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 is studied. 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 multi bilayer vesicles. A higher yield and more homogeneous density distribution of lipid apoprotein complexes results from the interaction of apoC III with the single bilayer vesicles relative to those obtained with the multi bilayer 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 multi shelled 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||BBA - Biochimica et Biophysica Acta|
|State||Published - Jan 18 1976|
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