1
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Li Y, Wang Y, Guo K, Tseng KF, Zhang X, Sun W. Aza-Prilezhaev Aziridination-Enabled Multidimensional Analysis of Isomeric Lipids via High-Resolution U-Shaped Mobility Analyzer-Mass Spectrometry. Anal Chem 2024; 96:7111-7119. [PMID: 38648270 DOI: 10.1021/acs.analchem.4c00481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Unsaturated lipids constitute a significant portion of the lipidome, serving as players of multifaceted functions involving cellular signaling, membrane structure, and bioenergetics. While derivatization-assisted liquid chromatography tandem mass spectrometry (LC-MS/MS) remains the gold standard technique in lipidome, it mainly faces challenges in efficiently labeling the carbon-carbon double bond (C═C) and differentiating isomeric lipids in full dimension. This presents a need for new orthogonal methodologies. Herein, a metal- and additive-free aza-Prilezhaev aziridination (APA)-enabled ion mobility mass spectrometric method is developed for probing multiple levels of unsaturated lipid isomerization with high sensitivity. Both unsaturated polar and nonpolar lipids can be efficiently labeled in the form of N-H aziridine without significant side reactions. The signal intensity can be increased by up to 3 orders of magnitude, achieving the nM detection limit. Abundant site-specific fragmentation ions indicate C═C location and sn-position in MS/MS spectra. Better yet, a stable monoaziridination product is dominant, simplifying the spectrum for lipids with multiple double bonds. Coupled with a U-shaped mobility analyzer, identification of geometric isomers and separation of different lipid classes can be achieved. Additionally, a unique pseudo MS3 mode with UMA-QTOF MS boosts the sensitivity for generating diagnostic fragments. Overall, the current method provides a comprehensive solution for deep-profiling lipidomics, which is valuable for lipid marker discovery in disease monitoring and diagnosis.
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Affiliation(s)
- Yuling Li
- Shimadzu Research Laboratory (Shanghai) Co., Ltd., Shanghai 201206, China
| | - Yiming Wang
- Shimadzu Research Laboratory (Shanghai) Co., Ltd., Shanghai 201206, China
| | - Kang Guo
- Shimadzu Research Laboratory (Shanghai) Co., Ltd., Shanghai 201206, China
| | - Kuo-Feng Tseng
- Shimadzu Research Laboratory (Shanghai) Co., Ltd., Shanghai 201206, China
| | - Xiaoqiang Zhang
- Shimadzu Research Laboratory (Shanghai) Co., Ltd., Shanghai 201206, China
| | - Wenjian Sun
- Shimadzu Research Laboratory (Shanghai) Co., Ltd., Shanghai 201206, China
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2
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Michael JA, Young RSE, Balez R, Jekimovs LJ, Marshall DL, Poad BLJ, Mitchell TW, Blanksby SJ, Ejsing CS, Ellis SR. Deep Characterisation of the sn-Isomer Lipidome Using High-Throughput Data-Independent Acquisition and Ozone-Induced Dissociation. Angew Chem Int Ed Engl 2024; 63:e202316793. [PMID: 38165069 DOI: 10.1002/anie.202316793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 12/12/2023] [Accepted: 12/27/2023] [Indexed: 01/03/2024]
Abstract
In recent years there has been a significant interest in the development of innovative lipidomics techniques capable of resolving lipid isomers. To date, methods applied to resolving sn-isomers have resolved only a limited number of species. We report a workflow based on ozone-induced dissociation for untargeted characterisation of hundreds of sn-resolved glycerophospholipid isomers from biological extracts in under 20 min, coupled with an automated data analysis pipeline. It provides an order of magnitude increase in the number of sn-isomer pairs identified as compared to previous reports and reveals that sn-isomer populations are tightly regulated and significantly different between cell lines. The sensitivity of this method and potential for de novo molecular discovery is further demonstrated by the identification of unexpected lipids containing ultra-long monounsaturated acyl chains at the sn-1 position.
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Affiliation(s)
- Jesse A Michael
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Reuben S E Young
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Rachelle Balez
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Lachlan J Jekimovs
- School of Chemistry and Physics and the Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - David L Marshall
- School of Chemistry and Physics and the Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - Berwyck L J Poad
- School of Chemistry and Physics and the Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - Todd W Mitchell
- Molecular Horizons and School of Medical, Indigenous and Health Sciences, University of Wollongong, Wollongong, NSW, Australia
| | - Stephen J Blanksby
- School of Chemistry and Physics and the Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD, 4000, Australia
| | - Christer S Ejsing
- Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Shane R Ellis
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
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3
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Sengupta A, Edwards ME, Yan X. Dual Metal Electrolysis in Theta Capillary for Lipid Analysis. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2023; 494:117137. [PMID: 38911479 PMCID: PMC11192522 DOI: 10.1016/j.ijms.2023.117137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/25/2024]
Abstract
Increasing studies associating glycerophospholipids with various pathological conditions highlight the need for their thorough characterization. However, the intricate composition of the lipidome due to the presence of lipid isomers poses significant challenges to structural lipidomics. This study uses the anodic corrosion of two metals in a single theta nESI emitter as a tool to simultaneously characterize lipids at multiple isomer levels. Anodic corrosion of cobalt and copper in the positive ion mode generates the metal-adducted lipid complexes, [M+Co]2+ and [M+Cu]+, respectively. Optimization of parameters such as the distances of the electrodes from the nESI tip allowed the achievement of the formation of one metal-adducted lipid product at a time. Collision-induced dissociation (CID) of [M+Co]2+ results in preferential loss of the fatty acyl (FA) chain at the sn-2 position, thus generating singly charged sn-specific fragment ions. Whereas, multistage fragmentation of [M+Cu]+ via CID generated a C=C bond position-specific characteristic ion pattern induced by the π-Cu+ interaction. The feasibility of the method was tested on PC lipid extract from egg yolk to identify lipids on multiple isomer levels. Thus, the application of dual metal anodic corrosion allows lipid isomer identification with reduced sample preparation time, no signal suppression by counter anions, low sample consumption, and no need for an extra apparatus.
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Affiliation(s)
- Annesha Sengupta
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Madison E. Edwards
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Xin Yan
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
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4
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Naylor CN, Nagy G. Permethylation and Metal Adduction: A Toolbox for the Improved Characterization of Glycolipids with Cyclic Ion Mobility Separations Coupled to Mass Spectrometry. Anal Chem 2023; 95:13725-13732. [PMID: 37650842 DOI: 10.1021/acs.analchem.3c03448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Lipids are an important class of molecules involved in various biological functions but remain difficult to characterize through mass-spectrometry-based methods because of their many possible isomers. Glycolipids, specifically, play important roles in cell signaling but display an even greater level of isomeric heterogeneity as compared to other lipid classes stemming from the introduction of a carbohydrate and its corresponding linkage position and α/β anomericity at the headgroup. While liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) remains the gold standard technique in lipidomics, it is still unable to characterize all isomeric species, thus presenting the need for new, orthogonal, methodologies. Ion mobility spectrometry-mass spectrometry (IMS-MS) can provide an additional dimension of information that supplements LC-MS/MS workflows, but has seen little use for glycolipid analyses. Herein, we present an analytical toolbox that enables the characterization of various glycolipid isomer sets using high-resolution cyclic ion mobility separations coupled with mass spectrometry (cIMS-MS). Specifically, we utilized a combination of both permethylation and metal adduction to fully resolve isomeric sphingolipids and ceramides with our cIMS-MS platform. We also introduce a new metric that can enable comparing peak-to-peak resolution across varying cIMS-MS pathlengths. Overall, we envision that our presented methodologies are highly amenable to existing LC-MS/MS-based workflows and can also have broad utility toward other omics-based analyses.
