Abstract
The complex permittivities of l-α-lysolecithin in the absence and presence of the gramicidin A ion channel were measured over the temperature range 0-60°C and over the frequency range 1-1000 MHz. One dielectric relaxation/loss has been observed. It is located at 103.3 MHz (1.54 ns) for a micellar 0.4 M l-α-lysolecithin solution at 20°C, whereas it is shifted to 71.7 MHz (2.22 ns) for a lamellar l-α-lysolecithin-gramicidin A aqueous solution (0.4 M l-α-lysolecithin, 0.0308 M gramicidin A) at 20°C. The dielectric relaxation decreases and the relaxation time increases when gramicidin A is incorporated into l-α-lysolecithin. These dielectric changes are related, in part, to the micellar-to-lamellar lipid phase transition induced by the incorporation of gramicidin A into lysolecithin. We suggest that the diffuse rotational motion of the polar head group Of l-α-lysolecithin contributes to the dielectric relaxation/loss at around 100 MHz.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 199-209 |
| Number of pages | 11 |
| Journal | Biophysical Chemistry |
| Volume | 32 |
| Issue number | 2-3 |
| DOIs | |
| State | Published - Dec 1988 |
Funding
This work was supported by NIH grant GM26898. RB. was supported in part by the Swiss National Science Foundation and C.H.L. held a National Education Commission of the People’s Republic of China Scholarship. Our thanks are due to Professor D.W. Urry for helpful discussions and for the use of the dielectric instrumentation in his laboratory, to Dr. A. Killian for discussions,t o D. Hains for taking the CD spectra and to D. Harris for his technical help.
Keywords
- Dielectric permittivity Polypeptide-lipid interaction
- Dielectric spectroscopy
- Gramicidin A
- l-α-Lysophosphatidylcholine
ASJC Scopus subject areas
- Biophysics
- Biochemistry
- Organic Chemistry