Removal of hydrophobic compounds from biological fluids by a simple method

A hydrophobic column-packing material (Lipidex 1000) was utilized to remove unbound as well as protein-bound hydrophobic molecules from aqueous solutions in a controlled manner by choice of flow rate and temperature according to the protein-lipid interaction kinetics. The adsorbed compounds were readily recovered upon change of eluant from buffer to methanol. It could be used to eliminate steroids from water solutions or to accomplish separation of protein-bound from unbound steroids at 0–4°C. At 45°C bound steroid ligand was also removed from albumin, corticosteroid-binding globulin, and sex hormone-binding globulin. These proteins retained their capacity to bind ligand after passing the column. Scatchard analysis of steroid hormone receptors in cytosol from pig seminal vesicles suggested the occurrence of “positive cooperativity”; however, chromatography of the cytosol on Lipidex 1000 prior to the incubation with ligand removed lipid droplets in the sample and resulted in a linear Scatchard plot. Since the gel has a high capacity for adsorption of lipids and steroids, large sample volumes can be used in order not to change the ion composition of the sample. Moreover, no adverse affects on the proteins investigated were observed, and the method is therefore likely to be useful not only in lipid research, but also in protein-biochemical work.