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Affiliation(s)
- Cameron N Naylor
- Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
| | - Gabe Nagy
- Department of Chemistry, University of Utah, 315 South 1400 East, Room 2020, Salt Lake City, Utah 84112, United States
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5
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Hormann FL, Sommer S, Heiles S. Formation and Tandem Mass Spectrometry of Doubly Charged Lipid-Metal Ion Complexes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023. [PMID: 37315187 DOI: 10.1021/jasms.3c00126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Phospholipids are major components of most eukaryotic cell membranes. Changes in metabolic states are often accompanied by phospholipid structure variations. The structural changes of phospholipids are the hallmark of disease states, or specific lipid structures have been associated with distinct organisms. Prime examples are microorganisms that synthesize phospholipids with, for example, different branched chain fatty acids. Assignment and relative quantitation of structural isomers of phospholipids that arise from attachment of different fatty acids to the glycerophospholipid backbone are difficult with routine tandem mass spectrometry or with liquid chromatography without authentic standards. In this work, we report on the observation that all investigated phospholipid classes form doubly charged lipid-metal ion complexes during electrospray ionization (ESI) and show that these complexes can be used to assign lipid classes and fatty acid moieties, distinguish isomers of branched chain fatty acids, and relatively quantify these isomers in positive-ion mode. Use of water free methanol and addition of divalent metal salts (100 mol %) to ESI spray solutions afford highly abundant doubly charged lipid-metal ion complexes (up to 70 times of protonated compounds). Higher-energy collisional dissociation and collision-induced dissociation of doubly charged complexes yield a diverse set of lipid class-dependent fragment ions. In common for all lipid classes is the liberation of fatty acid-metal adducts that yield fragment ions from the fatty acid hydrocarbon chain upon activation. This ability is used to pinpoint sites of branching in saturated fatty acids and is showcased for free fatty acids as well as glycerophospholipids. The analytical utility of doubly charged phospholipid-metal ion complexes is demonstrated by distinguishing fatty acid branching-site isomers in phospholipid mixtures and relatively quantifying the corresponding isomeric compounds.
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Affiliation(s)
- Felix-Levin Hormann
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Otto-Hahn-Straße 6b, 44139 Dortmund, Germany
- Lipidomics, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, 45141 Essen, Germany
| | - Simon Sommer
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Sven Heiles
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Otto-Hahn-Straße 6b, 44139 Dortmund, Germany
- Lipidomics, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, 45141 Essen, Germany
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6
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Freitas DP, Chen X, Hirtzel EA, Edwards ME, Kim J, Wang H, Sun Y, Kocurek KI, Russell D, Yan X. In situ droplet-based on-tissue chemical derivatization for lipid isomer characterization using LESA. Anal Bioanal Chem 2023:10.1007/s00216-023-04653-3. [PMID: 37017722 PMCID: PMC10392465 DOI: 10.1007/s00216-023-04653-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/03/2023] [Accepted: 03/14/2023] [Indexed: 04/06/2023]
Abstract
In this work, we present an in situ droplet-based derivatization method for fast tissue lipid profiling at multiple isomer levels. On-tissue derivatization for isomer characterization was achieved in a droplet delivered by the TriVersa NanoMate LESA pipette. The derivatized lipids were then extracted and analyzed by the automated chip-based liquid extraction surface analysis (LESA) mass spectrometry (MS) followed by tandem MS to produce diagnostic fragment ions to reveal the lipid isomer structures. Three reactions, i.e., mCPBA epoxidation, photocycloaddition catalyzed by the photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6, and Mn(II) lipid adduction, were applied using the droplet-based derivatization to provide lipid characterization at carbon-carbon double-bond positional isomer and sn-positional isomer levels. Relative quantitation of both types of lipid isomers was also achieved based on diagnostic ion intensities. This method provides the flexibility of performing multiple derivatizations at different spots in the same functional region of an organ for orthogonal lipid isomer analysis using a single tissue slide. Lipid isomers were profiled in the cortex, cerebellum, thalamus, hippocampus, and midbrain of the mouse brain and 24 double-bond positional isomers and 16 sn-positional isomers showed various distributions in those regions. This droplet-based derivatization of tissue lipids allows fast profiling of multi-level isomer identification and quantitation and has great potential in tissue lipid studies requiring rapid sample-to-result turnovers.
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Affiliation(s)
- Dallas P Freitas
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA
| | - Xi Chen
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA
| | - Erin A Hirtzel
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA
| | - Madison E Edwards
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA
| | - Joohan Kim
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA
| | - Hongying Wang
- Department of Nutrition, Texas A&M University, Carter-Mattil Hall, 373 Olven Blvd, College Station, TX, 77843, USA
| | - Yuxiang Sun
- Department of Nutrition, Texas A&M University, Carter-Mattil Hall, 373 Olven Blvd, College Station, TX, 77843, USA
| | - Klaudia I Kocurek
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA
| | - David Russell
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA
| | - Xin Yan
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX, 77843, USA.
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7
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Yan T, Born MEN, Prentice BM. Structural Elucidation and Relative Quantification of Sodium- and Potassium-Cationized Phosphatidylcholine Regioisomers Directly from Tissue Using Electron Induced Dissociation. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2023; 485:116998. [PMID: 37601139 PMCID: PMC10438893 DOI: 10.1016/j.ijms.2022.116998] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/22/2023]
Abstract
Comprehensive structural characterization of phosphatidylcholines (PCs) is essential to understanding their biological functions and roles in metabolism. Electron induced dissociation (EID) of protonated PCs directly generated from biological tissues has previously been shown to provide in-depth structural information on the lipid headgroup, regiosiomerism of fatty acyl tails and double bond positions. Although phosphatidylcholine ions formed via alkali metal cationization (i.e., [M + Na]+ and [M + K]+) are commonly generated during matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry experiments, the gas-phase ion chemistry behavior of EID on sodium- and potassium-cationized phosphatidylcholine ion types has not been studied for ions generated directly from tissue. Herein, we demonstrate EID on [M + Na]+ and [M + K]+ ion types in a MALDI imaging mass spectrometry workflow for lipid structural characterization. Briefly, near-complete structural information can be obtained upon EID of sodium- and potassium-cationized PCs, including diagnostic fragmentation of the lipid headgroup as well as identification of fatty acyl chain positions and double bond position. EID of cationized lipids generates sn-specific glycerol backbone cleavages as well as a favorable combined loss of sn-2 fatty acid with choline over sn-1, allowing for facile differentiation and relative quantification of PC regioisomers. Moreover, relative quantification of sn-positional isomers from biological tissue reveals that the relative percentages of sodium- and potassium-cationized sn-positional isomers varies significantly in different regions of rat brain tissue.
