Browsing by Author "Stillwell, William H."

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    DHA and EPA Interaction with Raft Domains Observed With Solid-State 2H NMR Spectroscopy
    (Office of the Vice Chancellor for Research, 2013-04-05) Kinnun, Jacob J.; Williams, Justin A.; Stillwell, William H.; Bittman, Robert; Shaikh, Saame Raza; Wassall, Stephen R.
    Research continues to examine the health benefits of omega-3 polyunsaturated fatty acids (n-3 PUFA) found in fish oils. The major bioactive components are eicosapentaenoic acid (EPA, 20:5), with 20 carbons and 5 double bonds, and docosahexaenoic acid (DHA, 22:6), with 22 carbons and 6 double bonds. However, their molecular modes of action remain unclear. A suggested hypothesis is that these fatty acids are incorporated into membrane phospholipids and modify the structure and organization of lipid rafts, thus affecting cell signaling. We used solid-state 2H NMR spectroscopy to compare molecular organization in mixtures of 1-palmitoyl-2-eicosapentaenoylphosphatidylcholine (PEPC) and 1-palmitoyl-2-docosahexaenoylphosphatidylcholine (PDPC) with the raft-stabilizing molecules sphingomyelin (SM) and cholesterol. Our spectra for PEPC-d31 and PDPC-d31, analogs of PEPC and PDPC with a perdeuterated palmitoyl sn-1 chain, showed that DHA has a greater tendency than EPA to incorporate into raft-like domains enriched in SM and cholesterol. By using PSM-d31, an analog of SM with a perdeuterated N-palmitoyl chain, we now directly observe one of the raft-forming molecules and analyze the molecular order within the raft. These results will add to the growing information on how EPA and DHA differentially modify lipid domain organization in bilayers.