Anisotropic interactions in hydrated cerebrosides. A theoretical model of stable and metastable states and hydrogen-bond formation
✍ Scribed by David A. Pink; A.Leo MacDonald; Bonnie Quinn
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 945 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0009-3084
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✦ Synopsis
We describe a model of the hydrocarbon-chain gel-to-fluid phase transition in hydrated N-palmitoylgalactosyl sphingnsine (NPGS) bilayer membranes. The model includes both isotropic and anisotropic interactions. The isotropic interaction yields a phase transition near 41 °C as in the case of dipalmitoyi phosphatidylcholine (DPPC), and we investigate whether the thermodynamic behaviour of NPGS can be understood as a consequence of a stronger isotropic interaction or whether, instead, an anisotropic interaction, due possibly to hydrogen-bond formation between lipids, is also necessary. We f'md that the experimental data cannot be explained only by isotropic interactions. We find that the model with the additional anlsotropic interaction accounts for both equilibrium and non-equilibirum experimental data. We predict various phenomena in quenching from a high to a low temperature, followed by a subsequent increase in temperature and we relate these to changes in the infrared spectra of the amide I and II bands.