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Sterols stabilize the ripple phase structure in dihexadecylphosphatidylcholine
B A Cunningham1, L Midmore, O Kucuk
1Department of Physics, Bucknell University, Lewisburg, PA 17837.
Biochimica Et Biophysica Acta
|January 26, 1995
Summary
Sterols alter dihexadecylphosphatidylcholine (DHPC) lipid bilayers, preventing alkyl chain interdigitation and favoring ripple phases. This study reveals sterols stabilize ripple phases in DHPC mixtures.
Area of Science:
- Lipid Bilayer Structure
- Sterol-Lipid Interactions
- Phase Transitions
Background:
- Dihexadecylphosphatidylcholine (DHPC) forms complex lipid bilayers.
- Sterols are known to modulate membrane properties.
- Understanding sterol effects on DHPC is crucial for membrane biophysics.
Purpose of the Study:
- To investigate the structural effects of various sterols on DHPC bilayers.
- To characterize the phase behavior of DHPC-sterol mixtures.
- To elucidate the role of sterols in stabilizing specific lipid phases.
Main Methods:
- Static X-ray diffraction of temperature-equilibrated DHPC-sterol samples.
- Real-time X-ray diffraction during temperature scans.
- Analysis of lipid bilayer phase transitions and structural changes.
Main Results:
- Sterols prevent alkyl chain interdigitation in DHPC sub-gel and gel states.
- Sterols stabilize the ripple gel-state at the expense of the gel-state bilayer.
- DHPC-sterol mixtures exhibit ripple-ripple phase transitions.
- 5 alpha-cholestane-3 beta,5,6 beta-triol induces ripple mesophase even with disordered DHPC chains.
Conclusions:
- Sterols significantly alter DHPC bilayer structure and phase behavior.
- Sterols promote the formation and stability of ripple phases in DHPC mixtures.
- Specific sterols can maintain ripple mesophase structures under conditions that normally disrupt them.