Rapid method for the isolation of lipoproteins from human serum by precipitation with polyanions

TLDR

The study presents a protocol for isolating lipoproteins from human serum using polyanion and divalent cation precipitation. Lipoproteins are precipitated from serum with polyanions (heparin, dextran sulfate, or sodium phosphotungstate) in the presence of MnCl₂ or MgCl₂, yielding reversible, selective, complete precipitation, followed by ultracentrifugation to separate low, very low, and high density fractions and further purify them. The method produces highly purified, immunologically pure lipoprotein fractions—low, very low, and high density—without contamination, and allows large‑scale preparation using only one preparative ultracentrifugation step.

Abstract

Procedures are described for the isolation of lipoproteins from human serum by precipitation with polyanions and divalent cations. A mixture of low and very low density lipoproteins can be prepared without ultracentrifugation by precipitation with heparin and either MnCl(2) alone or MgCl(2) plus sucrose. In both cases the precipitation is reversible, selective, and complete. The highly concentrated isolated lipoproteins are free of other plasma proteins as judged by immunological and electrophoretic methods. The low density and very low density lipoproteins can then be separated from each other by ultracentrifugation. The advantage of the method is that large amounts of lipoproteins can be prepared with only a single preparative ultracentrifugation. Polyanions other than heparin may also be used; when the precipitation of the low and very low density lipoproteins is achieved with dextran sulfate and MnCl(2), or sodium phosphotungstate and MgCl(2), the high density lipoproteins can subsequently be precipitated by increasing the concentrations of the reagents. These lipoproteins, containing small amounts of protein contaminants, are further purified by ultracentrifugation at d 1.22. With a single preparative ultracentrifugation, immunologically pure high density lipoproteins can be isolated from large volumes of serum.