Abstract
The interaction of human serum low-density lipoproteins (LDL) with various types of prostaglandins (PG) was studied using equilibrium dialysis, steady-state fluorescence polarization spectroscopy and photolabeling methods. Low concentrations (10 −13-10 −19 M) of PGE 1 and PGF 2α were shown to induce specific rearrangements of the lipids on the LDL surface, whereas the closely related PGE 2 and PGF 1α had no effect. With fluorescent labeled LDL, the PGE 1-induced changes of the steady-state fluorescence polarization ( P) were shown to be time- and concentration-dependent, saturable and reversible. However, equilibrium dialysis revealed a very low binding capacity of LDL for PGE 1 (approx. 1 prostaglandin molecule per 600 LDL particles). Approximately the same PGE 1 concentration was sufficient to cause maximal changes of P, to enhance the binding to apolipoprotein B of a photoreactive sphingomyelin analogue inserted into the LDL surface and to alter the thermal phase behavior of the LDL surface lipids. It is proposed that the LDL surface rearrangement caused by prostaglandins is due to the interaction of prostaglandins with apolipoprotein B, resulting in formation of short-lived complexes. The mechanism of this interaction is discussed in terms of the non-equilibrium ligand-receptor interaction model proposed earlier to explain the interaction of prostaglandins with high-density lipoproteins (Bergelson, L.D. et al. (1987) Biochim. Biophys. Acta 921, 182–190). It is suggested that direct prostaglandin-lipoprotein interactions may play a role in the homeostasis of cholesterol.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call