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Affiliation(s)
- Tingting Yan
- Department of Chemistry, University of Florida, Gainesville, FL 32611
| | | | - Boone M. Prentice
- Department of Chemistry, University of Florida, Gainesville, FL 32611
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8
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Jiao B, Zhou W, Liu Y, Zhang W, Ouyang Z. In-situ sampling of lipids in tissues using a porous membrane microprobe for direct mass spectrometry analysis. Mater Today Bio 2022; 16:100424. [PMID: 36157050 PMCID: PMC9490171 DOI: 10.1016/j.mtbio.2022.100424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/09/2022] [Accepted: 09/09/2022] [Indexed: 11/17/2022]
Abstract
Direct sampling of lipids from tissues for direct mass spectrometry (MS) analysis allows a quick profiling of lipidome, which is important for biomedical applications. In this work, we developed a polyporous polymeric membrane (PPM) microprobe for highly efficient sampling of lipids directly from tissue samples. The PPM was prepared by polypropylene with pores as large of 10 μm, facilitating the permeation of lipids from tissue surfaces. The PPM was coated onto a stainless steel wire with a thickness of ∼100 μm. The entire analysis procedure includes sampling of the lipids in tissue, washing the probe, and extraction spray ionization for MS analysis. The effectiveness was validated by analyzing mouse brain tissue samples. It showed high recoveries for a series of lipid classes in comparison with total lipid extraction method. Further demonstration was carried out with analysis of tissue samples from mouse liver, stomach, kidney and legs. With high physical strength and good chemical stability, the microprobe was also demonstrated for sampling lipids inside mouse kidney tissue samples. By incorporating a photochemical derivatization, a workflow was also developed for fast detection of lipid C
Created by potrace 1.16, written by Peter Selinger 2001-2019
]]>C isomers in tissue samples. Finally, a microprobe array was also developed for simultaneous sampling of lipids from multiple sites on tissue surfaces.
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9
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Chen X, Tang S, Freitas D, Hirtzel E, Cheng H, Yan X. Characterization of glycerophospholipids at multiple isomer levels via Mn(II)-catalyzed epoxidation. Analyst 2022; 147:4838-4844. [PMID: 36128870 PMCID: PMC9704799 DOI: 10.1039/d2an01174c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2023]
Abstract
Characterization of glycerophospholipid isomers is of significant importance as they play different roles in physiological and pathological processes. In this work, we present a novel and bifunctional derivatization method utilizing Mn(II)-catalyzed epoxidation to simultaneously identify carbon-carbon double bond (CC bond)- and stereonumbering (sn)-positional isomers of phosphatidylcholine. Mn(II) coordinates with picolinic acid and catalyzes epoxidation of unsaturated lipids by peracetic acid. Collision-induced dissociation (CID) of the epoxides generates diagnostic ions that can be used to locate CC bond positions. Meanwhile, CID of Mn(II) ion-lipid complexes produces characteristic ions for determination of sn positions. This bifunctional derivatization takes place in seconds, and the diagnostic ions produced in CID are clear and easy to interpret. Moreover, relative quantification of CC bond-and sn-positional isomers was achieved. The capability of this method in identifying lipids at multiple isomer levels was shown using lipid standards and lipid extracts from complex biological samples.
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Affiliation(s)
- Xi Chen
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX 77843, USA.
| | - Shuli Tang
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX 77843, USA.
| | - Dallas Freitas
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX 77843, USA.
| | - Erin Hirtzel
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX 77843, USA.
| | - Heyong Cheng
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX 77843, USA.
| | - Xin Yan
- Department of Chemistry, Texas A&M University, 580 Ross St, College Station, TX 77843, USA.
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10
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Yang T, Tang S, Kuo S, Freitas D, Edwards M, Wang H, Sun Y, Yan X. Lipid Mass Tags via Aziridination for Probing Unsaturated Lipid Isomers and Accurate Relative Quantification**. Angew Chem Int Ed Engl 2022; 61:e202207098. [DOI: 10.1002/anie.202207098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Tingyuan Yang
- Department of Chemistry Texas A&M University 580 Ross St. College Station TX 77843 USA
| | - Shuli Tang
- Department of Chemistry Texas A&M University 580 Ross St. College Station TX 77843 USA
| | - Syuan‐Ting Kuo
- Department of Chemistry Texas A&M University 580 Ross St. College Station TX 77843 USA
| | - Dallas Freitas
- Department of Chemistry Texas A&M University 580 Ross St. College Station TX 77843 USA
| | - Madison Edwards
- Department of Chemistry Texas A&M University 580 Ross St. College Station TX 77843 USA
| | - Hongying Wang
- Department of Nutrition Texas A&M University 373 Olsen Blvd. College Station TX 77845 USA
| | - Yuxiang Sun
- Department of Nutrition Texas A&M University 373 Olsen Blvd. College Station TX 77845 USA
| | - Xin Yan
- Department of Chemistry Texas A&M University 580 Ross St. College Station TX 77843 USA
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11
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Tang S, Chen X, Ke Y, Wang F, Yan X. Voltage-Controlled Divergent Cascade of Electrochemical Reactions for Characterization of Lipids at Multiple Isomer Levels Using Mass Spectrometry. Anal Chem 2022; 94:12750-12756. [PMID: 36087069 PMCID: PMC10386884 DOI: 10.1021/acs.analchem.2c02375] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cascading divergent reactions in a single system is highly desirable for their intrinsic efficiency and potential to achieve multilevel structural characterization of complex biomolecules. In this work, two electrochemical reactions, interfacial electro-epoxidation and cobalt anodic corrosion, are divergently cascaded in nanoelectrospray (nESI) and can be switched at different voltages. We applied these reactions to lipid identification at multiple isomer levels using mass spectrometry (MS), which remains a great challenge in structural lipidomics. The divergent cascade reactions in situ derivatize lipids to produce epoxidized lipids and cobalt-adducted lipids at different voltages. These lipids are then fragmented upon low-energy collision-induced dissociation (CID), generating diagnostic fragments to indicate C═C locations and sn-positions that cannot be achieved by the low-energy CID of native lipids. We have demonstrated that lipid structural isomers show significantly different profiles in the analysis of healthy and cancerous mouse prostate samples using this strategy. The application of divergent cascade reactions in lipid identification allows the four-in-one analysis of lipid headgroups, fatty acyl chains, C═C locations, and sn-positions simply by tuning the nESI voltages within a single experiment. This feature as well as its low sample consumption, no need for an extra apparatus, and quantitative analysis capability show its great potential in lipidomics.
