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A model membrane approach to the epidermal permeability barrier: an X-ray diffraction study
J A Bouwstra1, J Thewalt, G S Gooris
1Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, Leiden University, The Netherlands.
Biochemistry
|June 24, 1997
Summary
Mammalian skin barrier function relies on lamellar lipid structures. Ceramides, even with cholesterol, form crystalline phases crucial for skin permeability, unlike sphingomyelin which forms fluid phases.
Area of Science:
- Biophysics
- Dermatology
- Materials Science
Background:
- Mammalian skin permeability is primarily regulated by lipid lamellar structures in the stratum corneum.
- These lamellae differ from typical biological membranes due to a unique lipid composition: ceramides, cholesterol, and free fatty acids.
Purpose of the Study:
- To investigate the phase behavior of ceramide-cholesterol lipid dispersions.
- To compare the structural properties of ceramide-based lamellae with sphingomyelin-based lamellae.
Main Methods:
- Deuterium Nuclear Magnetic Resonance (NMR) spectroscopy was used to study lipid dispersions.
- X-ray diffraction was employed to analyze the structural phases of the dispersions at pH 5.2.
Main Results:
- Ceramide and cholesterol dispersions exhibited complex crystalline phases between room temperature and approximately 40°C.
- The majority of crystalline cholesterol was integrated within the ceramide phase, not separate.
- Analogous dispersions with sphingomyelin showed a fluid lamellar phase under identical conditions.
Conclusions:
- Ceramides, even with significant cholesterol, can form crystalline lamellar structures.
- These ceramide-cholesterol crystalline structures may play a vital role in the epidermal permeability barrier.
- Interactions between ceramides and cholesterol in other biological membranes could lead to unique physical properties.