sn‐Position determination of phospholipid‐linked fatty acids derived from erythrocytes by liquid chromatography electrospray ionization ion‐trap mass spectrometry

Abstract

The sn-position of FA in membrane lipids has an influence on the physiological function of cells, is predictive for diseases, and therefore is useful for diagnostics. The current study compares the compositions of acyl chain substituents in the sn-1 and sn-2 positions of the glycerol backbones of phospholipids derived from human erythrocytes by using RP-HPLC coupled with on-line electrospray ionization ion trap MS. Preferential loss of the acyl group in the sn-1 position was used to determine the degree of regiospecific preference exhibited by the phospholipid molecules. The identities of the molecular species and the positions of the acyl substituents were identified using product-ion spectra of major precursor ions selected from the mass spectra averaged across peaks in the total ion chromatogram. Saturated FA were found to be located mainly in the sn-1 position of the glycerol backbones of erythrocyte phospholipids, whereas PUFA were found primarily in the sn-2 position. All measured phospholipids revealed palmitic acid (16:0) at the sn-1 position. Linoleic acid (18:2n-6) and arachidonic acid (20:4n-6) were found to be attached exclusively to the sn-2 position of the backbone, whereas eicosadienoic (20:2n-6) and eicosatrienoic acid (20:3n-9) occurred in both positions of the backbone of PC. Oleic (18:1n-9), linoleic (18:2n-6), and octadecatrienoic (18:3) acids of PE and PS were linked to both positions. Lignoceric acid (24:1 n-9) was found to be strictly localized at the sn-2 position, whereas nervonic (24:1n-9) acid of PS was associated with both positions of the backbone. A detailed analysis of the blood cell membrane lipids by MS might be helpful to characterize postprandial kinetics of pharmacological or dietary lipid applications, as well as environmental influences on cell membranes.

Identification of prostamides, fatty acyl ethanolamines, and their biosynthetic precursors in rabbit cornea

“…7 ). This could be attributed to the higher prevalence of their respective fatty acids at position sn -1 of the phosphatidylcholine (PC) precursor ( 39 ). DH-EA and AL-EA were minor congeners (0.4 and 0.7 pg/mg tissue, respectively), indicating very low levels of DHA and ␣ -linolenic incorporation at the sn -1 position of corneal PC available for transacylation to the amine terminal of phosphatidylethanolamine (PE) ( 40 ).…”

Breast milk fatty acid profile in relation to infant growth and body composition: results from the INFAT study

“…The analysis of FAs was performed at the Laboratory of Lipid Research, Danone Research, Centre for Specialised Nutrition, Friedrichsdorf, Germany, according to established protocols (34,35). FA values are presented as percentage of FA/total FA.…”

Molecular Species of the Alcohol Biomarker Phosphatidylethanol in Human Blood Measured by LC-MS

“…1. In phospholipids isolated from human erythrocytes, saturated fatty acids (e.g., 16:0, palmitic acid) are mainly located in the sn-1 position and unsaturated fatty acids (e.g., 18:2, linoleic acid) mainly in the sn-2 position (26,31 ). The corresponding deprotonated molecules used in SIM of different PEth species and PProp are listed in Table 1.…”