Different oxidized phospholipid molecules unequally affect bilayer packing

Abstract

The aim of this study was to gain more detailed knowledge about the effect of the presence of defined oxidized phospholipid molecules in phospholipid bilayers. After chromatographic and mass spectrometry analysis, the previously used product of the Fenton reaction with unsaturated lecithins proved to consist of a plethora of oxidatively modified lecithins, useless either for the detailed study of the effects brought about in the bilayer or as the source of defined oxidized phospholipid molecules. The latter, particularly 2-(omega-carboxyacyl)- and 2-(n-hydroperoxyacyl)-lecithins, can be more conveniently prepared by chemical or enzymatic synthesis rather than by chemical or physical oxidation. The effect of those molecules and of commercially available 12-hydroxy-stearic and dodecanedioic acid was studied in planar supported phospholipid bilayers (SPBs) by use of EPR spectrometry. The SPBs also contained 2-(5-doxylstearoyl)-lecithin as the spin probe, and the EPR spectral anisotropy loss, indicative of bilayer disordering, was measured as a function of the molar percentage of oxidized lipid. Most oxidized lipid molecules examined in this study were able to induce bilayer disordering, while hydroperoxyl group-bearing acyl chains appeared to be much less effective. It is concluded that the effects of different oxidized phospholipids on phospholipid bilayer structure cannot be generalized, as happens with batch-oxidized phospholipids, and that the use of defined oxidized phospholipid molecular species for membrane oxidative stress guarantees a more reliable and detailed response.

Suppression of Mitochondrial Function by Oxidatively Truncated Phospholipids Is Reversible, Aided by Bid, and Suppressed by Bcl-XL

“…The sn-2 glutaroyl fragment, like the azelaoyl fragment derived from oxidative cleavage of the more abundant linoleoyl residues, contains an ionizable carboxyl function at the end of the shortened sn-2 fatty acyl fragment. The glutaroyl fragment is shorter than the azelaoyl fragment by 4 methylene molecules, and the decreased hydrophobicity of the glutaroyl residue had a less severe effect on bilayer organization than the longer azelaoyl fragment (39). Still, glutaroyl phosphatidylcholine will induce apoptotic cell death (40) and, like Az-LPAF, is internalized (12,41).…”

Effects of hyperbaric gases on membrane nanostructure and function in neurons

“…One possible scenario is that HBO 2 -induced membrane blebbing occurs via altered membrane phospholipid organization (55,71) and changes in plasma membrane fluidity (11,65,93). In addition, HBO 2 could promote membrane blebbing via the oxidation of cytoskeletal proteins (57) and membranecytoskeleton bonds such as adhesion molecules (78).…”

Does hydrogen bonding contribute to lipoperoxidation-dependent membrane fluidity variation? An EPR-spin labeling study

“…The bilayer structure of SPB, even in case of heavy oxidation, is guaranteed by the membrane forming ability of diHpLPC previously demonstrated by gel-chromatography and DLS, so that the loss of EPR spectral anisotropy in SPB can be attributed to misaligning of fatty acid chains rather than to scrambling of the bilayer structure, as previously stated [4,8,[15][16][17], also in keeping with other studies [25][26][27]. The rise of EPR anisotropy loss in SPB containing increasing molar ratios of diHpLPC is visible in Fig.…”

“…After 10-min stirring at room temperature lipoxygenase was added (4000 U/ml) and stirring was continued for 4 h under a gentle air bubbling into the medium. Lipids were extracted from the reaction mixture by the method of Bligh and Dyer [7], and the pure oxidized species was separated from the residual starting lecithin by flash chromatography using CH 3 OH/(C 2 H 5 ) 2 O/H 2 O 95:5:2 (vol) as the eluting solvent [8]. Typical recovery of the oxidized form was 5-6 μmol, as determined by the phosphorus assay according to Nakamura [9].…”

“…Phospholipid spin labeling 1-Palmitoyl-2-(n-doxylstearoyl)-sn-glycero-3-phosphocholines (n-DSPPC) were prepared by acylation of 1-palmitoyl-2-lyso-sn-glycero-3-phosphorylcholine with the corresponding n-doxylstearic acid by the method of Boss et al [12]. Pure n-DSPC was obtained by flash chromatography [8] of lipids extracted [7] from the final reaction mixture.…”