Density fluctuations and rotational isomerization in phospholipid bilayers as studied by ultrasonic absorption spectroscopy
✍ Scribed by Udo Kaatze; Martin Brai
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 345 KB
- Volume
- 65
- Category
- Article
- ISSN
- 0009-3084
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✦ Synopsis
Broadband ultrasonic absorption spectra are discussed for some aqueous solutions of single-walled phospholipid bilayer vesicles. It is shown that the excess absorption found with all samples can be represented by a sum of a Debye-type relaxation term with discrete relaxation time and a Fixman-Kawasaki term. The former term reflects the kinetics of structural isomerization of the hydrocarbon chains. The values of its relaxation time (0.09-0.56 ns) agree with those for pure n-alkanes of comparable length. The latter terms seems to be due to density fluctuations in the hydrocarbon part of the double layer. Fluctuation correlation lengths between 1 and 30 A result from the analysis of the ultrasonic spectra.