| Autor: |
Pagano, R., Ruysschaert, J., Miller, I., Pagano, R E, Ruysschaert, J M, Miller, I R |
| Zdroj: |
Journal of Membrane Biology; 1972, Vol. 10 Issue 1, p11-30, 20p |
| Abstrakt: |
An analytical technique is described for direct determination of the molecular composition of lipid bilayer membranes in aqueous solution. Membranes formed from chemically pure, radioactively labeled components, were sampled by pipetting a mercury droplet through the bilayer-water interface. During this procedure, the membrane remains intact but decreases in area with a concomitant increase in the area of the surrounding bulk phase. It is shown that each mercury droplet is covered with a fragment of the bilayer membrane in the form of a closed vesicle. The chemical composition of the bilayer is determined from an analysis of the readioactivity on the mercury droplet. Bilayers generated from glyceryl monooleate in n-decane or n-hexadecane contain (4.7±0.4)×10 molecules of monoglyceride per cm and a minimum of (2.8±0.7)×10 molecules of solvent ( n-hexadecane) per cm. It is estimated from these numbers that 37 vol % of the hydrocarbon core of the bilayer is occupied by solvent. The composition relationships between the bilayer and bulk membrane-forming solution were determined for mixtures of glyceryl monooleate (GMO) with cholesterol (Chol) or glyceryl monostearate (GMS). It was found that [GMS/GMO]≃[GMS/GMO], and [Chol/GMO]=0.5[Chol/GMO]. While the molecular areas of glyceryl monooleate and glyceryl monostearate are unchanged in the mixed system, the average area for mixtures of cholesterol and glyceryl monooleate is decreased, suggesting a condensing effect of the sterol in the bilayer analogous to that observed in lipid monolayers. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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