limit, i.e., between 27 μs and 270 ns. The rapid mixing and short droplet lifetime achieved in these experiments should enable the monitoring of many different fast reactions using mass spectrometry.
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Affiliation(s)
- Daniel
N. Mortensen
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Evan R. Williams
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
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26
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Cai Y, Adams D, Chen H. A new splitting method for both analytical and preparative LC/MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:286-92. [PMID: 24254577 DOI: 10.1007/s13361-013-0763-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 09/18/2013] [Accepted: 09/28/2013] [Indexed: 05/28/2023]
Abstract
This paper presents a novel splitting method for liquid chromatography/mass spectrometry (LC/MS) application, which allows fast MS detection of LC-separated analytes and subsequent online analyte collection. In this approach, a PEEK capillary tube with a micro-orifice drilled on the tube side wall is used to connect with LC column. A small portion of LC eluent emerging from the orifice can be directly ionized by desorption electrospray ionization (DESI) with negligible time delay (6~10 ms) while the remaining analytes exiting the tube outlet can be collected. The DESI-MS analysis of eluted compounds shows narrow peaks and high sensitivity because of the extremely small dead volume of the orifice used for LC eluent splitting (as low as 4 nL) and the freedom to choose favorable DESI spray solvent. In addition, online derivatization using reactive DESI is possible for supercharging proteins and for enhancing their signals without introducing extra dead volume. Unlike UV detector used in traditional preparative LC experiments, this method is applicable to compounds without chromophores (e.g., saccharides) due to the use of MS detector. Furthermore, this splitting method well suits monolithic column-based ultra-fast LC separation at a high elution flow rate of 4 mL/min. Figure ᅟ
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Affiliation(s)
- Yi Cai
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH, 45701, USA
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27
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Liu P, Zhang J, Ferguson CN, Chen H, Loo JA. Measuring protein-ligand interactions using liquid sample desorption electrospray ionization mass spectrometry. Anal Chem 2013; 85:11966-72. [PMID: 24237005 PMCID: PMC3901310 DOI: 10.1021/ac402906d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We have previously shown that liquid sample desorption electrospray ionization-mass spectrometry (DESI-MS) is able to measure large proteins and noncovalently bound protein complexes (to 150 kDa) (Ferguson et al., Anal. Chem. 2011, 83, 6468-6473). In this study, we further investigate the application of liquid sample DESI-MS to probe protein-ligand interactions. Liquid sample DESI allows the direct formation of intact protein-ligand complex ions by spraying ligands toward separate protein sample solutions. This type of "reactive" DESI methodology can provide rapid information on binding stiochiometry, selectivity, and kinetics, as demonstrated by the binding of ribonuclease A (RNaseA, 13.7 kDa) with cytidine nucleotide ligands and the binding of lysozyme (14.3 kDa) with acetyl chitose ligands. A higher throughput method for ligand screening by liquid sample DESI was demonstrated, in which different ligands were sequentially injected as a segmented flow for DESI ionization. Furthermore, supercharging to enhance analyte charge can be integrated with liquid sample DESI-MS, without interfering with the formation of protein-ligand complexes.
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Affiliation(s)
- Pengyuan Liu
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, United States
| | - Jiang Zhang
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
| | - Carly N. Ferguson
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701, United States
| | - Joseph A. Loo
- Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, California 90095, United States
- Department of Biological Chemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095, United States
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28
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Pan N, Liu P, Cui W, Tang B, Shi J, Chen H. Highly efficient ionization of phosphopeptides at low pH by desorption electrospray ionization mass spectrometry. Analyst 2013; 138:1321-1324. [PMID: 23338759 DOI: 10.1039/c3an36737a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A fast and novel strategy for efficient ionization of phosphopeptides in mixtures is reported, in which the sample is acidified to low pH to suppress the deprotonation of phosphate groups and then followed by direct analysis using liquid sample desorption electrospray ionization mass spectrometry (DESI-MS).