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Affiliation(s)
- Shuli Tang
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
| | - Xi Chen
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
| | - Yuepeng Ke
- Center for Translational Cancer Research, Texas A&M Institute of Biosciences and Technology, Texas A&M University, Houston, Texas 77030, United States
| | - Fen Wang
- Center for Translational Cancer Research, Texas A&M Institute of Biosciences and Technology, Texas A&M University, Houston, Texas 77030, United States
| | - Xin Yan
- Department of Chemistry, Texas A&M University, 580 Ross Street, College Station, Texas 77843, United States
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12
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Kuo ST, Tang S, Russell DH, Yan X. Characterization of lipid carbon-carbon double-bond isomerism via ion mobility-mass spectrometry (IMS-MS) combined with cuprous ion-induced fragmentation. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY 2022; 479:116889. [PMID: 37577146 PMCID: PMC10421641 DOI: 10.1016/j.ijms.2022.116889] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Characterization of phospholipid isomers is challenging due to their identical masses and similarities in structures. Here, we report that copper (I) ion complexed with phospholipids can be used to characterize both carbon-carbon double-bond (C=C bond) positional and geometric isomers. We investigate the distinct fragmentation patterns induced by the π-Cu+ interaction and developed strategies to rapidly characterize the isomerism of phospholipids. The multi-stage fragmentation of Cu+-adducted lipids by collision-induced dissociation can generate diagnostic ions to locate C=C bonds in unsaturated lipids. Furthermore, the collision cross sections of Cu+-adducted parent lipids and product ions can be used as molecular descriptors in distinguishing C=C bond geometric isomers. A bovine heart lipid extract containing Z-configuration lipids spiked with an E-configuration lipid was analyzed to demonstrate rapidness and effectiveness of the method in distinguishing lipid geometric isomers from a real sample.
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Affiliation(s)
| | | | - David H. Russell
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
| | - Xin Yan
- Department of Chemistry, Texas A&M University, College Station, TX, 77843, USA
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13
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Shields SWJ, Sanders JD, Brodbelt JS. Enhancing the Signal-to-Noise of Diagnostic Fragment Ions of Unsaturated Glycerophospholipids via Precursor Exclusion Ultraviolet Photodissociation Mass Spectrometry (PEx-UVPD-MS). Anal Chem 2022; 94:11352-11359. [PMID: 35917227 PMCID: PMC9484799 DOI: 10.1021/acs.analchem.2c02128] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding and elucidating the diverse structures and functions of lipids has motivated the development of many innovative tandem mass spectrometry (MS/MS) strategies. Higher-energy activation methods, such as ultraviolet photodissociation (UVPD), generate unique fragment ions from glycerophospholipids that can be used to perform in-depth structural analysis and facilitate the deconvolution of isomeric lipid structures in complex samples. Although detailed characterization is central to the correlation of lipid structure to biological function, it is often impeded by the lack of sufficient instrument sensitivity for highly bioactive but low-abundance phospholipids. Here, we present precursor exclusion (PEx) UVPD, a simple yet powerful technique to enhance the signal-to-noise (S/N) of informative low-abundance fragment ions produced from UVPD of glycerophospholipids. Through the exclusion of the large population of undissociated precursor ions with an MS3 strategy, the S/N of diagnostic fragment ions from PC 18:0/18:2(9Z, 12Z) increased up to an average of 13x for PEx-UVPD compared to UVPD alone. These enhancements were extended to complex mixtures of lipids from bovine liver extract to confidently identify 35 unique structures using liquid chromatography PEx-UVPD. This methodology has the potential to advance lipidomics research by offering deeper structure elucidation and confident identification of biologically active lipids.
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Affiliation(s)
- Samuel W J Shields
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - James D Sanders
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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14
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Yang T, Tang S, Kuo ST, Freitas D, Edwards M, Wang H, Sun Y, Yan X. Lipid Mass Tags via Aziridination for Probing Unsaturated Lipid Isomers and Accurate Relative Quantification. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Shuli Tang
- Texas A&M University Chemistry UNITED STATES
| | | | | | | | - Hongying Wang
- Texas A&M University Department of Nutrition UNITED STATES
| | - Yuxiang Sun
- Texas A&M University Department of Nutrition UNITED STATES
| | - Xin Yan
- Texas A&M University Chemistry 580 Ross St 77840 College Station UNITED STATES
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15
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Quantitative determination of sn-positional phospholipid isomers in MS n using silver cationization. Anal Bioanal Chem 2022; 414:7473-7482. [PMID: 35731255 PMCID: PMC9482905 DOI: 10.1007/s00216-022-04173-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/13/2022] [Accepted: 06/09/2022] [Indexed: 11/18/2022]
Abstract
Glycerophospholipids are one of the fundamental building blocks for life. The acyl chain connectivity to the glycerol backbone constitutes different sn-positional isomers, which have great diversity and importance for biological function. However, to fully realize their impact on function, analytical techniques that can identify and quantify sn-positional isomers in chemically complex biological samples are needed. Here, we utilize silver ion cationization in combination with tandem mass spectrometry (MSn) to identify sn-positional isomers of phosphatidylcholine (PC) species. In particular, a labile carbocation is generated through a neutral loss (NL) of AgH, the dissociation of which provides diagnostic product ions that correspond to acyl chains at the sn-1 or sn-2 position. The method is comparable to currently available methods, has a sensitivity in the nM–µM range, and is compatible with quantitative imaging using mass spectrometry in MS4. The results reveal a large difference in isomer concentrations and the ion images show that the sn-positional isomers PC 18:1_18:0 are homogeneously distributed, whereas PC 18:1_16:0 and PC 20:1_16:0 show distinct localizations to sub-hippocampal structures.
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16
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Zhang W, Jian R, Zhao J, Liu Y, Xia Y. Deep-lipidotyping by mass spectrometry: recent technical advances and applications. J Lipid Res 2022; 63:100219. [PMID: 35489417 PMCID: PMC9213770 DOI: 10.1016/j.jlr.2022.100219] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 12/18/2022] Open
Abstract
In-depth structural characterization of lipids is an essential component of lipidomics. There has been a rapid expansion of mass spectrometry methods that are capable of resolving lipid isomers at various structural levels over the past decade. These developments finally make deep-lipidotyping possible, which provides new means to study lipid metabolism and discover new lipid biomarkers. In this review, we discuss recent advancements in tandem mass spectrometry (MS/MS) methods for identification of complex lipids beyond the species (known headgroup information) and molecular species (known chain composition) levels. These include identification at the levels of carbon-carbon double bond (C=C) location and sn-position as well as characterization of acyl chain modifications. We also discuss the integration of isomer-resolving MS/MS methods with different lipid analysis workflows and their applications in lipidomics. The results showcase the distinct capabilities of deep-lipidotyping in untangling the metabolism of individual isomers and sensitive phenotyping by using relative fractional quantitation of the isomers.
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Affiliation(s)
- Wenpeng Zhang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, P. R. China
| | - Ruijun Jian
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biological, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Jing Zhao
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biological, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
| | - Yikun Liu
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, P. R. China
| | - Yu Xia
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biological, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.
