Structural studies on archaeal phytanyl-ether lipids isolated from membranes of extreme halophiles by linear ion-trap multiple-stage tandem mass spectrometry with electrospray ionization

Abstract

The structures of archaeal glycerophospholipids and glycolipids are unique in that they consist of phytanyl substituents ether linked to the glycerol backbone, imparting stability to the molecules. In this contribution, we described multiple-stage linear ion-trap combined with high resolution mass spectrometry toward structural characterization of this lipid family desorbed as lithiated adduct ions or as the [M –H]− and [M – 2H]2− ions by ESI. MSn on various forms of the lithiated adduct ions yielded rich structurally informative ions leading to complete structure identification of this lipid family, including the location of the methyl branches of the phytanyl chain. By contrast, structural information deriving from MSn on the [M –H]− and [M – 2H]2− ions is not complete. The fragmentation pathways in an ion-trap, including unusual internal loss of glycerol moiety and internal loss of hexose found for this lipid family were proposed. This mass spectrometric approach provides a simple tool to facilitate confident characterization of this unique lipid family.

Glycerol monoalkanediol diethers: a novel series of archaeal lipids detected in hydrothermal environments

“…The MS/MS spectrum of component I was characterized by major product ions at m/z 1226.2 (–18; H 2 O) as well as m/z 1170.1 (–74; C 3 H 6 O 2 ). Similar neutral losses have previously been observed in the MS/MS spectra of isoprenoid GDGTs and GDDs as well as archaeal phytanyl‐ether lipids, where they have been attributed to the fragmentation of the terminal or internal glycerol moieties, respectively. In contrast to isoprenoid GDDs, however, in which the most favored neutral loss in MS/MS is derived from a single molecule of water and a saturated biphytane resulting in a base peak ion at m/z 669.8, component I does not contain any product ions in the low molecular mass range as commonly observed for isoprenoid GDGTs and GDDs (Fig.…”

Structural characterization of ether lipids from the archaeonSulfolobus islandicusby high-resolution shotgun lipidomics

“…These cumbersome approaches have been used to elucidate the stereochemistry of glycerol moieties in core structures as well as to determine the position of methyl groups and cyclopentane moieties in isoprenoid chains . The structural characterization of intact archaeal lipids has been performed using both shotgun lipidomics and chromatography‐mass spectrometry‐based approaches . These approaches typically require a relatively small amount of sample and a short time of analysis but provide data with limited structural information, which, to varying extends, only allows inferring putative head group structures, the total number of carbon atoms and cyclopentane moieties or double bonds in the core structure and occasionally the position of structural features provided that high‐quality synthetic standards are available as a reference.…”

Phytansäure

“…Solche Membranlipide findet man bei den echten Bakterien (Eubakterien) und Eukaryoten überhaupt nicht. Diese Membranlipide haben zwei für das Überleben in Extremsituationen besonders wichtige Eigenschaften: Durch die Phytyl‐Ketten sind sie einerseits resistent gegenüber der peroxidativen Wirkung des Sauerstoffs und die Etherbindung verhält sich andererseits stabil gegenüber einer Hydrolyse .…”