Influence of the products of phospholipolysis of phosphatidylcholine on micellar solubilization of fatty acids in the presence of bile salts.

1. The solubility of fatty acids in aqueous solutions containing bile salts and lysolecithin at pH values between 2-0 and 7-4 was studied. Both the 1-acyl and 2-acyl isomers of lysolecithin increased the solubility of fatty acids to the same extent, the order of solubility being linoleic greater than oleic greater than elaidic greater than palmitic greater than stearic. 2. The influence of the products of phospholipolysis of lecithin on palmitic acid solubility was determined. On a molar basis, lysolecithin was more effective than were bile salts in promoting the solubilization of the fatty acid. 3. In bile salt solutions in which the phospholipid concentration was constant on a molar basis, in solubility of palmitic acid decreased linearly with the progressive replacement of lecithin by lysolecithin. Palmitic acid was solubilized to the same extent on replacing lecithin with lysolecithin on a constant weight basis. 4. In bile salt solution containing lysolecithin and oleic acid in equimolar amounts, the solubility of palmitic acid was similar to that in bile salt solution containing lecithin in equivalent proportion. 5. The results are discussed in relation to the action of phospholipolytic activity on the intestinal absorption of fatty acids in sheep.