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17
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Macias LA, Brodbelt JS. Enhanced Characterization of Cardiolipins via Hybrid 193 nm Ultraviolet Photodissociation Mass Spectrometry. Anal Chem 2022; 94:3268-3277. [PMID: 35135194 PMCID: PMC9284920 DOI: 10.1021/acs.analchem.1c05071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cardiolipins (CLs) constitute a structurally complex class of glycerophospholipids with a unique tetraacylated structure accompanied by distinctive functional roles. Aberrations in the composition of this lipid class have been associated with disease states, spurring interest in the development of new approaches to differentiate the structures of diverse CLs in complex mixtures. The structural characterization of these complex lipids using conventional methods, however, suffers from limited resolution and frequently proves unable to discern subtle yet biologically significant features such as unsaturation sites or acyl chain position assignments. Here, we describe the synergistic use of chemical derivatization and hybrid dissociation techniques to characterize CL from complex biological mixtures with both double bond and sn positional isomer resolution in a shotgun mass spectrometry strategy. Utilizing (trimethylsilyl)diazomethane (TMSD), CL phosphate groups were methylated to promote positive-mode ionization by the production of metal-cationized lipids, enabling structural interrogation via hybrid higher-energy collisional activation/ultraviolet photodissociation (HCD/UVPD). This combination of TMSD derivatization and HCD/UVPD fragmentation results in diagnostic product ions that permit distinction and relative quantitation of sn-stereoisomers and the localization of double bonds. Applying this strategy to a total lipid extract from a thyroid carcinoma revealed a previously unreported 18:2/18:1 motif, elucidating a structural feature unique to the lipid class.
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Affiliation(s)
- Luis A. Macias
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jennifer S. Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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18
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Kirschbaum C, Greis K, Gewinner S, Schöllkopf W, Meijer G, von Helden G, Pagel K. Cryogenic infrared spectroscopy provides mechanistic insight into the fragmentation of phospholipid silver adducts. Anal Bioanal Chem 2022; 414:5275-5285. [PMID: 35147717 PMCID: PMC9242943 DOI: 10.1007/s00216-022-03927-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/07/2022] [Accepted: 01/25/2022] [Indexed: 11/25/2022]
Abstract
Tandem mass spectrometry is arguably the most important analytical tool for structure elucidation of lipids and other metabolites. By fragmenting intact lipid ions, valuable structural information such as the lipid class and fatty acyl composition are readily obtainable. The information content of a fragment spectrum can often be increased by the addition of metal cations. In particular, the use of silver ions is deeply rooted in the history of lipidomics due to their propensity to coordinate both electron-rich heteroatoms and C = C bonds in aliphatic chains. Not surprisingly, coordination of silver ions was found to enable the distinction of sn-isomers in glycerolipids by inducing reproducible intensity differences in the fragment spectra, which could, however, not be rationalized. Here, we investigate the fragmentation behaviors of silver-adducted sn- and double bond glycerophospholipid isomers by probing fragment structures using cryogenic gas-phase infrared (IR) spectroscopy. Our results confirm that neutral headgroup loss from silver-adducted glycerophospholipids leads to dioxolane-type fragments generated by intramolecular cyclization. By combining high-resolution IR spectroscopy and computational modelling of silver-adducted fragments, we offer qualitative explanations for different fragmentation behaviors of glycerophospholipid isomers. Overall, the results demonstrate that gas-phase IR spectroscopy of fragment ions can significantly contribute to our understanding of lipid dissociation mechanisms and the influence of coordinating cations.
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Affiliation(s)
- Carla Kirschbaum
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195, Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195, Berlin, Germany
| | - Kim Greis
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195, Berlin, Germany
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195, Berlin, Germany
| | - Sandy Gewinner
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195, Berlin, Germany
| | - Wieland Schöllkopf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195, Berlin, Germany
| | - Gerard Meijer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195, Berlin, Germany
| | - Gert von Helden
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195, Berlin, Germany
| | - Kevin Pagel
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195, Berlin, Germany.
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195, Berlin, Germany.
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19
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Becher S, Berden G, Martens J, Oomens J, Heiles S. IRMPD Spectroscopy of [PC (4:0/4:0) + M] + (M = H, Na, K) and Corresponding CID Fragment Ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:2874-2884. [PMID: 34723538 DOI: 10.1021/jasms.1c00277] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Glycerophospholipids (GPs) are highly abundant in eukaryotic cells and take part in numerous fundamental physiological processes such as molecular signaling. The GP composition of samples is often analyzed using mass spectrometry (MS), but identification of some structural features, for example, differentiation of stereospecific numbering (sn) isomers by well-established tandem MS (MS2) methods, is challenging. In particular, the formation of 1,3-dioxolane over 1,3-dioxane intermediates proposed to be responsible for the sn-selectivity of these tandem MS strategies has not been validated by spectroscopic methods. In this work, we present infrared multiple photon dissociation (IRMPD) spectra of phosphatidylcholine (PC) ions [PC 4:0/4:0 + H/Na/K]+ and [PC 4:0/4:0 + Na/K - 183]+ fragments generated by electrospray ionization (ESI)-MS and collision-induced dissociation (CID), respectively. IRMPD spectra of protonated, sodiated, and potassiated PC 4:0/4:0 differ in the phosphate- and ester-related bands, which are increasingly shifted to lower wavenumbers with higher adduct masses. Comparison of calculated and experimental IR spectra indicates the presence of multiple, two and one isomer(s) for [PC 4:0/4:0 + H]+, [PC 4:0/4:0 + Na]+, and [PC 4:0/4:0 + K]+, respectively. Isomers exhibiting pronounced sn-1 ester-ion interactions are computationally predicted to be energetically preferred for all species and are in line with experimental results. IRMPD spectra of [PC 4:0/4:0 + Na/K - 183]+ are presented and shed the first light on the fragment ion structures, rationalizing MS-based lipidomics strategies that aim to characterize the sn-isomerism of GPs.
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Affiliation(s)
- Simon Becher
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Giel Berden
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - Jonathan Martens
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - Jos Oomens
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
| | - Sven Heiles
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, 35392 Giessen, Germany
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20
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Heiles S. Advanced tandem mass spectrometry in metabolomics and lipidomics-methods and applications. Anal Bioanal Chem 2021; 413:5927-5948. [PMID: 34142202 PMCID: PMC8440309 DOI: 10.1007/s00216-021-03425-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/11/2021] [Accepted: 05/19/2021] [Indexed: 12/11/2022]
Abstract
Metabolomics and lipidomics are new drivers of the omics era as molecular signatures and selected analytes allow phenotypic characterization and serve as biomarkers, respectively. The growing capabilities of untargeted and targeted workflows, which primarily rely on mass spectrometric platforms, enable extensive charting or identification of bioactive metabolites and lipids. Structural annotation of these compounds is key in order to link specific molecular entities to defined biochemical functions or phenotypes. Tandem mass spectrometry (MS), first and foremost collision-induced dissociation (CID), is the method of choice to unveil structural details of metabolites and lipids. But CID fragment ions are often not sufficient to fully characterize analytes. Therefore, recent years have seen a surge in alternative tandem MS methodologies that aim to offer full structural characterization of metabolites and lipids. In this article, principles, capabilities, drawbacks, and first applications of these "advanced tandem mass spectrometry" strategies will be critically reviewed. This includes tandem MS methods that are based on electrons, photons, and ion/molecule, as well as ion/ion reactions, combining tandem MS with concepts from optical spectroscopy and making use of derivatization strategies. In the final sections of this review, the first applications of these methodologies in combination with liquid chromatography or mass spectrometry imaging are highlighted and future perspectives for research in metabolomics and lipidomics are discussed.
