Influence of Lipids on the Progesterone-Binding Affinity of Serum Albumin and α₁-Acid Glycoprotein

Abstract

If a highly purified commercial HSA* preparation is delipidated by extraction with chloroform-methanol at 4°, its binding affinity for progesterone increases about 2 1/2 fold. This was determined by equilibrium dialysis and evaluated by the method of Scatchard (Westphal, 1971; Fig. VI-4). Since pure albumin preparations contain small amounts of firmly bound fatty acids that are removed by organic solvents, addition of fatty acids to delipidated USA should inhibit interaction with progesterone. This was found when 5 moles of lauric acid were added per mole of nondelipidated or delipidated HSA; in either case, the nK value was reduced to less than half (Westphal, 1971: Fig. VI-4).