Electrospray mass spectrometry of phospholipids

Abstract

Phospholipids play a central role in the biochemistry of all living cells. These molecules constitute the lipid bilayer defining the outer confines of a cell, but also serve as the structural entities which confine subcellular components. Mass spectrometry has emerged as a powerful tool useful for the qualitative and quantitative analysis of complex phospholipids, including glycerophospholipids and the sphingolipid, sphingomyelin. Collision induced decomposition of both positive and negative molecular ion species yield rich information as to the polar head group of the phospholipid and the fatty-acyl substituents esterified to the glycerophospholipid backbone. This review presents the current level of understanding of the mechanisms involved in the formation of various product ions following collisional activation of molecular ion species generated by electrospray ionization of the common glycerophospholipids, including phosphatidic acid, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, phosphatidylserine, cardiolipin, and sphingomyelin. Recent advances in the application of matrix assisted laser desorption ionization is also considered. Several applications of mass spectrometry applied to phospholipid analysis are presented as they apply to physiology as well as pathophysiology.

Electrospray ionization tandem mass spectrometry of glycerophosphoethanolamine plasmalogen phospholipids

“…One way to achieve detailed structural analysis of glycerophospholipids is by using electrospray tandem mass spectrometry [8]. Glycerophospholipids consist of a glycerol backbone with a fatty acyl or 1-O-alkyl group at the sn-1 position, an acyl group at the sn-2 position, and a phosphate ester group with a polar head group at the sn-3 position.…”

“…Glycerophospholipids consist of a glycerol backbone with a fatty acyl or 1-O-alkyl group at the sn-1 position, an acyl group at the sn-2 position, and a phosphate ester group with a polar head group at the sn-3 position. Collision-induced dissociation of the [M ϩ H] ϩ or [M Ϫ H] Ϫ of glycerophospholipids results in fragment ions that are related to the polar head group and the fatty acyl substituents esterified to the glycerol backbone [8]. One of the principal fragmentation pathways during collision-induced dissociation (CID) in the positive ion mode is cleavage of the phosphate-glycerol bond, which results in the elimination of the polar head group as a neutral or charged species.…”

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of cardiolipin extracted from detergent-solubilized mitochondrial electron transfer complexes

“…A number of studies have demonstrated the use of mass spectrometry for characterization of phospholipids and particularly cardiolipin (for review, see [13]). Most recently, for example, Hsu and Turk [14] described a multiple-stage ion-trap mass spectrometric approach with electrospray ionization for structural characterization of cardiolipin.…”

A review of chromatographic methods for the assessment of phospholipids in biological samples

“…However, there are many disadvantages to using TLC for phospholipid analysis. First, the technique may destroy the phospholipid structure (Pulfer and Murphy, 2003) owing to either oxidation or hydrolysis of the phospholipids while exposed to the atmosphere on the plate (Guan et al, 2001). Second, TLC has relatively poor reproducibility compared with HPLC or GC (Breton et al, 1989).…”

“…Most cell membranes are composed of phosphatidyl linkages (Han and Gross, 2004). The bond for the sn-2 fatty acid is always an ester bond (Pulfer and Murphy, 2003) and unsaturated fatty acids are preferred. Common notation for a molecular species follows the format x:y with x representing the number of carbons and y the number of double bonds.…”