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Affiliation(s)
- Sven Heiles
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, Heinrich Buff Ring 17, 35392, Giessen, Germany.
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21
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Kirschbaum C, Greis K, Polewski L, Gewinner S, Schöllkopf W, Meijer G, von Helden G, Pagel K. Unveiling Glycerolipid Fragmentation by Cryogenic Infrared Spectroscopy. J Am Chem Soc 2021; 143:14827-14834. [PMID: 34473927 PMCID: PMC8447261 DOI: 10.1021/jacs.1c06944] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
Mass spectrometry
is routinely employed for structure elucidation
of molecules. Structural information can be retrieved from intact
molecular ions by fragmentation; however, the interpretation of fragment
spectra is often hampered by poor understanding of the underlying
dissociation mechanisms. For example, neutral headgroup loss from
protonated glycerolipids has been postulated to proceed via an intramolecular
ring closure but the mechanism and resulting ring size have never
been experimentally confirmed. Here we use cryogenic gas-phase infrared
(IR) spectroscopy in combination with computational chemistry to unravel
the structures of fragment ions and thereby shed light on elusive
dissociation mechanisms. Using the example of glycerolipid fragmentation,
we study the formation of protonated five-membered dioxolane and six-membered
dioxane rings and show that dioxolane rings are predominant throughout
different glycerolipid classes and fragmentation channels. For comparison,
pure dioxolane and dioxane ions were generated from tailor-made dehydroxyl
derivatives inspired by natural 1,2- and 1,3-diacylglycerols and subsequently
interrogated using IR spectroscopy. Furthermore, the cyclic structure
of an intermediate fragment occurring in the phosphatidylcholine fragmentation
pathway was spectroscopically confirmed. Overall, the results contribute
substantially to the understanding of glycerolipid fragmentation and
showcase the value of vibrational ion spectroscopy to mechanistically
elucidate crucial fragmentation pathways in lipidomics.
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Affiliation(s)
- Carla Kirschbaum
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany.,Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | - Kim Greis
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany.,Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | - Lukasz Polewski
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany.,Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | - Sandy Gewinner
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | | | - Gerard Meijer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | - Gert von Helden
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
| | - Kevin Pagel
- Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany.,Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany
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22
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Macias LA, Garza KY, Feider CL, Eberlin LS, Brodbelt JS. Relative Quantitation of Unsaturated Phosphatidylcholines Using 193 nm Ultraviolet Photodissociation Parallel Reaction Monitoring Mass Spectrometry. J Am Chem Soc 2021; 143:14622-14634. [PMID: 34486374 PMCID: PMC8579512 DOI: 10.1021/jacs.1c05295] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Structural characterization of glycerophospholipids beyond the fatty acid level has become a major endeavor in lipidomics, presenting an opportunity to advance the understanding of the intricate relationship between lipid metabolism and disease state. Distinguishing subtle lipid structural features, however, remains a major challenge for high-throughput workflows that implement traditional tandem mass spectrometry (MS/MS) techniques, stunting the molecular depth of quantitative strategies. Here, reversed phase liquid chromatography is coupled to parallel reaction mass spectrometry utilizing the double bond localization capabilities of ultraviolet photodissociation (UVPD) mass spectrometry to produce double bond isomer specific responses that are leveraged for relative quantitation. The strategy provides lipidomic characterization at the double bond level for phosphatidylcholine phospholipids from biological extracts. In addition to quantifying monounsaturated lipids, quantitation of phospholipids incorporating isomeric polyunsaturated fatty acids is also achieved. Using this technique, phosphatidylcholine isomer ratios are compared across human normal and tumor breast tissue to reveal significant structural alterations related to disease state.
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Affiliation(s)
- Luis A Macias
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Kyana Y Garza
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Clara L Feider
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Livia S Eberlin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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23
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Becher S, Wang H, Leeming MG, Donald WA, Heiles S. Influence of protein ion charge state on 213 nm top-down UVPD. Analyst 2021; 146:3977-3987. [PMID: 34009215 DOI: 10.1039/d1an00571e] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ultraviolet photodissociation (UVPD) is a powerful and rapidly developing method in top-down proteomics. Sequence coverages can exceed those obtained with collision- and electron-induced fragmentation methods. Because of the recent interest in UVPD, factors that influence protein fragmentation and sequence coverage are actively debated in the literature. Here, we performed top-down 213 nm UVPD experiments on a 7 T Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR MS) for the model proteins ubiquitin, myoglobin and cytochrome c that were electrosprayed from native, denaturing and supercharging solutions in order to investigate the effect of protein charge states on UVPD fragments. By performing UVPD in ultrahigh vacuum, factors associated with collisional cooling and any ion activation during transfer between mass analyzers can be largely eliminated. Sequence coverage increased from <10% for low charge states to >60% for high charge states for all three proteins. This trend is influenced by the overall charge state, i.e., charges per number of amino acid residues, and to a lesser degree by associated structural changes of protein ions of different charge states based on comparisons to published collision-cross section measurements. To rationalize this finding, and correlate sequence ion formation and identity with the number and location of protons, UVPD results were compared to protonation sites predicted based on electrostatic modelling. Assuming confined protonation sites, these results indicate the presence of two general fragmentation types; i.e., charge remote and charge directed. For moderately high protein charge states, fragment ions mostly originate in regions between likely protonation sites (charge remote), whereas sequence ions of highly charge protein ions occur either near backbone amide protonation sites at low-basicity residues (charge directed) or at charge remote sites (i.e., high-basicity residues). Overall, our results suggest that top-down 213 UVPD performance in the zero-pressure limit depends strongly on protein charge states and protonation sites can influence the location of backbone cleavages.
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Affiliation(s)
- Simon Becher
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, 35392 Giessen, Germany.
| | - Huixin Wang
- Mark Wainwright Analytical Centre, University of New South Wales, New South Wales, Australia
| | - Michael G Leeming
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria, Australia
| | - William A Donald
- School of Chemistry, University of New South Wales, Sydney, New South Wales, Australia
| | - Sven Heiles
- Institute of Inorganic and Analytical Chemistry, Justus Liebig University Giessen, 35392 Giessen, Germany.
