IX International Conference on Small Angle Scattering

J. Phys. IV France 03 (1993) C8-257-C8-260
DOI: 10.1051/jp4:1993850

Structural investigations of native and oxidised LDL using X-ray and neutron solution scattering techniques

D.F. MEYER, A.S. NEALIS, K.R. BRUCKDORFER and S.J. PERKINS

Department of Biochemistry and Chemistry, Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF, UK.

Abstract
The gross structures of both the native and oxidised (atherogenic) forms of low density lipoproteins (LDL) were compared using neutron and X-ray solution scattering. Neutron data in ²H₂O solutions showed that native LDL is well represented as a quasispherical structure, while X-ray data showed that the internal structure of LDL has lipid in the core and apo-B100 protein and phospholipid headgroups on the surface. When LDL oxidation was induced using a ratio of 6.4 µM Cu²⁺ to 1 mg/ml LDL protein, structural disintegration of LDL was observed in the scattering curves over a 72 hour period. This disintegration was parallelled by an increase in the R_G and I(0)/c parameters observed by neutron and X-ray Guinier analyses, and changes in the concentric shell-like structure of the lipids in the core as observed in the distance distribution functions. Structural changes included the aggregation and degradation of LDL, as confirmed by subsequent SDS-polyacrylamide gel elctrophoresis. These changes occurred after the antioxidant content of LDL had been fully depleted.

© EDP Sciences 1993