A three component model for the lipid barrier of the stratum corneum (SC) consisting of ceramide III, cholesterol, and perdeuterated palmitic acid, has been characterized by Fourier transform infrared spectroscopy. At physiological temperature the CD2 scissoring mode of the palmitic acid methylenes, and the CH2 rocking mode of the ceramide methylenes, are each split into two components. This indicates that both components exist in separate, conformationally ordered phases, probably with orthorhombic perpendicular subcells. The magnitude of the splitting indicates that the domains are at least 100 chains in size. The thermotropic behavior of the CD2 stretching vibrations demonstrates that conformational disordering of the palmitic acid commences at 42°C with a transition midpoint of 50°C. The CH2 stretching frequency indicates the ceramide chains remain ordered until 50°C then disorder with a midpoint of 67°C. The results provide a molecular characterization for the complex low temperature (10-40°C) dynamic behavior suggested by recent 2H NMR experiments.
|Number of pages
|Biochemical and Biophysical Research Communications
|Published - Feb 24 1997
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology