glycerophosphoserine and glycerophosphoethanolamine

The evidence that oxidized phospholipids play a role in signaling, apoptotic events and in age-related diseases is responsible for the increasing interest for the study of this subject. Phospholipid changes induced by oxidative reactions yield a huge number of structurally different oxidation products which difficult their isolation and characterization. Mass spectrometry (MS), and tandem mass spectrometry (MS/MS) using the soft ionization methods (electrospray and matrix-assisted laser desorption ionization) is one of the finest approaches for the study of oxidized phospholipids. Product ions in tandem mass spectra of oxidized phospholipids, allow identifying changes in the fatty acyl chain and specific features such as presence of new functional groups in the molecule and their location along the fatty acyl chain. This review describes the work published on the use of mass spectrometry in identifying oxidized phospholipids from the different classes.

Topics: Cardiolipins; Fatty Acids; Mass Spectrometry; Oxidation-Reduction; Phosphatidylethanolamines; Phospholipids; Phosphorylcholine; Phosphoserine; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Sphingomyelins; Tandem Mass Spectrometry

Topics: Animals; Choline; Cricetinae; Decarboxylation; Glycerophospholipids; Humans; Isotopes; Mass Spectrometry; Methylation; Phosphatidylethanolamines; Phosphoserine; Rats; Saccharomyces cerevisiae; Signal Transduction; Substrate Specificity

Receptor activation leads to the dynamic remodeling of the plasma membrane. Previous work using immunoelectron microscopy showed that aggregated high-affinity receptor for immunoglobulin E (FcRI) and aggregated Thy-1, a glycerophosphoinositol (GPI)-anchored protein, have distinct membrane distributions. We now report lipidomics analysis of FcRI- and Thy-1-enriched vesicles obtained by magnetic bead isolation in the absence of detergent. Protein analyses show that FcRI domains are enriched in receptors and associated signaling molecules, whereas Thy-1 domains are devoid of FcRI subunits. Positive and negative ion electrospray mass spectrometry demonstrated that both domains retained a complex mixture of phospholipid classes and molecular species, predominantly glycerophosphocholine, glycerophosphoethanolamine (GPE), and sphingomyelin as well as glycerophosphoserine and GPI lipids. Analysis of total acyl groups showed that < 50% of fatty acids in these domains are fully saturated, inconsistent with the recruitment of aggregated receptors or GPI-anchored proteins to liquid ordered domains. However, further analysis showed that FcRI domains contain two times more sphingomyelin and a high ratio of cholesterol to total fatty acid content compared with Thy 1-enriched domains. Remarkably, plasmenyl glycerophosphoethanolamine phospholipids (plasmalogen GPE) were also 2.5-3 times more abundant in FcRI domains than in the Thy-1 microdomains, whereas most diacyl GPE molecular species were equally abundant in the two domains.

Topics: Animals; Cell Line, Tumor; Cell Membrane; Chromatography, High Pressure Liquid; Comet Assay; Glycerylphosphorylcholine; Glycosylphosphatidylinositols; Immunomagnetic Separation; Membrane Lipids; Membrane Microdomains; Membrane Proteins; Phosphatidylethanolamines; Phosphoserine; Receptors, IgE; Spectrometry, Mass, Electrospray Ionization; Sphingomyelins; Thy-1 Antigens

The effects of metal cationization on collisionally activated dissociation (CAD) of phospholipids were investigated by electrospray ionization with quadrupole ion trap tandem mass spectrometry. The metal ions include Li(+), Na(+), K(+), Sr(2+), Ba(2+), and the first transition series. CAD of the transition metal ion-bound lipid complexes gave significant yields of product ions that identify the positions of the two fatty acyl substituents on the glycerophospholipid backbone. The cobalt(II) ion, which has a single naturally occurring isotope, was expected to be a better cationization reagent as it produces simpler mass spectra than other transition metal ions. CAD of the cobalt(II) ion complexes of glycerophosphoethanolamines, glycerophosphoglycerols and glycerophosphoserines yielded product ions that revealed information regarding both the lipid classes and the regiospecific positions of the two fatty acyl substituents.

Topics: Glycerophosphates; Ions; Metals; Molecular Structure; Phosphatidylethanolamines; Phospholipids; Phosphoserine; Spectrometry, Mass, Electrospray Ionization

Structural evidence is presented for a 'Ca(2+)-bridging' mechanism, proposed for Ca(2+)-binding interfacial membrane proteins such as annexins, protein kinase C, and certain coagulation proteins. Crystal structures of Ca(2+)-annexin V complexes with phospholipid polar heads provide molecular details of 'Ca(2+)-bridges' as key features in the membrane attachment exhibited by these proteins. Distinct binding sites for phospholipid head groups are observed, including a novel, double-Ca2+ recognition site for phosphoserine that may serve as a phosphatidylserine receptor site in vivo.

Topics: Amino Acid Sequence; Annexin A5; Annexins; Calcium; Membranes; Models, Molecular; Molecular Sequence Data; Phosphatidylethanolamines; Phospholipids; Phosphoserine; Protein Binding

The individual molecular species composition of diacyl, alkylacyl and alkenylacyl glycerophospholipids was determined in mouse peritoneal macrophages. A marked heterogeneity in the relative composition (mol%) of macrophage ether and ester phospholipid individual species was noted. High concentrations of 16:0-20:4 were found in ether phospholipids such as alkenylacyl glycerophosphoethanolamine (GPE; 27.5 mol%) and alkylacyl glycerophosphocholine (GPC; 16.6%) as compared to mol% levels of 16:0-20:4 in diacyl GPE (5.7%) and diacyl GPC (8.1%), respectively. Interestingly, alkenylacyl GPE was highly enriched in 1-ether (16:0) relative to alkylacyl GPC. The predominant diacyl molecular species in glycerophosphoinositol (GPI) and glycerophosphoserine (GPS) were 18:0-20:4 (59.1%) and 16:0-18:1 (41.1%), respectively. It is noteworthy that the level of 18:0-20:4 was several times higher in diacyl GPI (59.1%) than in diacyl GPS (11.1%), diacyl GPE (25.7%), and diacyl GPC (3.7%). The most abundant molecular species in diacyl GPC and diacyl GPE were 16:0-18:1 (29.9%) and 18:0-20:4 (25.7%), respectively. The abundance of 20:4 in ether phospholipids, specifically 16:0-20:4 and 18:0-20:4, in alkylacyl GPC is significant in view of the role these antecedents play in the biosynthesis of platelet-activating factor (PAF) and 20:4-derived eicosanoids in stimulated macrophages. The unique molecular species composition of the peritoneal macrophage distinguishes this cell type from others.

Topics: Animals; Chromatography, High Pressure Liquid; Glycerylphosphorylcholine; Inositol Phosphates; Macrophages; Male; Mice; Mice, Inbred C57BL; Peritoneal Cavity; Phosphatidylethanolamines; Phospholipid Ethers; Phospholipids; Phosphoserine