ROLE OF THE POSITION OF UNSATURATION ON THE PHASE-BEHAVIOR AND INTRINSIC CURVATURE OF PHOSPHATIDYLETHANOLAMINES

Citation
Rm. Epand et al., ROLE OF THE POSITION OF UNSATURATION ON THE PHASE-BEHAVIOR AND INTRINSIC CURVATURE OF PHOSPHATIDYLETHANOLAMINES, Biophysical journal, 71(4), 1996, pp. 1806-1810
Citations number
23
Categorie Soggetti
Biophysics
Journal title
ISSN journal
00063495
Volume
71
Issue
4
Year of publication
1996
Pages
1806 - 1810
Database
ISI
SICI code
0006-3495(1996)71:4<1806:ROTPOU>2.0.ZU;2-O
Abstract
The bilayer-to-hexagonal phase transition temperatures (T-H) of di-18: 1(c) phosphatidylethanolamine with double bonds at positions 6, 9, and 11 are 37 degrees C, 8 degrees C, and 28 degrees C, respectively, as measured by differential scanning calorimetry and x-ray diffraction. T hus T-H exhibits a minimum when the C=C is around position 9, similar to what has been found for the gel-to-liquid crystalline phase transit ion temperature in other lipids. Factors that may contribute to the de pendence of T-H on double bond position were studied by x-ray diffract ion of the hexagonal phases in the presence and absence of added alkan e: with or without the osmotic stress of polyethylene glycol, and over a wide temperature range, The lattice dimensions show that the intrin sic radius of lipid monolayer curvature increases as the double bond i s moved toward the tail ends. A measure of the bending moduli of these lipid monolayers shows a higher value for the 9 position, and lower v alues for the other two, Consideration of the bilayer-to-hexagonal tra nsition in terms of bending and interstitial energies provides a ratio nale for the relative values of T-H.