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Biophysical Journal Sep 2020The segregation of lipids into lateral membrane domains has been extensively studied. It is well established that the structural differences between phospholipids play...
The segregation of lipids into lateral membrane domains has been extensively studied. It is well established that the structural differences between phospholipids play an important role in lateral membrane organization. When a high enough cholesterol concentration is present in the bilayer, liquid-ordered (L) domains, which are enriched in cholesterol and saturated phospholipids such as sphingomyelin (SM), may form. We have recently shown that such a formation of domains can be facilitated by the affinity differences of cholesterol for the saturated and unsaturated phospholipids present in the bilayer. In mammalian membranes, the saturated phospholipids are usually SMs with different acyl chains, the abundance of which vary with cell type. In this study, we investigated how the acyl chain structure of SMs affects the formation of SM- and cholesterol-enriched domains. From the analysis of trans-parinaric acid fluorescence emission lifetimes, we could determine that cholesterol facilitated lateral segregation most with the SMs that had 16 carbon-long acyl chains. Using differential scanning calorimetry and Förster resonance energy transfer techniques, we observed that the SM- and cholesterol-enriched domains with 16 carbon-long SMs were most thermally stabilized by cholesterol. The Förster resonance energy transfer technique also suggested that the same SMs also form the largest L domains. In agreement with our previously published data, the extent of influence that cholesterol had on the propensity of lateral segregation and the properties of L domains correlated with the relative affinity of cholesterol for the phospholipids present in the bilayers. Therefore, the specific SM species present in the membranes, together with unsaturated phospholipids and cholesterol, can be used by the cell to fine-tune the lateral structure of the membranes.
Topics: Calorimetry, Differential Scanning; Cholesterol; Lipid Bilayers; Phospholipids; Sphingomyelins
PubMed: 32755561
DOI: 10.1016/j.bpj.2020.07.014 -
Journal of Oleo Science Sep 2020In this study, seed oils of Thladiantha nudiflora and Thladiantha dubia were found to contain 55.5 and 44.4% mole of conjugated octadecatrienoic fatty acids,...
In this study, seed oils of Thladiantha nudiflora and Thladiantha dubia were found to contain 55.5 and 44.4% mole of conjugated octadecatrienoic fatty acids, respectively. The presence of moieties of conjugated fatty acids was confirmed by a series from physical methods: UV, IR, H and C NMR. The triacylglycerols (TAGs) isolated of the seed oils were studied by RP-HPLC with diode array and mass spectrometric detections. It was shown that all 15 TAGs of Thladiantha dubia contain moieties of conjugated fatty acids - punicic, (9Z,11E,13Z)-octadeca-9,11,13-trienoic acid (35.6% mole) and 8.9% mole α-eleostearic, (9Z,11E,13E)-octadeca-9,11,13-trienoic acid. Meanwhile, 24 TAGs of Thladiantha nudiflora seed oil contain both acids in approximately equal proportions (27.4:28.2 % mole). The enrichment for polyunsaturated fatty acids of the hydrolysis product of the seed oils due to urea inclusion complex formation was discussed.
Topics: Chromatography, High Pressure Liquid; Cucurbitaceae; Fatty Acids, Unsaturated; Magnetic Resonance Spectroscopy; Mass Spectrometry; Plant Oils; Seeds; Triglycerides
PubMed: 32788518
DOI: 10.5650/jos.ess20075