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Affiliation(s)
- Ning Pan
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan, China, 250014.,Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USA 45701
| | - Pengyuan Liu
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USA 45701
| | - Weidong Cui
- Department of Chemistry, Washington University, St. Louis, MO, USA 63130
| | - Bo Tang
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan, China, 250014
| | - Jingmin Shi
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University, Jinan, China, 250014
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USA 45701
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29
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Chung K, Banik SM, De Crisci AG, Pearson DM, Blake TR, Olsson JV, Ingram AJ, Zare RN, Waymouth RM. Chemoselective Pd-catalyzed oxidation of polyols: synthetic scope and mechanistic studies. J Am Chem Soc 2013; 135:7593-602. [PMID: 23659308 DOI: 10.1021/ja4008694] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The regio- and chemoselective oxidation of unprotected vicinal polyols with [(neocuproine)Pd(OAc)]2(OTf)2 (1) (neocuproine = 2,9-dimethyl-1,10-phenanthroline) occurs readily under mild reaction conditions to generate α-hydroxy ketones. The oxidation of vicinal diols is both faster and more selective than the oxidation of primary and secondary alcohols; vicinal 1,2-diols are oxidized selectively to hydroxy ketones, whereas primary alcohols are oxidized in preference to secondary alcohols. Oxidative lactonization of 1,5-diols yields cyclic lactones. Catalyst loadings as low as 0.12 mol % in oxidation reactions on a 10 g scale can be used. The exquisite selectivity of this catalyst system is evident in the chemoselective and stereospecific oxidation of the polyol (S,S)-1,2,3,4-tetrahydroxybutane [(S,S)-threitol] to (S)-erythrulose. Mechanistic, kinetic, and theoretical studies revealed that the rate laws for the oxidation of primary and secondary alcohols differ from those of diols. Density functional theory calculations support the conclusion that β-hydride elimination to give hydroxy ketones is product-determining for the oxidation of vicinal diols, whereas for primary and secondary alcohols, pre-equilibria favoring primary alkoxides are product-determining. In situ desorption electrospray ionization mass spectrometry (DESI-MS) revealed several key intermediates in the proposed catalytic cycle.
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Affiliation(s)
- Kevin Chung
- Department of Chemistry, Stanford University, Stanford, California 94306, USA
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30
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Su HF, Xue L, Li YH, Lin SC, Wen YM, Huang RB, Xie SY, Zheng LS. Probing Hydrogen Bond Energies by Mass Spectrometry. J Am Chem Soc 2013; 135:6122-9. [DOI: 10.1021/ja312133k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Hai-Feng Su
- State Key Laboratory for Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Lan Xue
- Department of Chemistry, Ningde Normal University, Ningde 352100, China
| | - Yun-Hua Li
- State Key Laboratory for Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Shui-Chao Lin
- State Key Laboratory for Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yi-Mei Wen
- State Key Laboratory for Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Rong-Bin Huang
- State Key Laboratory for Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Su-Yuan Xie
- State Key Laboratory for Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Lan-Sun Zheng
- State Key Laboratory for Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
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31
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32
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Xu X, Na N, Wen J, Ouyang J. Detection of layer-by-layer self-assembly multilayer films by low-temperature plasma mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:172-178. [PMID: 23378089 DOI: 10.1002/jms.3141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 10/24/2012] [Accepted: 11/14/2012] [Indexed: 06/01/2023]
Abstract
The detection of layer-by-layer self-assembly multilayer films was carried out using low-temperature plasma (LTP) mass spectrometry (MS) under ambient conditions. These multilayer films have been prepared on quartz plates through the alternate assembling of oppositely charged 4-aminothiophenol (4-ATP) capped Au particles and thioglycolic acid (TGA) capped Ag particles. An LTP probe was used for direct desorption and ionization of chemical components on the films. Without the complicated sample preparation, the structure information of 4-ATP and TGA on films was studied by LTP-MS. Characteristic ions of 4-ATP (M) and TGA (F), including [M](+•), [M-NH(2)](+), [M-HCN-H](+), and [F + H](+), [F-H](+), [F-OH](+), [F-COOH](+) were recorded by LTP-MS on the films. However, [M-CS-H](+) and [F-SH](+) could not be observed on the film, which were detected in the neat sample. In addition, the semi-quantitative analysis of chemical components on monolayer film was carried out, and the amounts of 4-ATP and TGA on monolayer surface were 45 ng/mm(2) and 54 ng/mm(2), respectively. This resulted the ionization efficiencies of 72% for 4-ATP and 54% for TGA. In order to evaluate the reliability of present LTP-MS, the correlations between this approach and some traditional methods, such as UV-vis spectroscopy, atomic force microscope and X-ray photoelectron spectroscopy were studied, which resulted the correlation coefficients of higher than 0.9776. The results indicated that this technique can be used for analyzing the films without any pretreatment, which possesses great potential in the studies of self-assembly multilayer films.
