NMR Methods for Determining Lipid Turnover via Stable Isotope Resolved Metabolomics.

Penghui Lin,Leonard M Neckers,Teresa W-M Fan,Daniel R Crooks,Richard M Higashi,Li Dai,Andrew N Lane

doi:10.3390/metabo11040202

Penghui Lin, Leonard M Neckers + Show 5 more

Open Access

https://doi.org/10.3390/metabo11040202

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Abstract

Lipids comprise diverse classes of compounds that are important for the structure and properties of membranes, as high-energy fuel sources and as signaling molecules. Therefore, the turnover rates of these varied classes of lipids are fundamental to cellular function. However, their enormous chemical diversity and dynamic range in cells makes detailed analysis very complex. Furthermore, although stable isotope tracers enable the determination of synthesis and degradation of complex lipids, the numbers of distinguishable molecules increase enormously, which exacerbates the problem. Although LC-MS-MS (Liquid Chromatography-Tandem Mass Spectrometry) is the standard for lipidomics, NMR can add value in global lipid analysis and isotopomer distributions of intact lipids. Here, we describe new developments in NMR analysis for assessing global lipid content and isotopic enrichment of mixtures of complex lipids for two cell lines (PC3 and UMUC3) using both 13C6 glucose and 13C5 glutamine tracers.

Highlights

Lipids comprise an extremely diverse group of compounds that have a wide range of biological functions from structure to signaling molecules
That approach is less suited for addressing questions about lipids in bulk including the major metabolic subunit labeling and the relative abundances of classes of complex lipids
Instead of quantifying individual lipid species, we investigated the overall substructure of the lipid functional groups and traced the incorporation of 13C from [U-13C]-glucose or [U-13C]-glutamine

Summary

Introduction

Lipids comprise an extremely diverse group of compounds that have a wide range of biological functions from structure (e.g., membranes) to signaling molecules. Even discounting all the many ways in which they form complexes with other molecules, lipids come in an enormous diversity of forms [1,2]. These range from fatty acids as short as acetate (n = 2) to palmitic acid, the end product of fatty acid synthase activity (n = 16), to longer chain fatty acids such as arachidonic acids (n = 24), which are incorporated into complex lipids via esterification to a variety of headgroups (Figure S1, Scheme S1). Most of this work has been done by mass spectrometry, there are increasingly extensive databases being made available for heteronuclear NMR [9,10], which complements the LC MS/MS methods commonly used

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