title: A rapid ambient ionization-mass spectrometry approach to monitoring the relative abundance of isomeric glycerophospholipids.
abstract: Glycerophospholipids with two, non-equivalent fatty acyl chains can adopt one of two isomeric forms depending on the relative position of substitutions on the glycerol backbone. These so-called sn-positional isomers can have distinct biophysical and biochemical behaviors making it desirable to uniquely assign their regiochemistries. Unambiguous assignment of such similar molecular structures in complex biological extracts is a significant challenge to current analytical technologies. We have recently reported a novel mass spectrometric method that combines collision- and ozone-induced dissociation in series (CID/OzID) to yield product ions characteristic of acyl chain substitution patterns in glycerophospholipids. Here phosphatidylcholines are examined using the CID/OzID protocol combined with desorption electrospray ionization (DESI) to facilitate the rapid exploration of sample arrays comprised of a wide variety of synthetic and biological sources. Comparison of the spectra acquired from different extracts reveals that the sn-positional isomers PC 16:0/18:1 and PC 18:1/16:0 (where the 18:1 chain is present at the sn-2 and sn-1 position of the glycerol backbone, respectively) are most often found together in lipids of either natural or synthetic origin. Moreover, the proportions of the two isomers vary significantly between extracts from different organisms or even between adjacent tissues from the same organism.
authors.affiliation: 1] School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia [2] Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Kozlowski
authors.affiliation: 1] Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia [2] School of Health Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia.
authors.forename: Todd W
authors.initials: TW
authors.lastname: Mitchell
authors.affiliation: 1] School of Chemistry, University of Wollongong, Wollongong, NSW, 2522, Australia [2] Central Analytical Research Facility, Queensland University of Technology, Brisbane QLD, 4001, Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Blanksby
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D020404:Glycerophospholipids / Q000032:analysis* / Q000737:chemistry / Q000592:standards; D007477:Ions / Q000737:chemistry; D007536:Isomerism; D007679:Kidney Medulla / Q000737:chemistry / Q000378:metabolism; D007908:Lens, Crystalline / Q000737:chemistry / Q000378:metabolism; D010063:Ovum / Q000737:chemistry / Q000378:metabolism; D010126:Ozone / Q000737:chemistry; D012015:Reference Standards; D021241:Spectrometry, Mass, Electrospray Ionization / Q000592:standards
chemical_list: D020404:Glycerophospholipids; D007477:Ions; D010126:Ozone