Structure of the dimyristoylphosphatidylcholine vesicle and the complex formed by its interaction with apolipoprotein C-III: x-ray small angle scattering studies

Publisher Website
Google Scholar
Abstract
Single bilayer vesicles of dimyristoylphosphatidylcholine were investigated by small-angle X-ray scattering at 28.degree. C. The results indicate that these vesicles are hollow spherical shell structures with an outer radius of approximately 12 nm and a MW of (3.2 .+-. 0.5) .times. 106. The shell was 4.4 .+-. 0.2 nm thick with a cross-sectional electron-density profile characteristic for a single phospholipid bilayer. Upon interaction of these vesicles with apolipoprotein C-III from human very low density lipoproteins at a protein/lipid ratio greater than 0.08 (g/g), a complex containing 0.25 g of protein/g of lipid, with MW of (3.9 .+-. 0.4) .times. 105, is formed. The shape analysis indicates a highly asymmetric particle with an internal partition of low and high electron density resembling that produced by a bilayer structure. Model calculations and curve-fitting procedures show good agreement between the experimental scattering curve and that computed for an oblate ellipsoidal structure with dimensions of 17 .times. 17 .times. 5 nm and a 1 nm thick shell of high electron density surrounding the core of low electron density.