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Affiliation(s)
- Xiangyu Xu
- College of Chemistry, Beijing Normal University, Beijing, 100875, PR China
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33
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Badu-Tawiah AK, Eberlin LS, Ouyang Z, Cooks RG. Chemical aspects of the extractive methods of ambient ionization mass spectrometry. Annu Rev Phys Chem 2013; 64:481-505. [PMID: 23331308 DOI: 10.1146/annurev-physchem-040412-110026] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ambient ionization techniques allow complex chemical samples to be analyzed in their native state with minimal sample preparation. This brings the obvious advantages of simplicity, speed, and versatility to mass spectrometry: Desorption electrospray ionization (DESI), for example, is used in chemical imaging for tumor margin diagnosis. This review on the extractive methods of ambient ionization focuses on chemical aspects, mechanistic considerations, and the accelerated chemical reactions occurring in charged liquid droplets generated in the spray process. DESI uses high-velocity solvent droplets to extract analytes from surfaces. Nano-DESI employs liquid microjunctions for analyte dissolution, whereas paper-spray ionization uses DC potentials applied to wet porous material such as paper or biological tissue to field emit charged analyte-containing solvent droplets. These methods also operate in a reactive mode in which added reagents allow derivatization during ionization. The accelerated reaction rates seen in charged microdroplets are useful in small-scale rapid chemical synthesis.
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34
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Monge ME, Harris GA, Dwivedi P, Fernández FM. Mass Spectrometry: Recent Advances in Direct Open Air Surface Sampling/Ionization. Chem Rev 2013; 113:2269-308. [DOI: 10.1021/cr300309q] [Citation(s) in RCA: 404] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- María Eugenia Monge
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332,
United States
| | - Glenn A. Harris
- Department
of Biochemistry and
the Mass Spectrometry Research Center, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Prabha Dwivedi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332,
United States
| | - Facundo M. Fernández
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332,
United States
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35
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Liu P, Lu M, Zheng Q, Zhang Y, Dewald HD, Chen H. Recent advances of electrochemical mass spectrometry. Analyst 2013; 138:5519-39. [DOI: 10.1039/c3an00709j] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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36
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Deng L, Kitova EN, Klassen JS. Dissociation kinetics of the streptavidin-biotin interaction measured using direct electrospray ionization mass spectrometry analysis. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:49-56. [PMID: 23247970 DOI: 10.1007/s13361-012-0533-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 10/31/2012] [Accepted: 11/02/2012] [Indexed: 06/01/2023]
Abstract
Dissociation rate constants (k (off)) for the model high affinity interaction between biotin (B) and the homotetramer of natural core streptavidin (S(4)) were measured at pH 7 and temperatures ranging from 15 to 45 °C using electrospray ionization mass spectrometry (ESI-MS). Two different approaches to data analysis were employed, one based on the initial rate of dissociation of the (S(4) + 4B) complex, the other involving nonlinear fitting of the time-dependent relative abundances of the (S(4) + iB) species. The two methods were found to yield k (off) values that are in good agreement, within a factor of two. The Arrhenius parameters for the dissociation of the biotin-streptavidin interaction in solution were established from the k (off) values determined by ESI-MS and compared with values measured using a radiolabeled biotin assay. Importantly, the dissociation activation energies determined by ESI-MS agree, within 1 kcal mol(-1), with the reported value. In addition to providing a quantitative measure of k (off), the results of the ESI-MS measurements revealed that the apparent cooperative distribution of (S(4) + iB) species observed at short reaction times is of kinetic origin and that sequential binding of B to S(4) occurs in a noncooperative fashion with the four ligand binding sites being kinetically and thermodynamically equivalent and independent.
