Systematic analysis of choline-containing phospholipids using multi-dimensional mass spectrometry-based shotgun lipidomics

Abstract

Herein, a systematic study on the identification and quantitation of choline-containing phospholipid molecular species, including choline glycerophospholipid (PC), lysoPC, and sphingomyelin (SM), is described using multi-dimensional mass spectrometry-based shotgun lipidomics after intrasource separation (MDMS-SL). Current methods for analysis of choline-containing lipids were improved through multiple modifications leading to: (1) identification of constituents present in the PC and SM classes, subclasses of PC, and individual molecular species using MDMS-SL analysis in the positive-ion mode; (2) identification of the fatty acyl constituents and their regiospecificity in diacyl PC molecular species through the neutral loss of trimethylamine plus fatty acids; (3) direct identification of the alkenyl chains of plasmenylcholine species using precursor ion scans of the fragment ions carrying the alkenyl chains; (4) elimination of the effects of polyunsaturation on the quantitation of PC species by multiple ratiometric comparisons; (5) accurate identification and quantitation of lysoPC molecular species including regioisomers by diagnostic fragment ions; and (6) accurate identification and quantitation of SM molecular species by neutral loss scans of phosphocholine plus methyl aldehyde which is specific to SM molecular species. With these enhancements, the application of MDMS-SL for the analyses of choline-containing phospholipid molecular species in biomedical research has been extended to a much larger number of molecular species with greater quantitative accuracy and an increased depth of structural information.

Tales and Mysteries of the Enigmatic Sphingomyelin Synthase Family

“…[49][50][51][52][53] Recent evidence has further enriched this model supporting a role for SM in the homeostasis of lipid microdomains at the plasma membrane, often sites of receptor-mediated signaling. Taking advantage of the identification of SMS1 as bona fide SM synthase, the role of SM in the activation of Fas signaling was investigated by Miyaji et al 75 Comparing SMS1 deficient cells (with over expressed Fas receptor) with cells in which expression of SMS1 was restored, the authors provide evidence for a critical role of SM in Fas-mediated signaling by enabling the formation of the death-inducing signaling complex (DISC) and consequently allowing caspase activation and production of ceramide at the plasma membrane.…”

“…Alternatively, dihydrosphingosine (sphinganine) or 4-hydroxysphinganine (phytosphingosine) could account for the sphingoid backbone and unsaturated and/or branched fatty acids could also be found. 49,50 Even though structurally similar, SM and phosphatidylcholine (PC) differ significantly for a number of features that determine the higher melting temperature of the first. In fact, the predominant presence of saturated fatty acids and the potential intermolecular hydrogen binding, via the amide bond and the free hydroxyl group at position 3, favor a high-density packing of SM, which increases the compactness and impermeability of the membrane.…”

ER phospholipid composition modulates lipogenesis during feeding and in obesity

“…Individual molecular species were quantified by comparing the ion intensities of the individual molecular species to that of the lipid class internal standard with additional corrections for type I and type II 13C isotope effects (36 Major PC species identified in ER membrane were subjected to further analyses to provide information for the regioisomers of acyl chains. The sodiated adducts of major species were subjected to CAD analyses, which yield regioisomer information by determining the ratio of the fragment ions from the loss of trimethylamine and the fatty acid of the parent molecular ion (37). This technique has been shown to provide over 2-to 4-fold greater ion intensity for the loss of the fatty acyl chain from the sn-1 position.…”

Dynamic simulation of cardiolipin remodeling: greasing the wheels for an interpretative approach to lipidomics

“…Lipid molecular species were identifi ed, quantifi ed, and acyl chain designation determined using a MDMS-SL approach as previously described ( 1,5,30,31 ). Product-ion analyses of cardiolipin molecular species by using a high mass accuracy/high resolution mass spectrometer [i.e., Orbitrap-LTQ mass spectrometer (Thermo Scientifi c San Jose, CA)] were also preformed as previously described ( 32 ) to verify the presence of very low abundance cardiolipin isomers.…”