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24
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Zhao X, Xia Y. Characterization of Fatty Acyl Modifications in Phosphatidylcholines and Lysophosphatidylcholines via Radical-Directed Dissociation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:560-568. [PMID: 33444004 DOI: 10.1021/jasms.0c00407] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Phosphatidylcholines (PCs) are the major structural components of the plasma membrane of mammalian cells, while lysophosphatidylcholines (LPCs) are critical intermediates in lipid remodeling. Conventional tandem mass spectrometric (MSn) methods via collision-induced dissociation (CID) are blind to intrachain modifications such as the location of the carbon-carbon double bond (C═C) and methyl branching point. In this study, we demonstrate that almost complete structural information can be inferred from a single MS2 CID spectrum of the bicarbonate anion adducts of PC or LPC ([M + HCO3]-), including the identity of the headgroup, composition of fatty acyl chains, their sn-positions, the location of C═C, and the point of methyl branching in fatty acyls. We have integrated this MS2 CID method onto liquid chromatography for the analysis LPCs in human plasma, revealing the existence of multiple sn-isomers, branched chain isomers, and C═C location isomers of LPC.
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Affiliation(s)
- Xue Zhao
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yu Xia
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
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25
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Randolph CE, Blanksby SJ, McLuckey SA. Enhancing detection and characterization of lipids using charge manipulation in electrospray ionization-tandem mass spectrometry. Chem Phys Lipids 2020; 232:104970. [PMID: 32890498 PMCID: PMC7606777 DOI: 10.1016/j.chemphyslip.2020.104970] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/25/2020] [Accepted: 08/31/2020] [Indexed: 12/14/2022]
Abstract
Heightened awareness regarding the implication of disturbances in lipid metabolism with respect to prevalent human-related pathologies demands analytical techniques that provide unambiguous structural characterization and accurate quantitation of lipids in complex biological samples. The diversity in molecular structures of lipids along with their wide range of concentrations in biological matrices present formidable analytical challenges. Modern mass spectrometry (MS) offers an unprecedented level of analytical power in lipid analysis, as many advancements in the field of lipidomics have been facilitated through novel applications of and developments in electrospray ionization tandem mass spectrometry (ESI-MS/MS). ESI allows for the formation of intact lipid ions with little to no fragmentation and has become widely used in contemporary lipidomics experiments due to its sensitivity, reproducibility, and compatibility with condensed-phase modes of separation, such as liquid chromatography (LC). Owing to variations in lipid functional groups, ESI enables partial chemical separation of the lipidome, yet the preferred ion-type is not always formed, impacting lipid detection, characterization, and quantitation. Moreover, conventional ESI-MS/MS approaches often fail to expose diverse subtle structural features like the sites of unsaturation in fatty acyl constituents or acyl chain regiochemistry along the glycerol backbone, representing a significant challenge for ESI-MS/MS. To overcome these shortcomings, various charge manipulation strategies, including charge-switching, have been developed to transform ion-type and charge state, with aims of increasing sensitivity and selectivity of ESI-MS/MS approaches. Importantly, charge manipulation approaches afford enhanced ionization efficiency, improved mixture analysis performance, and access to informative fragmentation channels. Herein, we present a critical review of the current suite of solution-based and gas-phase strategies for the manipulation of lipid ion charge and type relevant to ESI-MS/MS.
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Affiliation(s)
- Caitlin E Randolph
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA
| | - Stephen J Blanksby
- Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology, Brisbane, QLD 4000, Australia
| | - Scott A McLuckey
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, USA.
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26
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Buenger EW, Reid GE. Shedding light on isomeric FAHFA lipid structures using 213 nm ultraviolet photodissociation mass spectrometry. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2020; 26:311-323. [PMID: 32957827 DOI: 10.1177/1469066720960341] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fatty Acid Esters of Hydroxy Fatty Acids (FAHFAs) are a recently discovered class of biological active lipids with anti-diabetic and anti-inflammatory functions. Given that structure and function are intimately related, we report here the use of direct infusion multi-stage hybrid tandem mass spectrometry involving sequential Collisional Activated Dissociation (CAD) and 213 nm UltraViolet PhotoDissociation (UVPD), as a novel technique for the unambiguous denovo identification and detailed structural characterisation of FAHFA lipid ions, including determination of the esterified fatty acid identity, the hydroxy fatty acid identity and position of esterification, and localization of the site(s) of endogenous unsaturations, without need for chromatographic separation or authentic reference standards. The utility of this approach is demonstrated for the identification of individual FAHFA lipids introduced to the mass spectrometer in positive ionization mode as their lithiated adducts, as well as from mixtures containing isomeric FAHFA species with differing esterification sites, including those that are not resolved by current liquid chromatography methods.
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Affiliation(s)
| | - Gavin E Reid
- School of Chemistry, The University of Melbourne, Parkville, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Australia
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27
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Blevins MS, James VK, Herrera CM, Purcell AB, Trent MS, Brodbelt JS. Unsaturation Elements and Other Modifications of Phospholipids in Bacteria: New Insight from Ultraviolet Photodissociation Mass Spectrometry. Anal Chem 2020; 92:9146-9155. [PMID: 32479092 PMCID: PMC7384744 DOI: 10.1021/acs.analchem.0c01449] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Glycerophospholipids (GPLs), one of the main components of bacterial cell membranes, exhibit high levels of structural complexity that are directly correlated with biophysical membrane properties such as permeability and fluidity. This structural complexity arises from the substantial variability in the individual GPL structural components such as the acyl chain length and headgroup type and is further amplified by the presence of modifications such as double bonds and cyclopropane rings. Here we use liquid chromatography coupled to high-resolution and high-mass-accuracy ultraviolet photodissociation mass spectrometry for the most in-depth study of bacterial GPL modifications to date. In doing so, we unravel a diverse array of unexplored GPL modifications, ranging from acyl chain hydroxyl groups to novel headgroup structures. Along with characterizing these modifications, we elucidate general trends in bacterial GPL unsaturation elements and thus aim to decipher some of the biochemical pathways of unsaturation incorporation in bacterial GPLs. Finally, we discover aminoacyl-PGs not only in Gram-positive bacteria but also in Gram-negative C. jejuni, advancing our knowledge of the methods of surface charge modulation that Gram-negative organisms may adopt for antibiotic resistance.
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Affiliation(s)
- Molly S Blevins
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Virginia K James
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Carmen M Herrera
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, United States
| | - Alexandria B Purcell
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, United States
| | - M Stephen Trent
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, United States
- Department of Microbiology, College of Arts and Sciences, University of Georgia, Athens, Georgia 30602, United States
- Center for Vaccines and Immunology, University of Georgia, Athens, Georgia 30602, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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Feider CL, Macias LA, Brodbelt JS, Eberlin LS. Double Bond Characterization of Free Fatty Acids Directly from Biological Tissues by Ultraviolet Photodissociation. Anal Chem 2020; 92:8386-8395. [PMID: 32421308 PMCID: PMC7433749 DOI: 10.1021/acs.analchem.0c00970] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Free fatty acids (FA) are a vital component of cells and are critical to cellular structure and function, so much so that alterations in FA are often associated with cell malfunction and disease. Analysis of FA from biological samples can be achieved by mass spectrometry (MS), but these analyses are often not capable of distinguishing the fine structural alterations within FA isomers and often limited to global profiling of lipids without spatial resolution. Here, we present the use of ultraviolet photodissociation (UVPD) for the characterization of double bond positional isomers of charge inverted dication·FA complexes and the subsequent implementation of this method for online desorption electrospray ionization (DESI) MS imaging of FA isomers from human tissue sections. This method allows relative quantification of FA isomers from heterogeneous biological tissue sections, yielding spatially resolved information about alterations in double bond isomers within these samples. Applying this method to the analysis of the monounsaturated FA 18:1 within breast cancer subtypes uncovered a correlation between double bond positional isomer abundance and the hormone receptor status of the tissue sample, an important factor in the prognosis and treatment of breast cancer patients. This result further validates similar studies that suggest FA synthase activity and FA isomer abundances are significantly altered within breast cancer tissue.
