Influence of Cholesterol Esters of Varying Unsaturation
نویسندگان
چکیده
Previous work has shown that cholesterol esters are relatively insoluble (<5 mol%) in bilayer phosphatidylcholine and sphingomyelin systems, but exhibit greater solubility in hexagonal (HII) phase anhydrous phosphatidylcholine systems obtained above 100°C. We examine here the influence of cholesterol esters of varying unsaturation on fully hydrated egg phosphatidylethanolamine systems, which undergo a bilayer to hexagonal (Hll) phase transition as the temperature is increased through TBH = 28°C. We show that all esters investigated (cholesteryl stearate, myristate, oleate, linoleate and linolenate) progressively decrease TBH as the mole fraction of ester is increased to at least equimolar proportions. The more unsaturated species have larger effects. These results indicate that cholesterol esters are miscible in phosphatidylethanolamine dispersions and suggest a 'cone' shape of intercalated cholesterol ester. Further, the major influence of cholesterol esters on phospholipid phase structure appears to be determined by the nature of the esterified fatty acid.
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