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Coniglio D, Ventura G, Calvano CD, Losito I, Cataldi TRI. Positional Assignment of C-C Double Bonds in Fatty Acyl Chains of Intact Arsenosugar Phospholipids Occurring in Seaweed Extracts by Epoxidation Reactions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:823-831. [PMID: 35442668 DOI: 10.1021/jasms.2c00006] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Water-soluble diacyl arsenosugar phospholipids (As-PL) are natural products widespread in marine animals and algae, including the brown alga Undaria pinnatifida, also known as wakame. The systematic recognition of As-PL has been hampered by the lack of standard and of qualitative methods to establish the carbon-carbon double bond positions of unsaturated fatty acyl chains. Here, the epoxidation reaction of fatty acyl substituents of As-PL was carried out with high selectivity by meta-chloroperoxybenzoic acid and the C-C double bond localization was established by collision-induced dissociation of epoxidized species as deprotonated molecules, [epoM - H]-. Reversed-phase liquid chromatography (RPLC) separation and a sequential triple-stage MS (i.e., MS3) analysis of unsaturated and epoxidized As-PL were very helpful to characterize the carbon-carbon double bond locations of both sn-1 and sn-2 fatty acyl chains, starting from a diagnostic product ion pair with 16.0 Da mass difference. These results indicate that intact As-PL can be annotated in terms of fatty acyl chain composition and in terms of their C-C double bond position(s). Interestingly, hexadecenoic (16:1 Δ9) and octadecenoic (18:1 Δ9) along with octadecadienoic (18:2 Δ9,12) and octadecatrienoic (18:3 Δ9,12,15) were found to be the most abundant unsaturated fatty acyl chains of As-PL in the brown alga wakame, thus confirming it as a good source of essential fatty acids with a balanced ω6/ω3 ratio. Although the toxicity of As-including metabolites of algal As-PL is still a matter of debate and needs to be studied in more detail, the described approach can be exploited to assess if As-PL could contribute to the supply of essential fatty acids related to the use of algae as nutritious food.
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2
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Zhao J, Xie X, Lin Q, Ma X, Su P, Xia Y. Next-Generation Paternò–Büchi Reagents for Lipid Analysis by Mass Spectrometry. Anal Chem 2020; 92:13470-13477. [PMID: 32840355 DOI: 10.1021/acs.analchem.0c02896] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Jing Zhao
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xiaobo Xie
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Qiaohong Lin
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xiaoxiao Ma
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Pei Su
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Yu Xia
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
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3
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Makarieva TN, Ivanchina NV, Stonik VA. Application of Oxidative and Reductive Transformations in the Structure Determination of Marine Natural Products. JOURNAL OF NATURAL PRODUCTS 2020; 83:1314-1333. [PMID: 32091208 DOI: 10.1021/acs.jnatprod.9b01020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This review highlights the application of oxidative and reductive chemical transformations in the structure determination of complex marine natural products, including their absolute configurations. Workability of the Baeyer-Villiger reaction, ozonolysis, periodate oxidation, hydrogenolysis, and reductive amination, as well as other related chemical transformations, are discussed.
