Unusual Phospholipid Research Articles

Incorporation and subcellular distribution of an unnatural phospholipid base-analog, N-isopropylethanolamine, in rat liver

An unnatural phospholipid, phosphatidyl- N-isopropylethanolamine, was isolated from rat liver after intraperitoneal injections of N-isopropylethanol amine; it was identified on the basis of enzymic, chemical, and Chromatographic analyses. Although this phospholipid was formed at the expense of phosphatidylcholine and phosphatidylethanolamine, its fatty acid composition did not resemble either of these lipids. Microsomes, mitochondria, and plasma membranes contained significant amounts (up to 9%) of this unusual phospholipid. Radioisotope incorporation experiments suggest that the N-isopropylethanolamine containing phospholipid is rapidly equilibrated between microsomes and mitochondria and more slowly with surface membranes.

Zymogen secretion and phospholipid metabolism in the pancreas. Phospholipids of the zymogen granule.

1. Acetylcholine produced a fivefold increase in the specific radioactivity of phosphatidylinositol in guinea-pig pancreas slices incubated in the presence of [(32)P]-orthophosphate, but did not affect the specific radioactivity of the terminal phosphate of ATP. 2. The secretagogues acetylcholine and pancreozymin had no direct effect on the enzymes of phosphatidylinositol biosynthesis in guinea-pig pancreas homogenates. 3. Pancreozymin in vivo increased the incorporation of [(32)P]orthophosphate into phosphatidylinositol but not into phosphatidylcholine, phosphatidylethanolamine or phosphatidylserine. 4. The zymogen-granule membrane contained no unusual phospholipids or lysophospholipids, although its high cholesterol/phospholipid ratio resembled that of plasma membrane. 5. Phospholipase A activity during fractionation sometimes produced lysophospholipids in mitochondrial, microsomal and zymogen-granule fractions.

Semi-lyso- bis-phosphatidic acid: an unusual phospholipid isolated from rabbit lung

An unusual phospholipid was isolated from a total lipid extract of rabbit lung tissue by chromatography on columns of silica gel H. It accounted for about 0.2 per cent of the total phospholipids. The results of alkaline hydrolysis, periodate oxidation and acetolysis showed that the lipid possessed the structure of a semi-lyso- bis-phosphatidic acid. Its chromatographic properties in four different chromatographic systems supported the proposed structure. It contained mainly palmitic acid (24%), oleic acid (38%) and linoleic acid (20%). The position of the free hydroxyl group in the molecule is discussed.