| Autor: |
Andres T. Cavazos, Horia I. Petrache, Morris I. Bank, Justin A. Williams, Paul E. Harper, Bruce D. Ray, Jeffrey Atkinson, Stephen R. Wassall, Jacob J. Kinnun |
| Jazyk: |
angličtina |
| Předmět: |
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| Zdroj: |
Biophysical Journal. (2):412a |
| ISSN: |
0006-3495 |
| DOI: |
10.1016/j.bpj.2014.11.2260 |
| Popis: |
Vitamin E (α-tocopherol) is a lipid-soluble antioxidant that has the role of protecting phospholipids from oxidation in membranes. A question that remains is how the low concentration of α-tocopherol found in whole cells can protect the relatively large concentration of polyunsaturated phospholipids found in membranes that are particularly vulnerable to oxidative attack. We hypothesize that α-tocopherol co-localizes with polyunsaturated phospholipids to optimize its role as an antioxidant. This project attempts to test this hypothesis by comparing the effect of α-tocopherol on the molecular organization of 1-palmitoyl-2-docosahexaenoyl-sn-glycerophosphatidylethanolamine (16:0-22:6PE, PDPE) and, as a monounsaturated control, 1-palmitoyl-2-oleoyl-sn-glycerophosphatidylethanolamine (16:0-18:1PE, POPE) in mixtures with sphingomyelin (SM). By solid-state 2H NMR spectroscopy, we directly observe order and phase behavior of POPE-d31 and PDPE-d31 (analogs of POPE and PDPE with a perdeuterated sn-1 chain) in the mixed membranes. In complementary X-ray diffraction and differential scanning calorimetry experiments we further probe phase behavior. The spectra observed for POPE-d31 in POPE/SM/α-tocopherol (2:2:1 mol) reveal that a transition from gel to liquid crystalline phase is no longer apparent. At higher temperatures there is a superposition of two spectral components that we ascribe to α-tocopherol promoting a transition from lamellar to inverted hexagonal (HII) phase. Analysis of depaked spectra shows that order is increased by about 8 % and that the amount of HII phase increases with temperature, ranging from 7 (31°C) to 41 % (65°C). In mixed membranes where POPE-d31 is replaced by PDPE-d31, we shall investigate whether there is a greater tendency for α-tocopherol to increase order and destabilize bilayer structure for the polyunsaturated phospholipid. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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