Comprehensive Quantification of Triacylglycerols in Soybean Seeds by Electrospray Ionization Mass Spectrometry with Multiple Neutral Loss Scans

Abstract

Soybean seeds are an important source of vegetable oil and biomaterials. The content of individual triacylglycerol species (TAG) in soybean seeds is difficult to quantify in an accurate and rapid way. The present study establishes an approach to quantify TAG species in soybean seeds utilizing an electrospray ionization tandem mass spectrometry with multiple neutral loss scans. Ten neutral loss scans were performed to detect the fatty acyl chains of TAG, including palmitic (P, 16:0), linolenic (Ln, 18:3), linoleic (L, 18:2), oleic (O, 18:1), stearic (S, 18:0), eicosadienoic (20:2), gadoleic (20:1), arachidic (20:0), erucic (22:1), and behenic (22:0). The abundance of ten fatty acyl chains at 46 TAG masses (mass-to-charge ratio, m/z) were determined after isotopic deconvolution and correction by adjustment factors at each TAG mass. The direct sample infusion and multiple internal standards correction allowed a rapid and accurate quantification of TAG species. Ninety-three TAG species were resolved and their levels were determined. The most abundant TAG species were LLL, OLL, LLLn, PLL, OLLn, OOL, POL, and SLL. Many new species were detected and quantified. This shotgun lipidomics approach should facilitate the study of TAG metabolism and genetic breeding of soybean seeds for desirable TAG content and composition.

Structure Annotation and Quantification of Wheat Seed Oxidized Lipids by High-Resolution LC-MS/MS

“…This might result partially from the above-mentioned coisolation of several lipids with different FA composition in an MS/MS scan, but it is not likely to be the major cause for this observation. As reported by others, lipids with identical sum formulae may occur as multiple isomers in one chromatographic peak (Xu et al, 2009;Li et al, 2014). Lipid isomerism is caused by differences in FA length and distribution along the glycerol backbone, distribution of double bonds and their cis/trans-conformations, and, in the case of oxidized lipids, additional asymmetric centers per oxidation.…”

Shotgun Lipidomics Approach to Stabilize the Regiospecificity of Monoglycerides Using a Facile Low-Temperature Derivatization Enabling Their Definitive Identification and Quantitation

“…Since triacylglycerols have been successfully analyzed with either alkali metal (e.g., Na + or Li + ) 37–41 or ammonium adducts, 42–48 we next examined acylated MGs using long-chain fatty acids. As expected, the MS/MS spectra of ammonium adducts of d 4 -palmitic acid ( d 4 -PA)-derivatized 1- and 2-LG both demonstrated two diagnostic fragment ions at m / z 579 and m / z 559 resulting from loss of NH 3 + d 4 -PA and NH 3 + linoleic acid, respectively (Figure 1A).…”

Comprehensive lipid profiling of early stage oocytes and embryos by MRM profiling

“…20,21 It is known that free fatty acids are present in both follicular fluid and in the cumulus oocyte complex's intracellular stores. 18 The enclosed oocyte is rapidly able to incorporate FAs from its microenvironment as has been demonstrated in vitro for unsaturated oleic and linoleic acids. 20,21 Thus, free fatty acids composition may be used to produce energy through the beta-oxidation pathway to boost maturation progression and improve developmental competence in bovine.…”

“…Triacylglycerol (TAG) lipids were profiled based on the NL of esterified palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), arachidic (C20:0), and arachidonic (C20:4) fatty acyl residues. 18 Lipids containing odd number of carbons were excluded since they are not abundant in oocytes and embryos. This strategy allowed compaction of the large number of entries (14,184) When only gametes (IO and OM) were included in the analysis, the PCA revealed distinct lipid distributions between the groups and a number of PC, SM, as well as some cholesteryl ester ions with differential abundance between the IO and OM groups at 1.5 fold change or higher ( Figure S1 and Tables 2 and S2).…”