We have studied the interaction of an apolipoprotein from human very low density lipoproteins (apoC-III) with egg yolk phosphatidylcholine in the form of single- and multi-bilayer vesicles. The reactivity of single-bilayer vesicles with apoC-III1 appears to be greater than that of the multi-bilayer vesicles according to several thermodynamic and spectroscopic criteria. In the complexes formed by the association of apoC-III with single-bilayer vesicles, the α-helical content of the peptide backbone and the apolarity of the environment around the tryptophan residues are greater than that observed in the complexes formed with the multibilayer vesicles. A higher yield and more homogeneous density distribution of lipid-apoprotein complexes results from the interaction of apoC-with the single-bilayer vesicles relative to those obtained with the multibilayer vesicles. The enthalpy of association of apoC-III1 with phospholipid was greater for the single-shelled vesicles (25 kcal/mol apoC-III1) than for the multishelled ones (18 kcal/mol apoC-III1). The difference in reactivity of these two types of liposomes is not due to a difference in their fluidities since their fatty acid compositions are identical, but may be due to a difference in their areas of sterically accessible phospholipid, their permeabilities to the apoprotein, their radii of curvation, or a combination of these factors.
|Original language||English (US)|
|Number of pages||11|
|Journal||Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism|
|State||Published - Jan 18 1977|
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