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Affiliation(s)
- Tatyana N Makarieva
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Pr. 100 let, Vladivostoku, 159, Russia
| | - Natalia V Ivanchina
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Pr. 100 let, Vladivostoku, 159, Russia
| | - Valentin A Stonik
- G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Pr. 100 let, Vladivostoku, 159, Russia
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4
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Klein DR, Blevins MS, Macias LA, Douglass MV, Trent MS, Brodbelt JS. Localization of Double Bonds in Bacterial Glycerophospholipids Using 193 nm Ultraviolet Photodissociation in the Negative Mode. Anal Chem 2020; 92:5986-5993. [PMID: 32212719 PMCID: PMC7385702 DOI: 10.1021/acs.analchem.0c00221] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The need for detailed structural characterization of glycerophospholipids (GPLs) for many types of biologically motivated applications has led to the development of novel mass spectrometry-based methodologies that utilize alternative ion activation methods. Ultraviolet photodissociation (UVPD) has shown great utility for localizing sites of unsaturation within acyl chains and to date has predominantly been used for positive mode analysis of GPLs. In the present work, UVPD is used to localize sites of unsaturation in GPL anions. Similar to UVPD mass spectra of GPL cations, UVPD of deprotonated or formate-adducted GPLs yields diagnostic fragment ions spaced 24 Da apart. This method was integrated into a liquid chromatography workflow and used to evaluate profiles of sites of unsaturation of lipids in Escherichia coli (E. coli) and Acinetobacter baumannii (A. baumannii). When assigning sites of unsaturation, E. coli was found to contain all unsaturation elements at the same position relative to the terminal methyl carbon of the acyl chain; the first carbon participating in a site of unsaturation was consistently seven carbons along the acyl chain when counting carbons from the terminal methyl carbon. GPLs from A. baumannii exhibited more variability in locations of unsaturation. For GPLs containing sites of unsaturation in both acyl chains, an MS3 method was devised to assign sites to specific acyl chains.
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Affiliation(s)
- Dustin R Klein
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Molly S Blevins
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Luis A Macias
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Martin V Douglass
- Department of Infectious Diseases, The University of Georgia, College of Veterinary Medicine, Athens, Georgia 30602, United States
| | - M Stephen Trent
- Department of Infectious Diseases, The University of Georgia, College of Veterinary Medicine, Athens, Georgia 30602, United States
- Department of Microbiology, The University of Georgia, College of Arts and Sciences, Athens, Georgia 30602, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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5
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Franklin ET, Shields SWJ, Manthorpe JM, Smith JC, Xia Y, McLuckey SA. Coupling Headgroup and Alkene Specific Solution Modifications with Gas-Phase Ion/Ion Reactions for Sensitive Glycerophospholipid Identification and Characterization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:938-945. [PMID: 32233382 PMCID: PMC7153167 DOI: 10.1021/jasms.0c00001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Shotgun lipidomics provides sensitive and fast lipid identification without the need for chromatographic separation. Challenges faced by shotgun analysis of glycerophospholipids (GPs) include the lack of signal uniformity across GP classes and the inability to determine the carbon-carbon double bond (C═C) location within the fatty acyl chains of an unsaturated species. Two distinct derivatization strategies were employed to both enhance the ionization of GPs, via trimethylation enhancement using 13C-diazomethane (13C-TrEnDi), as well as determine location of double bonds within fatty acyl chains, employing an in-solution photochemical reaction with acetone (via the Paternò-Büchi reaction). The modified GPs were then subjected to positive ion mode ionization via electrospray ionization, producing uniform ionization efficiencies for different classes of GP species. The GPs were charge inverted via gas-phase ion/ion reactions and sequentially fragmented using ion trap collision-induced dissociation (CID). The CID of the species led to fragmentation producing diagnostic ions indicative of C═C bond location. The approach enabled enhanced ionization and the identification of phosphatidylcholine and phosphatidylethanolamine species at the C═C level in a bovine lipid extract.
