Analytical Considerations of Stable Isotope Labelling in Lipidomics

Abstract

Over the last two decades, lipids have come to be understood as far more than merely components of cellular membranes and forms of energy storage, and are now also being implicated to play important roles in a variety of diseases, with lipid biomarker research one of the most widespread applications of lipidomic techniques both in research and in clinical settings. Stable isotope labelling has become a staple technique in the analysis of small molecule metabolism and dynamics, as it is the only experimental setup by which biosynthesis, remodelling and degradation of biomolecules can be directly measured. Using state-of-the-art analytical technologies such as chromatography-coupled high resolution tandem mass spectrometry, the stable isotope label can be precisely localized and quantified within the biomolecules. The application of stable isotope labelling to lipidomics is however complicated by the diversity of lipids and the complexity of the necessary data analysis. This article discusses key experimental aspects of stable isotope labelling in the field of mass spectrometry-based lipidomics, summarizes current applications and provides an outlook on future developments and potential.

Instant on-paper protein digestion during blood spot sampling

“…13 C or 15 N) (preferably by two or more labeling sites to avoid confusion with naturally occurring isotopes), but could also be by deuterium 71 . For protein determinations, isotope labeling may be the preferred method since heavy labeling with 2 H could face hydrogen exchange during storage resulting in degradation of the IS and thus, give inaccurate results 72 . Furthermore, retention shifts during LC separation is also a potential drawback of 2 H IS.…”

Recurrent Topics in Mass Spectrometry-Based Metabolomics and Lipidomics—Standardization, Coverage, and Throughput

“…The important application of supplied stable isotope tracers in metabolomics for flux and tracer studies is comprehensively covered elsewhere. 38 − 41 Labeled biomass was used early on in quantitative omics workflows, e.g. amino acid labeling to monitor proteome changes upon system perturbation.…”

NMR Methods for Determining Lipid Turnover via Stable Isotope Resolved Metabolomics

“…We use both multinuclear NMR and UHR-MS (UltraHigh Resolution Mass Spectrometry) to analyze multi-elemental isotopologues [29,30]. Although stable isotope tracing has been widely used for polar metabolites, it has not been extensively applied to lipidomics, which is almost exclusively studied by mass spectrometry [13,20,[31][32][33]. Furthermore, with some exceptions, much of the MS-based lipid tracing has used deuterium, such as the incorporation from heavy water in physiological experiments [19,33].…”

“…Furthermore, with some exceptions, much of the MS-based lipid tracing has used deuterium, such as the incorporation from heavy water in physiological experiments [19,33]. Although NMR is generally much less sensitive than MS, and the resolution of lipid species is low in NMR, there are global features of lipid mixtures than are more readily accessible by NMR than by MS, especially in the context of 13 C metabolic tracing [20,34,35]. There has been increasing interest in using NMR with stable isotope tracing for lipid analysis, in a diverse range of settings [36][37][38][39][40].…”

“…There has been increasing interest in using NMR with stable isotope tracing for lipid analysis, in a diverse range of settings [36][37][38][39][40]. The use of a 2 H or 13 C stable isotope tracer or a combination of both for NMR analysis to study de novo lipogenesis has been reported [40,41]. However, direct 2 H or 13 C detection have low sensitivity, so it is very time-consuming to acquire high-quality spectra compared with 1 H detection.…”