BIS(MONOACYLGLYCERO)PHOSPHATE FROM PC12 CELLS, A PHOSPHOLIPID THAT CAN COMIGRATE WITH PHOSPHATIDIC-ACID - MOLECULAR-SPECIES ANALYSIS BY FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY

Phospholipids from pheochromocytoma (PC12) cells were purified by one-dimensional thin-layer chromatography (TLC). Material corresponding in R(F) to phosphatidic acid (PA) was analyzed by fast atom bombardment mass spectrometry (FAB). The molecular ions of the major constituents corresponded in mass to phosphatidylglycerols (PG), which, however, have a lower R(F) value. Analysis of the mass spectra demonstrated that this material consists of bis(monoacylglycero)phosphates (BMP, lysobisphosphatidic acid), a structural isomers of PG. Linked scans of individual molecular ions indicate that BMP from PC12 cells is esterified almost exclusively with monounsaturated (16 : 1 and 18 : 1) and polyunsaturated (20 : 4 and 22 : 6) fatty acids. One of the two major molecular species contains two monounsaturated (18 : 1/18 : 1), while the other contains both a monounsaturated (18 : 1) and a polyunsaturated (22 : 6) fatty acid ester. FAB in combination with TLC is ideally suited for analysis of molecular species of phospholipids.