European Biophysics Journal

, Volume 24, Issue 6, pp 423–431

Thermotropism and hydration properties of POPE and POPE-cholesterol systems as revealed by solid state2H and31P-NMR

  • Radoslav Marinov
  • Erick J. Dufourc
Article

DOI: 10.1007/BF00576714

Cite this article as:
Marinov, R. & Dufourc, E.J. Eur Biophys J (1996) 24: 423. doi:10.1007/BF00576714

Abstract

The partial phase diagram and the hydration properties of the 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE)-water system, in the absence and presence of 30 mol% cholesterol, have been investigated by solid state phosphorus NMR of the lipid and deuterium NMR of heavy water. The POPE-D2O phase diagram resembles other phosphatidylethanolamine (PE)-water systems: below water-to-lipid molar ratios (Ri) of 3 the lamellar gel (Lβ or Lc)-to-hexagonal type II (HII) phase sequence is observed on increasing the temperature. For Ri≥3 the thermotropic sequence (Lβ or Lc)-Lα-HII is detected. On increasing hydration from Ri=3, the HII phase is detected from 40°C to 85°C whereas the gel phase is observed from 40°C to 30°C. The limiting hydrations of the gel, Lα and HII phases are Ri ≈ 3, 17 and 20, respectively. The number of bound water molecules per lipid is ca. 8 in both the La and HII phases. The presence of cholesterol stabilizes the hexagonal phase 20°C below temperatures at which it is observed in its absence and reduces the limiting hydration of the fluid and hexagonal phases to Ri ≈ 9 and 14, respectively. The structure and/or dynamics of the water bound to the interface are markedly modified on going from the Lα to the HII phase.

Key words

Phosphatidylethanolamine Cholesterol Phase diagram Hydration 2H and 31P NMR 

Abbreviations

NMR

Nuclear magnetic resonance

DDPE

1,2-Didodecyl-rac-glycerol-3-phosphoethanol-amine

DHPE

1,2-Dihexadecyl-sn-glycerol-3-phosphoethanol-amine

DOPE

1,2-Dioleoyl-sn-glycerol-3-phosphoethanol-amine

POPE

1-Palmitoyl-2-oleoyl-sn-glycerol-3-phosphoetha-nolamine

DAPE

1,2-Diarachinoyl-sn-glycerol-3-phosphoethanol-amine

DMPC

1,2-Dimyristol-sn-glycerol-3-phosphocholine

DPPC

1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine

Tc

lamellar gel-to-lamellar fluid transition temperature

Th

lamellar fluid-to-hexagonal transition temperature

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Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • Radoslav Marinov
    • 1
  • Erick J. Dufourc
    • 2
  1. 1.Institute of Solid State Physics, Bulgarian Academy of SciencesSofiaBulgaria
  2. 2.Centre de Recherche Paul Pascal, CNRSPessacFrance

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