Kinetics and thermodynamics of the association of dehydroergosterol with lipid bilayer membranes.
Biophys J
; 93(12): 4244-53, 2007 Dec 15.
Article
en En
| MEDLINE
| ID: mdl-17766353
ABSTRACT
We have examined the detailed kinetics and thermodynamics of the association of Ergosta-5,7,9(11),22-tetraen-3beta-ol (dehydroergosterol, DHE) with lipid bilayers prepared from 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), a 11 binary mixture of POPC and cholesterol (Chol), and a 64 binary mixture of egg sphingomyelin (SpM) and Chol. Association of DHE with all three membranes was shown to be entropically driven, most so in the case of SpM-Chol bilayers. Equilibrium partition coefficients for partitioning of DHE between the lipid phase and the aqueous phase were shown to be similar for POPC and POPC-Chol bilayers between 15 and 35 degrees C. Partitioning into the SpM-Chol bilayer is favored at higher temperatures and there is a crossover in solubility preference at approximately 25 degrees C. Insertion (k(+)) and desorption (k(-)) rate constants were shown to be very similar for POPC and POPC-Chol bilayer membranes, but were lower for SpM-Chol bilayers. Similar results were previously reported by us for the association of other amphiphiles with these membranes. We propose a model for the microscopic structure of a POPC-Chol (11) bilayer membrane that is consistent with these observations.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Fosfolípidos
/
Ergosterol
/
Membrana Dobles de Lípidos
/
Fluidez de la Membrana
Tipo de estudio:
Risk_factors_studies
Idioma:
En
Año:
2007
Tipo del documento:
Article