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1. Deacylation of phosphatidylcholine by the lipolytic acyl hydrolase enzyme in homogenates of potato tubers was stimulated by endogenous free fatty acids in the homogenates. 2. Partially purified enzyme preparations were inactive in the absence of surface active agents. 3. The fatty acid-stimulated enzymic deacylation of phosphatidylcholine showed a pH optimum between 5.5 and 6.0 and was reversed by bovine serum albumin. 4. Free fatty acids were more effective than other lipids and surface active compounds studied. 5. Long-chain cis-unsaturated fatty acids were most effective. 6. Enzymic hydrolysis of phosphatidylethanolamine showed a similar stimulation by free fatty acids but hydrolysis of lyso-phosphatidylcholine, phosphatidyiglycerol, phosphatidic acid galactolipids or monoglycerides was not stimulated. 7. Similar stimulation by linoleic acid of the enzymic deacylation of membrane-bound phospholipid was observed and found to be prevented by bovine serum albumin. 8. Electron microscope studies suggested that free fatty acids had a marked effect on the physical state of phosphatidylcholine in aqueous dispersions. [ABSTRACT FROM AUTHOR]

1. The phospholipids of rabbit erythrocytes were separated by thin-layer chromatography on silica gel HR and determined quantitatively by the molybdenum blue method. Prior to thinlayer chromatography phosphatidic acid and phosphatidyl inositol were concentrated by column chromatograph. 2. The total phospholipid contents were 313 ± 27 amoles per erythrocyte and 289 ± 13 amoles per ghost. The proportions of the individual phospholipids of erythrocytes in moles % were 36.3 of phosphatidyl choline, 32.6 of phosphatidyl ethanolamine, 15.7 of sphingomyelin, 12.4 of phosphatidyl serine, 1.6 of phosphatidic acid, 1.3 of phosphatidyl inositol, and <0.1 of lysophosphatidyl choline. The same distribution was obtained in ghosts with the exception of a significantly higher concentration of sphingomyelin. 3. The fatty acid composition of phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine, ceramide trisaccharide, and sphingomyelin was analysed by gas-liquid chromatography after the lipids had been fractionated by preparative thin-layer chromatography. 4. For identification of the fatty a acids, their methylesters were isolated on silica gel G-silver nitrate plates according to degree of saturation. 5. Typical of sphingotipids were the tow concentration of linoleic acid, the absence of arachidonic acid, the presence of lignoceric acid and the very high concentration of nervonic acid. 6. Phosphatidyl choline and phosphatidyl ethanolamine were hydrolysed by phospholipase A (ophiophagus hannah) in order to analyse the fatty acid distribution of the two positions. In position 1 of phosphatidyl choline and phosphatidyl ethanolamine the saturated fatty acids amounted to 83.6% and 65.6%, respectively. Unsaturated fatty acids, especially oleic acid and linofeic acid, also occurred in position 1. These acids were the main components in position 2. [ABSTRACT FROM AUTHOR]

Caries incidence was generally lower in rats fed a cariogenic diet that contained four different oils and fats at a 9% level than in those fed a diet with a 3% level of the same oil or fat. The amount of linoleic acid in pooled samples of dentin and enamel extracted from the molars and incisors was related to the amount of linoleic acid in the diet. [ABSTRACT FROM AUTHOR]