| Autor: |
Dekker CJ, Geurts van Kessel WS, Klomp JP, Pieters J, De Kruijff B |
| Jazyk: |
angličtina |
| Zdroj: |
Chemistry and physics of lipids [Chem Phys Lipids] 1983 Jul; Vol. 33 (1), pp. 93-106. |
| DOI: |
10.1016/0009-3084(83)90012-9 |
| Abstrakt: |
A series of phosphatidylcholines and phosphatidylethanolamines was synthesized containing two acyl chains of the following polyunsaturated fatty acids: linoleic acid (18:2), linolenic acid (18:3), arachidonic acid (20:4) and docosahexaenoic acid (22:6). In addition two phospholipids with mixed acid composition were synthesized: 16:0/18:1c phosphatidylcholine and 16:0/18:1c phosphatidylethanolamine. The structural properties of these lipids in aqueous dispersions in the absence and in the presence of equimolar cholesterol were studied using 31P-NMR, freeze fracturing and differential scanning calorimetry (DSC). The phosphatidylcholines adopt a bilayer configuration above 0 degrees C. Incorporation of 50 mol% of cholesterol in polyunsaturated species induces a transition at elevated temperatures into structures with 31P-NMR characteristics typical of non-bilayer organizations. When the acyl chains contain three or more double bonds, this non-bilayer organization is most likely the hexagonal HII phase. 16:0/18:1c phosphatidylethanolamine shows a bilayer to hexagonal transition temperature of 75 degrees C. The polyunsaturated phosphatidylethanolamines exhibit a bilayer to hexagonal transition temperature below 0 degrees C which decreases with increasing unsaturation and which is lowered by approximately 10 degrees C upon incorporation of 50 mol% of cholesterol. Finally, it was found that small amounts of polyunsaturated fatty acyl chains in a phosphatidylethanolamine disproportionally lower its bilayer to hexagonal transition temperature. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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