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Affiliation(s)
- Lu Deng
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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Zhu W, Yuan Y, Zhou P, Zeng L, Wang H, Tang L, Guo B, Chen B. The expanding role of electrospray ionization mass spectrometry for probing reactive intermediates in solution. Molecules 2012; 17:11507-37. [PMID: 23018925 PMCID: PMC6268401 DOI: 10.3390/molecules171011507] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 08/29/2012] [Accepted: 09/05/2012] [Indexed: 12/31/2022] Open
Abstract
Within the past decade, electrospray ionization mass spectrometry (ESI-MS) has rapidly occupied a prominent position for liquid-phase mechanistic studies due to its intrinsic advantages allowing for efficient "fishing" (rapid, sensitive, specific and simultaneous detection/identification) of multiple intermediates and products directly from a "real-world" solution. In this review we attempt to offer a comprehensive overview of the ESI-MS-based methodologies and strategies developed up to date to study reactive species in reaction solutions. A full description of general issues involved with probing reacting species from complex (bio)chemical reaction systems is briefly covered, including the potential sources of reactive intermediate (metabolite) generation, analytical aspects and challenges, basic rudiments of ESI-MS and the state-of-the-art technology. The main purpose of the present review is to highlight the utility of ESI-MS and its expanding role in probing reactive intermediates from various reactions in solution, with special focus on current progress in ESI-MS-based approaches for improving throughput, testing reality and real-time detection by using newly developed MS instruments and emerging ionization sources (such as ambient ESI techniques). In addition, the limitations of modern ESI-MS in detecting intermediates in organic reactions is also discussed.
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Affiliation(s)
- Weitao Zhu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Yu Yuan
- School of Pharmaceutical Sciences, Central South University, 172 Tongzipo Road, Changsha 410013, China;
| | - Peng Zhou
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Le Zeng
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Hua Wang
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Ling Tang
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Bin Guo
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
| | - Bo Chen
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), Hunan Normal University, 36 Lushan Road, Changsha 410081, China; (W.Z.); (P.Z.); (L.Z.); (H.W.); (L.T.); (B.C.)
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38
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Schröder D. Applications of electrospray ionization mass spectrometry in mechanistic studies and catalysis research. Acc Chem Res 2012; 45:1521-32. [PMID: 22702223 DOI: 10.1021/ar3000426] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mechanistic studies form the basis for a better understanding of chemical processes, helping researchers develop more sustainable reactions by increasing the yields of the desired products, reducing waste production, and lowering the consumption of resources and energy overall. Conventional methods for the investigation of reaction mechanisms in solution include kinetic studies, isotope labeling, trapping of reactive intermediates, and advanced spectroscopic techniques. Within the past decade, electrospray ionization mass spectrometry (ESI-MS) has provided an additional tool for mechanistic studies because researchers can directly probe liquid samples by mass spectrometry under gentle conditions. Specifically, ESI-MS allows researchers to identify the molecular entities present in solution over the course of a chemical transformation. ESI-MS is particularly useful for investigations of organic reactions or metal catalysis that involve ionic intermediates. Accordingly, researchers are increasingly using ESI-MS in mechanistic studies and catalyst development. However, a further understanding of the ESI process and how it can facilitate mechanistic studies has not accompanied this increased use of the technique. Therefore, at least in part the ESI-MS method not only has offered great promise for the elucidation of reaction mechanisms but also became a black box with the occasional risk of misinterpretation. In this Account, we summarize applications of ESI-MS for synthetic and mechanistic research. Recently researchers have established direct linkages between gas-phase data obtained via ESI-MS and processes occurring in solution, and these results reveal qualitative and quantitative correlations between ESI-MS measurements and solution properties. In this context, time dependences, concentration series, and counterion effects can serve as criteria that allow researchers assess if the gas-phase measurements correlate with the situation in the solution. Furthermore, we report developments that bridge the gap between gas-phase and solution-phase studies. We also describe predictions derived from ESI-MS that have been verified with solution-phase chemistry experiments.
