Thermodynamics of lipid membrane solubilization by sodium dodecyl sulfate.
Biophys J
; 90(12): 4509-21, 2006 Jun 15.
Article
en En
| MEDLINE
| ID: mdl-16581838
ABSTRACT
We provide a comprehensive thermodynamic description of lipid membrane dissolution by a charged detergent. To this end, we have studied the interactions between the anionic detergent sodium dodecyl sulfate (SDS) and the zwitterionic phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) in dilute aqueous solution (10 mM phosphate buffer, 154 mM NaCl, pH 7.4). Thermodynamic parameters of vesicle solubilization and reconstitution, membrane partitioning, and micelle formation were assessed by right-angle light scattering and isothermal titration calorimetry. Membrane translocation and dissolution proceed very slowly at 25 degrees C but are considerably accelerated at 65 degrees C. At this temperature, a simple SDS/POPC phase diagram (comprising vesicular, coexistence, and micellar ranges) and a complete set of partition coefficients and transfer enthalpies were obtained. Electrostatic repulsion effects at the membrane surface were implemented by combining Gouy-Chapman theory with a Langmuir adsorption isotherm to account for Na+ binding to membrane-incorporated DS-. This approach offered a quantitative understanding of solubilization and reconstitution processes, which were interpreted in terms of partition equilibria between and ideal mixing in all phases. More than any other property, the transbilayer flip-flop rate under given experimental conditions hence appears to dictate a detergent's suitability for thermodynamically controlled lipid membrane solubilization and reconstitution.
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1
Base de datos:
MEDLINE
Asunto principal:
Fosfatidilcolinas
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Dodecil Sulfato de Sodio
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Membrana Dobles de Lípidos
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Liposomas
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Fluidez de la Membrana
Idioma:
En
Revista:
Biophys J
Año:
2006
Tipo del documento:
Article