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Affiliation(s)
- Elissia T. Franklin
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, United States, 47907-2084, West Lafayette, IN, United States 47907-2084
| | - Samuel W. J. Shields
- Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Jeffrey M. Manthorpe
- Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Jeffrey C. Smith
- Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada
| | - Yu Xia
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, United States, 47907-2084, West Lafayette, IN, United States 47907-2084
- Department of Chemistry, Tsinghua University, Mengminwei Technical Building, Beijing, Haidian, China, 100084
| | - Scott A. McLuckey
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, United States, 47907-2084, West Lafayette, IN, United States 47907-2084
- Address reprint requests to Scott A. McLuckley, 560 Oval Drive, West Lafayette, IN, United States, 47907-2084, West Lafayette, IN, United States 47907-2084,
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6
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Cetraro N, Cody RB, Yew JY. Carbon-carbon double bond position elucidation in fatty acids using ozone-coupled direct analysis in real time mass spectrometry. Analyst 2019; 144:5848-5855. [PMID: 31482871 DOI: 10.1039/c9an01059a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The carbon-carbon double bond positions of unsaturated fatty acids can have markedly different effects on biological function and also serve as biomarkers of disease pathology, dietary history, and species identity. As such, there is great interest in developing methods for the facile determination of double bond position for natural product chemistry, the pharmaceutical industry, and forensics. We paired ozonolysis with direct analysis in real time mass spectrometry (DART MS) to cleave and rapidly identify carbon-carbon double bond position in fatty acids, fatty alcohols, wax esters, and crude fatty acid extracts. In addition, ozone exposure time and DART ion source temperature were investigated to identify optimal conditions. Our results reveal that brief, offline exposure to ozone-generated aldehyde and carboxylate products that are indicative of carbon-carbon double bond position. The relative abundance of diagnostic fragments quantitatively reflects the ratios of isobaric fatty acid positional isomers in a mixture with a correlation coefficient of 0.99. Lastly, the unsaturation profile generated from unfractionated, fatty acid extracts can be used to differentiate insect species and populations. The ability to rapidly elucidate lipid double bond position by combining ozonolysis with DART MS will be useful for lipid structural elucidation, assessing isobaric purity, and potentially distinguishing between animals fed on different diets or belonging to different ecological populations.
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Affiliation(s)
- Nicolas Cetraro
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, 1993 East West Road, Honolulu, USA 96822.
| | - Robert B Cody
- JEOL USA, Inc., 11 Dearborn Rd, Peabody, MA, USA 01960
| | - Joanne Y Yew
- Pacific Biosciences Research Center, University of Hawai'i at Mānoa, 1993 East West Road, Honolulu, USA 96822.
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7
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Song C, Gao D, Li S, Liu L, Chen X, Jiang Y. Determination and quantification of fatty acid C=C isomers by epoxidation reaction and liquid chromatography-mass spectrometry. Anal Chim Acta 2019; 1086:82-89. [PMID: 31561797 DOI: 10.1016/j.aca.2019.08.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 08/08/2019] [Accepted: 08/14/2019] [Indexed: 12/14/2022]
Abstract
The location of double bond in unsaturated fatty acids (FAs) plays a critical role in their physiological properties. However, structural identification and quantification of unsaturated FAs by mass spectrometry are still challenging. In this work, we reported the coupling of epoxidation reaction of the C=C in unsaturated FAs and liquid chromatography-mass spectrometry (LC-MS) with multiple reaction monitoring (MRM) mode for accurate identification and quantification of C=C isomers of FAs. Epoxidation of the C=C in unsaturated FAs was induced by a dioxide of ketone, tetrahydrothiopyran-4-one 1,1-dioxide, as a catalyst and Oxone as an oxidant in less than 5 min with nearly 100% yield. All the C=C bonds were epoxidized to obtain a single product, simplifying the chromatographic separation of epoxidation products to enable more accurate quantification analysis. The epoxidation products were stable at room temperature and can produce highly abundant diagnostic ions indicative of C=C locations by tandem mass spectrometry using collision-induced association (CID). The application of this approach for the analysis of FAs isomers in human plasma demonstrated the potential of our method for the qualitative and quantitative analysis of unsaturated FAs in complex biological samples, which is valuable in biological and medical analysis.
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Affiliation(s)
- Chao Song
- State Key Laboratory of Chemical Oncogenomics, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 518055, China
| | - Dan Gao
- State Key Laboratory of Chemical Oncogenomics, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 518055, China.
| | - Shangfu Li
- State Key Laboratory of Chemical Oncogenomics, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 518055, China
| | - Liping Liu
- Department of Hepatobiliary and Pancreatic Surgery, Shenzhen People's Hospital, Second Clinical Medical College of Jinan University, 1017 North of Dongmen Road, Shenzhen, Guangdong Province, 518000, China
| | - Xiaowu Chen
- Shenzhen Kivita Innovative Drug Discovery Institute, Shenzhen, 518110, China
| | - Yuyang Jiang
- State Key Laboratory of Chemical Oncogenomics, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 518055, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China.
