Rotational diffusion of the low density lipoprotein-receptor complex

Abstract

Time-resolved phosphorescence anisotropy has been used to assess the rotational dynamics of human serum lipoproteins labeled with phosphorescent probes of high triplet yield. Covalent labeling of apolipoprotein B with erythrosin revealed the existence of segmental motion of labeled domains within the particle as well as global rotation of the particles. The binding of the low density lipoprotein to cell surface receptors resulted in a freezing of the global motion but the maintenance of faster motion of domains within the apolipoprotein. Labeling of the lipid phase of the low density lipoproteins with an eosinyl fatty acid also revealed the existence of two motions. The shorter time constant..