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Affiliation(s)
- Detlef Schröder
- Institute of Organic Chemistry and Biochemistry, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
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Liu Y, Miao Z, Lakshmanan R, Ogorzalek Loo RR, Loo JA, Chen H. Signal and Charge Enhancement for Protein Analysis by Liquid Chromatography-Mass Spectrometry with Desorption Electrospray Ionization. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2012; 325-327:161-166. [PMID: 25878557 PMCID: PMC4394628 DOI: 10.1016/j.ijms.2012.06.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We recently reported the use of desorption electrospray ionization (DESI) as a novel interface to couple high-performance liquid chromatography (HPLC) with mass spectrometry (MS) (Chem. Commun. 2011, 47, 4171). One of the benefits of such an interface is that post-column derivatization of separated analytes can be integrated with ionization via a "reactive" DESI approach in which a derivatizing reagent is doped into the spray solvent. The reactive DESI interface allows analyte desorption/ionization from the end of the chromatographic column with prompt MS detection; a short time delay of ~20 ms was demonstrated. In this study, we extended this application by "supercharging" proteins following HPLC separation using a DESI spray solvent containing supercharging reagents, m-nitrobenzyl alcohol (m-NBA) or sulfolane. Proteins (insulin, ubiquitin, lysozyme and α-lactalbumin) eluted out of the LC column can be supercharged with the protein charge state distributions (CSDs) significantly increased (to higher charge), which would be advantageous for subsequent top-down MS analysis of proteins. Interestingly, supercharging combined with reactive DESI enhances tolerance towards trifluoroacetic acid (TFA), which is known to be a superior additive in the mobile phase for premium peptide/protein chromatographic separation but has severe signal suppression effects for conventional electrospray ionization (ESI). In comparison to electrosonic spray ionization (ESSI), a variant form of ESI, the sensitivity of protein analysis using LC/DESI-MS with the mobile phase containing TFA can be improved by up to 70-fold for lysozyme and α-lactalbumin by including m-NBA in the DESI spray solvent. Presumably, by reducing TFA dissociation in the droplet, supercharging agents lower trifluoroacetate anion concentrations and concomitantly reduce ion pairing to analyte cationic sites. The reduced ion pairing therefore decreases the TFA signal suppression effect. The supercharging capability and the reduction of TFA signal suppression suggest that LC/DESI-MS is a valuable method for protein analysis.
