Identification of phospholipid molecular species containing two fatty acyl chains differing by 2 Da by negative-ion fast-atom bombardment with mass-analyzed ion kinetic energy analysis



Isomeric glycerophosphatidylcholine molecular species containing fatty acyl chains differing by 2 Da (1-stearoyl-2-oleoyl- and 1-oleoyl-2-stearoyl-sn-glycero-3-phosphocholine) can be identified by the determination of trhe fatty acid chain esterified to the sn-1 position in the glycerol backbone based on the electric sector voltage differences of [M-86-R2COOH] anions derived from phosphatidic acid parent ions (M minus choline group) produced by negative-ion fast-atom bombardment combined with mass-analyzed ion kinetic evergy analyses. Three volt differences can be observed in the spectra. The study further demonstrates that this approach is also effective in distinguishing such molecular species as isomers of glycerophosphatidic acid, glycerophosphatidyl-ethanolamine and glycerophosphatidylserine and in characterizing the molecular species, differing by 2 Da, of the bovine brian glycerophosphatidylserine (1-stearoyl-2-oleoyl-sn-glycero-3-phosphoserine) and the rabbit kidney glycerophos-phatidylethanolamine (1-oleoyl-2-linoleoyl-sn-glycero-3-phosphoethanolamine).