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8
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Zhang W, Chiang S, Li Z, Chen Q, Xia Y, Ouyang Z. A Polymer Coating Transfer Enrichment Method for Direct Mass Spectrometry Analysis of Lipids in Biofluid Samples. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201900011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Wenpeng Zhang
- State Key Laboratory of Precision Measurement Technology and InstrumentsDepartment of Precision InstrumentTsinghua University Beijing 100084 China
- Department of Chemistry and Weldon School of Biomedical EngineeringPurdue University West Lafayette IN 47907 USA
| | - Spencer Chiang
- State Key Laboratory of Precision Measurement Technology and InstrumentsDepartment of Precision InstrumentTsinghua University Beijing 100084 China
- Department of Chemistry and Weldon School of Biomedical EngineeringPurdue University West Lafayette IN 47907 USA
| | - Zishuai Li
- State Key Laboratory of Precision Measurement Technology and InstrumentsDepartment of Precision InstrumentTsinghua University Beijing 100084 China
| | - Qinhua Chen
- Affiliated Dongfeng HospitalHubei University of Medicine Shiyan 442000 China
| | - Yu Xia
- Department of ChemistryTsinghua University Beijing 100084 China
| | - Zheng Ouyang
- State Key Laboratory of Precision Measurement Technology and InstrumentsDepartment of Precision InstrumentTsinghua University Beijing 100084 China
- Department of Chemistry and Weldon School of Biomedical EngineeringPurdue University West Lafayette IN 47907 USA
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9
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New Frontiers in Lipidomics Analyses using Structurally Selective Ion Mobility-Mass Spectrometry. Trends Analyt Chem 2019; 116:316-323. [PMID: 31983792 DOI: 10.1016/j.trac.2019.03.031] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The growth of lipidomics and the high isomeric complexity of the lipidome has revealed a need for analytical techniques capable of structurally characterizing lipids with a high degree of specificity. Lipids are morphologically diverse molecules that can exist as any one of a large number of isomeric species, and as such are often indistinguishable by mass spectrometry without a complementary separation method. Recent developments in the field of lipidomics aim to address these challenges by utilizing a combination of multiple analytical techniques which are selective to lipid primary structure. This review summarizes two emerging strategies for lipidomic analysis, namely, ion mobility-mass spectrometry and ion fragmentation via ozonolysis.
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10
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Zhang W, Chiang S, Li Z, Chen Q, Xia Y, Ouyang Z. A Polymer Coating Transfer Enrichment Method for Direct Mass Spectrometry Analysis of Lipids in Biofluid Samples. Angew Chem Int Ed Engl 2019; 58:6064-6069. [PMID: 30805967 DOI: 10.1002/anie.201900011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/16/2019] [Indexed: 12/17/2022]
Abstract
A porous polymer coating transfer enrichment method is developed for the direct mass spectrometry (MS) analysis of lipids. The enrichment is fast (ca. 1 min) and enables the profiling and quantitation of lipids in small-volume biofluid samples. Coupled with a photochemical Paternò-Büchi reaction, this method enables the fast determination of lipid structure at the C=C location level and point-of-care lipid biomarker analysis.