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Affiliation(s)
- Yan Liu
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USA
| | - Zhixin Miao
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USA
| | - Rajeswari Lakshmanan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Rachel R Ogorzalek Loo
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA ; Department of Biological Chemistry, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH, USA
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Hsieh CH, Chao CS, Mong KKT, Chen YC. Online monitoring of chemical reactions by contactless atmospheric pressure ionization mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2012; 47:586-590. [PMID: 22576871 DOI: 10.1002/jms.2983] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Lu M, Wolff C, Cui W, Chen H. Investigation of some biologically relevant redox reactions using electrochemical mass spectrometry interfaced by desorption electrospray ionization. Anal Bioanal Chem 2012; 403:355-65. [PMID: 22237914 PMCID: PMC3731448 DOI: 10.1007/s00216-011-5679-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/12/2011] [Accepted: 12/18/2011] [Indexed: 10/14/2022]
Abstract
Recently we have shown that, as a versatile ionization technique, desorption electrospray ionization (DESI) can serve as a useful interface to combine electrochemistry (EC) with mass spectrometry (MS). In this study, the EC/DESI-MS method has been further applied to investigate some aqueous phase redox reactions of biological significance, including the reduction of peptide disulfide bonds and nitroaromatics as well as the oxidation of phenothiazines. It was found that knotted/enclosed disulfide bonds in the peptides apamin and endothelin could be electrochemically cleaved. Subsequent tandem MS analysis of the resulting reduced peptide ions using collision-induced dissociation (CID) and electron-capture dissociation (ECD) gave rise to extensive fragment ions, providing a fast protocol for sequencing peptides with complicated disulfide bond linkages. Flunitrazepam and clonazepam, a class of nitroaromatic drugs, are known to undergo reduction into amines which was proposed to involve nitroso and N-hydroxyl intermediates. Now in this study, these corresponding intermediate ions were successfully intercepted and their structures were confirmed by CID. This provides mass spectrometric evidence for the mechanism of the nitro to amine conversion process during nitroreduction, an important redox reaction involved in carcinogenesis. In addition, the well-known oxidation reaction of chlorpromazine was also examined. The putative transient one-electron transfer product, the chlorpromazine radical cation (m/z 318), was captured by MS, for the first time, and its structure was also verified by CID. In addition to these observations, some features of the DESI-interfaced electrochemical mass spectrometry were discussed, such as simple instrumentation and the lack of background signal. These results further demonstrate the feasibility of EC/DESI-MS for the study of the biology-relevant redox chemistry and would find applications in proteomics and drug development research.
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Affiliation(s)
- Mei Lu
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA
| | - Chloe Wolff
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA
| | - Weidong Cui
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - Hao Chen
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA
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Transient Ru-methyl formate intermediates generated with bifunctional transfer hydrogenation catalysts. Proc Natl Acad Sci U S A 2012; 109:2246-50. [PMID: 22315417 DOI: 10.1073/pnas.1118934109] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Desorption electrospray ionization (DESI) coupled to high-resolution Orbitrap mass spectrometry (MS) was used to study the reactivity of a (β-amino alcohol)(arene)RuCl transfer hydrogenation catalytic precursor in methanol (CH(3)OH). By placing [(p-cymene)RuCl(2)](2) on a surface and spraying a solution of β-amino alcohol in methanol, two unique transient intermediates having lifetimes in the submillisecond to millisecond range were detected. These intermediates were identified as Ru (II) and Ru (IV) complexes incorporating methyl formate (HCOOCH(3)). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that O(2) dissolved in the solvent is necessary for oxidizing Ru (II) to Ru (IV). These proposed intermediates are supported by high-resolution and high mass accuracy measurements and by comparing experimental to calculated isotope profiles. Additionally, analyzing the bulk reaction mixture using gas chromatography-MS and nuclear magnetic resonance spectroscopy confirms the formation of HCOOCH(3). These results represent an example that species generated from the (β-amino alcohol)(arene)RuCl (II) catalytic precursor can selectively oxidize CH(3)OH to HCOOCH(3). This observation leads us to propose a pathway that can compete with the hydrogen transfer catalytic cycle. Although bifunctional hydrogen transfer with Ru catalysts has been well-studied, the ability of DESI to intercept intermediates formed in the first few milliseconds of a chemical reaction allowed identification of previously unrecognized intermediates and reaction pathways in this catalytic system.
