IMPEDANCE ANALYSIS OF LIPID DOMAINS
IN PHOSPHATIDYLCHOLINE BILAYER MEMBRANES
CONTAINING ERGOSTEROL
Monika Naumowicz 1 and Zbigniew Artur Figaszewski 2*
1 Institute of Chemistry, University of Bialystok, Al. J. Pilsudskiego 11/4, 15-443 Bialystok, Poland
2 Institute of Chemistry, University of Bialystok, Al. J. Pilsudskiego 11/4, 15-443 Bialystok, Poland,
* To whom correspondence should be addressed. E-mail: elchem{at}uwb.edu.pl.
Submitted on March 23, 2005
Revised on May 17, 2005
Accepted on 7 July 2005
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Abstract |
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The effect of ergosterol on the electrochemical features of the phosphatidylcholine bilayer membrane was investigated by impedance spectroscopy. The experimental impedance values obtained in the presence of different amounts of ergosterol showed evidence of domain structures within the bilayer containing less than 0.06 molar fraction of ergosterol. Based on derived mathematical equations, the surface area of phospholipid/ergosterol domain was calculated; it amounts to 262 Å2. This value is consistent, taking into consideration the presented measurements as well as ordering and condensation effects of ergosterol, with a stoichiometry of such a domain equal to 3:1. The result of the investigation is the proposal of a new and simple method for the determination of the surface area and description stoichiometry of domains formed in any two-component system.
Key Words:
bilayer lipid membrane, impedance spectroscopy, surface area phosphatidylcholine/ergosterol domain