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Affiliation(s)
- Wenpeng Zhang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China.,Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Spencer Chiang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China.,Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Zishuai Li
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Qinhua Chen
- Affiliated Dongfeng Hospital, Hubei University of Medicine, Shiyan, 442000, China
| | - Yu Xia
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zheng Ouyang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China.,Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47907, USA
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11
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Franklin ET, Betancourt SK, Randolph CE, McLuckey SA, Xia Y. In-depth structural characterization of phospholipids by pairing solution photochemical reaction with charge inversion ion/ion chemistry. Anal Bioanal Chem 2019; 411:4739-4749. [PMID: 30613841 DOI: 10.1007/s00216-018-1537-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 11/25/2018] [Accepted: 12/03/2018] [Indexed: 11/25/2022]
Abstract
Shotgun lipid analysis based on electrospray ionization-tandem mass spectrometry (ESI-MS/MS) is increasingly used in lipidomic studies. One challenge for the shotgun approach is the discrimination of lipid isomers and isobars. Gas-phase charge inversion via ion/ion reactions has been used as an effective method to identify multiple isomeric/isobaric components in a single MS peak by exploiting the distinctive functionality of different lipid classes. In doing so, fatty acyl chain information can be obtained without recourse to condensed-phase separations or derivatization. This method alone, however, cannot provide carbon-carbon double bond (C=C) location information from fatty acyl chains. Herein, we provide an enhanced method pairing photochemical derivatization of C=C via the Paternò-Büchi reaction with charge inversion ion/ion tandem mass spectrometry. This method was able to provide gas-phase separation of phosphatidylcholines and phosphatidylethanolamines, the fatty acyl compositions, and the C=C location within each fatty acyl chain. We have successfully applied this method to bovine liver lipid extracts and identified 40 molecular species of glycerophospholipids with detailed structural information including head group, fatty acyl composition, and C=C location. Graphical Abstract ᅟ.
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Affiliation(s)
- Elissia T Franklin
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Stella K Betancourt
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Caitlin E Randolph
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Scott A McLuckey
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA.
| | - Yu Xia
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA.
- Department of Chemistry, Tsinghua University, Beijing, 100084, China.
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12
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Harris RA, May JC, Stinson CA, Xia Y, McLean JA. Determining Double Bond Position in Lipids Using Online Ozonolysis Coupled to Liquid Chromatography and Ion Mobility-Mass Spectrometry. Anal Chem 2018; 90:1915-1924. [PMID: 29341601 DOI: 10.1021/acs.analchem.7b04007] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The increasing focus on lipid metabolism has revealed a need for analytical techniques capable of structurally characterizing lipids with a high degree of specificity. Lipids can exist as any one of a large number of double bond positional isomers, which are indistinguishable by single-stage mass spectrometry alone. Ozonolysis reactions coupled to mass spectrometry have previously been demonstrated as a means for localizing double bonds in unsaturated lipids. Here we describe an online, solution-phase reactor using ozone produced via a low-pressure mercury lamp, which generates aldehyde products diagnostic of cleavage at a particular double bond position. This flow-cell device is utilized in conjunction with structurally selective ion mobility-mass spectrometry. The lamp-mediated reaction was found to be effective for multiple lipid species in both positive and negative ionization modes, and the conversion efficiency from precursor to product ions was tunable across a wide range (20-95%) by varying the flow rate through the ozonolysis device. Ion mobility separation of the ozonolysis products generated additional structural information and revealed the presence of saturated species in a complex mixture. The method presented here is simple, robust, and readily coupled to existing instrument platforms with minimal modifications necessary. For these reasons, application to standard lipidomic workflows is possible and aids in more comprehensive structural characterization of a myriad of lipid species.
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Affiliation(s)
- Rachel A Harris
- Department of Chemistry, Center for Innovative Technology, Vanderbilt Institute of Chemical Biology, Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Jody C May
- Department of Chemistry, Center for Innovative Technology, Vanderbilt Institute of Chemical Biology, Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University , Nashville, Tennessee 37235, United States
| | | | - Yu Xia
- Department of Chemistry, Tsinghua University , Beijing, China 100084
| | - John A McLean
- Department of Chemistry, Center for Innovative Technology, Vanderbilt Institute of Chemical Biology, Vanderbilt Institute for Integrative Biosystems Research and Education, Vanderbilt University , Nashville, Tennessee 37235, United States
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