1
|
Brydon SC, Poad BLJ, Fang M, Rustam YH, Young RSE, Mouradov D, Sieber OM, Mitchell TW, Reid GE, Blanksby SJ, Marshall DL. Cross-Validation of Lipid Structure Assignment Using Orthogonal Ion Activation Modalities on the Same Mass Spectrometer. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1976-1990. [PMID: 39037040 DOI: 10.1021/jasms.4c00221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
The onset and progression of cancer is associated with changes in the composition of the lipidome. Therefore, better understanding of the molecular mechanisms of these disease states requires detailed structural characterization of the individual lipids within the complex cellular milieu. Recently, changes in the unsaturation profile of membrane lipids have been observed in cancer cells and tissues, but assigning the position(s) of carbon-carbon double bonds in fatty acyl chains carried by membrane phospholipids, including the resolution of lipid regioisomers, has proven analytically challenging. Conventional tandem mass spectrometry approaches based on collision-induced dissociation of ionized glycerophospholipids do not yield spectra that are indicative of the location(s) of carbon-carbon double bonds. Ozone-induced dissociation (OzID) and ultraviolet photodissociation (UVPD) have emerged as alternative ion activation modalities wherein diagnostic product ions can enable de novo assignment of position(s) of unsaturation based on predictable fragmentation behaviors. Here, for the first time, OzID and UVPD (193 nm) mass spectra are acquired on the same mass spectrometer to evaluate the relative performance of the two modalities for lipid identification and to interrogate the respective fragmentation pathways under comparable conditions. Based on investigations of lipid standards, fragmentation rules for each technique are expanded to increase confidence in structural assignments and exclude potential false positives. Parallel application of both methods to unsaturated phosphatidylcholines extracted from isogenic colorectal cancer cell lines provides high confidence in the assignment of multiple double bond isomers in these samples and cross-validates relative changes in isomer abundance.
Collapse
Affiliation(s)
- Samuel C Brydon
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia
| | - Berwyck L J Poad
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia
- Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD 4001, Australia
| | - Mengxuan Fang
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Yepy H Rustam
- Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Reuben S E Young
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Dmitri Mouradov
- Personalized Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Oliver M Sieber
- Personalized Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Todd W Mitchell
- Molecular Horizons and School of Medical, Indigenous and Health Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Gavin E Reid
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
- Department of Biochemistry and Pharmacology, University of Melbourne, Parkville, VIC 3010, Australia
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia
| | - Stephen J Blanksby
- School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD 4001, Australia
- Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD 4001, Australia
| | - David L Marshall
- Central Analytical Research Facility, Queensland University of Technology, Brisbane, QLD 4001, Australia
| |
Collapse
|
2
|
Nixon CA. The Composition and Chemistry of Titan's Atmosphere. ACS EARTH & SPACE CHEMISTRY 2024; 8:406-456. [PMID: 38533193 PMCID: PMC10961852 DOI: 10.1021/acsearthspacechem.2c00041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 11/02/2023] [Accepted: 02/02/2024] [Indexed: 03/28/2024]
Abstract
In this review I summarize the current state of knowledge about the composition of Titan's atmosphere and our current understanding of the suggested chemistry that leads to that observed composition. I begin with our present knowledge of the atmospheric composition, garnered from a variety of measurements including Cassini-Huygens, the Atacama Large Millimeter/submillimeter Array, and other ground- and space-based telescopes. This review focuses on the typical vertical profiles of gases at low latitudes rather than global and temporal variations. The main body of the review presents a chemical description of how complex molecules are believed to arise from simpler species, considering all known "stable" molecules-those that have been uniquely identified in the neutral atmosphere. The last section of the review is devoted to the gaps in our present knowledge of Titan's chemical composition and how further work may fill those gaps.
Collapse
Affiliation(s)
- Conor A. Nixon
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771, United
States
| |
Collapse
|
7
|
Fuß W, Lochbrunner S, Müller A, Schikarski T, Schmid W, Trushin S. Pathway approach to ultrafast photochemistry: potential surfaces, conical intersections and isomerizations of small polyenes. Chem Phys 1998. [DOI: 10.1016/s0301-0104(98)00114-1] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
9
|
Van Bramer SE, Ross PL, Johnston MV. Unimolecular photochemistry of n-alkenes studied by photodissociation-photoionization mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1993; 4:65-72. [PMID: 24234746 DOI: 10.1016/1044-0305(93)85044-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/1992] [Revised: 08/03/1992] [Accepted: 08/11/1992] [Indexed: 06/02/2023]
Abstract
The 193-nm unimolecular photochemistry of n-alkenes from C5 to C14 is studied by photodissociation-photoionization mass spectrometry (PDPI/MS). In PDPI/MS, a UV laser induces neutral unimolecular photodissociation. The resulting neutral fragments and any remaining parent molecules are then softly ionized with coherent vacuum UV radiation and mass analyzed. Photodissociation of n-alkenes is dominated by cleavage of the β C-C bond. Products of α- and γ-cleavage are typically less than 20% as abundant as the β-cleavage fragments. Secondary fragmentation of the primary products occurs both by neutral fragmentation during photodissociation and by ionic fragmentation during photoionization. The energetics of the neutral secondary reactions indicate that between 400 and 500 kJ/mol is consumed during photodissociation. The abundances of many secondary fragmentation products decrease with increasing molecular size. Because neutral fragmentation occurs without significant isomerization, PDPI/MS provides structural information that is not available from ionic fragmentation in conventional mass spectrometric experiments.
Collapse
Affiliation(s)
- S E Van Bramer
- Department of Chemistry and Biochemistry, University of Delaware, 19716, Newark, DE
| | | | | |
Collapse
|
10
|
Cromwell EF, Stolow A, Vrakking MJJ, Lee YT. Dynamics of ethylene photodissociation from rovibrational and translational energy distributions of H2products. J Chem Phys 1992. [DOI: 10.1063/1.462942] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|