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Affiliation(s)
- Clara L Feider
- 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
| | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Livia S Eberlin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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29
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Brodbelt JS, Morrison LJ, Santos I. Ultraviolet Photodissociation Mass Spectrometry for Analysis of Biological Molecules. Chem Rev 2020; 120:3328-3380. [PMID: 31851501 PMCID: PMC7145764 DOI: 10.1021/acs.chemrev.9b00440] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of new ion-activation/dissociation methods continues to be one of the most active areas of mass spectrometry owing to the broad applications of tandem mass spectrometry in the identification and structural characterization of molecules. This Review will showcase the impact of ultraviolet photodissociation (UVPD) as a frontier strategy for generating informative fragmentation patterns of ions, especially for biological molecules whose complicated structures, subtle modifications, and large sizes often impede molecular characterization. UVPD energizes ions via absorption of high-energy photons, which allows access to new dissociation pathways relative to more conventional ion-activation methods. Applications of UVPD for the analysis of peptides, proteins, lipids, and other classes of biologically relevant molecules are emphasized in this Review.
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Affiliation(s)
- Jennifer S. Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Lindsay J. Morrison
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Inês Santos
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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30
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Cao W, Cheng S, Yang J, Feng J, Zhang W, Li Z, Chen Q, Xia Y, Ouyang Z, Ma X. Large-scale lipid analysis with C=C location and sn-position isomer resolving power. Nat Commun 2020; 11:375. [PMID: 31953382 PMCID: PMC6969141 DOI: 10.1038/s41467-019-14180-4] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/16/2019] [Indexed: 12/18/2022] Open
Abstract
Lipids play a pivotal role in biological processes and lipid analysis by mass spectrometry (MS) has significantly advanced lipidomic studies. While the structure specificity of lipid analysis proves to be critical for studying the biological functions of lipids, current mainstream methods for large-scale lipid analysis can only identify the lipid classes and fatty acyl chains, leaving the C=C location and sn-position unidentified. In this study, combining photochemistry and tandem MS we develop a simple but effective workflow to enable large-scale and near-complete lipid structure characterization with a powerful capability of identifying C=C location(s) and sn-position(s) simultaneously. Quantitation of lipid structure isomers at multiple levels of specificity is achieved and different subtypes of human breast cancer cells are successfully discriminated. Remarkably, human lung cancer tissues can only be distinguished from adjacent normal tissues using quantitative results of both lipid C=C location and sn-position isomers.
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Affiliation(s)
- Wenbo Cao
- Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, 100084, China
| | - Simin Cheng
- Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, 100084, China
| | - Jing Yang
- Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, 100084, China
| | - Jiaxin Feng
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Wenpeng Zhang
- Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, 100084, China
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Zishuai Li
- Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, 100084, China
| | - Qinhua Chen
- Affiliated Dongfeng Hospital, Hubei University of Medicine, Shiyan, Hubei Province, 442000, China
| | - Yu Xia
- Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zheng Ouyang
- Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, 100084, China.
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA.
| | - Xiaoxiao Ma
- Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, 100084, China.
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31
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Macias LA, Feider CL, Eberlin LS, Brodbelt JS. Hybrid 193 nm Ultraviolet Photodissociation Mass Spectrometry Localizes Cardiolipin Unsaturations. Anal Chem 2019; 91:12509-12516. [PMID: 31490676 DOI: 10.1021/acs.analchem.9b03278] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Developing alternative MS/MS strategies to distinguish isomeric lipids has become a high impact goal in shotgun lipidomics. Novel approaches have been developed to resolve structural features that are not discernible by traditional shotgun methods and have consequently promoted the discovery of new disease biomarkers. However, these methods have largely been limited to characterizing lipids with low structural complexity. Here, ultraviolet photodissociation (UVPD) strategies for phospholipid characterization are expanded for analysis of cardiolipins (CL), a class of phospholipids that exhibits a higher degree of structural complexity. A hybrid collision induced dissociation/193 nm UVPD (CID/UVPD) approach was implemented to pinpoint the location of both double bond and cyclopropyl unsaturations on the four acyl chains of CLs. This strategy was complemented with CID for the de novo elucidation of unknown CLs in biological extracts.
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Affiliation(s)
- Luis A Macias
- Department of Chemistry , University of Texas , Austin , Texas 78712 , United States
| | - Clara L Feider
- Department of Chemistry , University of Texas , Austin , Texas 78712 , United States
| | - Livia S Eberlin
- Department of Chemistry , University of Texas , Austin , Texas 78712 , United States
| | - Jennifer S Brodbelt
- Department of Chemistry , University of Texas , Austin , Texas 78712 , United States
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Wäldchen F, Spengler B, Heiles S. Reactive Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging Using an Intrinsically Photoreactive Paternò-Büchi Matrix for Double-Bond Localization in Isomeric Phospholipids. J Am Chem Soc 2019; 141:11816-11820. [PMID: 31318556 DOI: 10.1021/jacs.9b05868] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The location and identity of phospholipids (PLs) within tissues can serve as diagnostic markers for tissue types or diseases. Whereas mass spectrometry imaging (MSI) has emerged as a powerful bioanalytical tool to visualize PL distributions, inferring PL identities from MSI experiments is challenging. Especially, C═C double-bond (DB) positions are not identifiable in most MSI experiments. Herein, we introduce benzophenone (BPh) as a novel reactive matrix for matrix-assisted laser desorption/ionization (MALDI). BPh promotes desorption/ionization and simultaneously serves as derivatization reagent that allows functionalization of unsaturated PLs during the MALDI process via a laser-light driven Paternò-Büchi (PB) reaction without the need for additional equipment. Using BPh, PB product ions of numerous PL classes are readily generated to pinpoint the location of DBs. High lateral resolution MSI results of DB-position isomers are presented, highlighting the capabilities of BPh as a PB-reactive MALDI matrix to potentially unveil the impact of DB-position isomers in PL metabolism.
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Affiliation(s)
- Fabian Wäldchen
- Institute of Inorganic and Analytical Chemistry, Analytical Chemistry , Justus Liebig University Giessen , Heinrich Buff Ring 17 , 35392 Giessen , Germany
| | - Bernhard Spengler
- Institute of Inorganic and Analytical Chemistry, Analytical Chemistry , Justus Liebig University Giessen , Heinrich Buff Ring 17 , 35392 Giessen , Germany
| | - Sven Heiles
- Institute of Inorganic and Analytical Chemistry, Analytical Chemistry , Justus Liebig University Giessen , Heinrich Buff Ring 17 , 35392 Giessen , Germany
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