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43
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Rob T, Wilson DJ. Time-resolved mass spectrometry for monitoring millisecond time-scale solution-phase processes. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2012; 18:205-214. [PMID: 22641726 DOI: 10.1255/ejms.1176] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Many chemical and biochemical reactions equilibrate within a few seconds of initiation under "native" conditions. To understand the microscopic processes underlying these reactions, the most direct approach is to monitor the reaction as equilibrium is established (i.e. the reaction kinetics). However, this requires the ability to characterize the reaction mixture on the millisecond time-scale. In this review, we survey the contributions of time-resolved mass spectrometry (TR-MS) to the characterization of millisecond time-scale (bio)chemical processes, with a focus on biochemical applications. Compared to conventional time-resolved techniques, which use optical detection, the primary advantage of TR-MS is the ability to detect virtually all reactive species simultaneously. This provides a singularly high detail account of the reaction without the need for a chromophoric change on turnover or artificial chromophoric probes. To provide millisecond time-resolution, TR-MS set-ups usually employ continuous-flow rapid mixers, corresponding either to a fixed "tee" that provides a single reaction time-point or an adjustable position mixer that allows continuous reaction monitoring. TR-MS has been used to monitor processes with rates up to 500 s(-1) and to provide a detailed account of complex reactions involving 10 co- populated species. This corresponds to significantly lower time-resolution than optical methods, which can measure rates in excess of 900 s(-1) under ideal conditions, but substantially more detail (optical studies are typically limited to one or two analytes). TR-MS has been implemented on a number of platforms, including capillary and microfluidic set-ups. Capillary-based implementations are straightforward to fabricate and provide the most efficient rapid mixing. Microfluidic implementations have also been devised to enable multi-step experimental workflows that incorporate TR-MS. As a general method for time-resolved measurements, the applications for TR-MS are wide ranging. TR-MS has been used to identify intermediates in organic reactions, reveal protein (un)folding mechanisms, monitor enzyme catalysis in the pre-steady-state and, in conjunction with hydrogen-deuterium exchange, characterize protein conformational dynamics. While not without limitations, TR-MS represents a powerful alternative for measuring solution phase processes on the millisecond time-scale and a new, promising approach for revealing mechanistic details in (bio)chemical reactions.
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Affiliation(s)
- Tamanna Rob
- Department of Chemistry, York University, 4700 Keele St, Toronto, Ontario, M3J 1P3 Canada
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Ferguson CN, Benchaar SA, Miao Z, Loo JA, Chen H. Direct ionization of large proteins and protein complexes by desorption electrospray ionization-mass spectrometry. Anal Chem 2011; 83:6468-73. [PMID: 21774530 DOI: 10.1021/ac201390w] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Desorption electrospray ionization-mass spectrometry (DESI-MS) has advantages for rapid sample analysis with little or no sample pretreatment, but performance for large biomolecules has not been demonstrated. In this study, liquid sample DESI, an extended version of DESI used for analysis of liquid samples, was shown to have capabilities for direct ionization of large noncovalent protein complexes (>45 kDa) and proteins (up to 150 kDa). Protein complex ions (e.g., superoxide dismutase, enolase, and hemoglobin) desorbed from solution by liquid sample DESI were measured intact, indicating the capability of DESI for preserving weak noncovalent interactions. Doping the DESI spray solvent with supercharging reagents resulted in protein complex ions having increased multiple charging without complex dissociation. Ion mobility measurements of model protein cytochrome c showed that the supercharging reagent favored the more compact conformation for the lower charged protein ions. Liquid sample DESI of hydrophobic peptide gramicidin D suggests that the ionization mechanism involves a droplet pick-up mixing process. Measurement of liquid samples significantly extends the mass range of DESI-MS, allowing the analysis of high-mass proteins such as 150 kDa immunoglobulin G (IgG) and thus represents the largest protein successfully ionized by DESI to date.
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Affiliation(s)
- Carly N Ferguson
- Department of Chemistry and Biochemistry, David Geffen School of Medicine, University of California-Los Angeles, Los Angeles, California 90095, USA
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