REASSESSMENT OF STEREOCHEMICAL CONFIGURATION OF NATURAL PHOSPHATIDYLGLYCEROLS BY CHIRAL-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND ELECTROSPRAY MASS-SPECTROMETRY

Using chiral-phase high-performance liquid chromatography (HPLC) and e lectrospray ionization-mass spectrometry (ESI/MS), we have redetermine d the stereochemical configuration of some natural and synthetic phosp hatidylglycerols (PG), For this purpose, the synthetic and natural PG were converted to their bis-3,5-dinitrophenylurethanes (DNPU), which w ere separated by HPLC using two columns having chiral phases of opposi te configuration, (R)-(+)- and (S)-(-)-1-(1-naphthyl)ethylamine polyme rs. The molecular species were identified by on-line negative-ion ESI/ MS. Absolute configurations of the resolved peaks were assigned by com parison with the elution order of the corresponding 1(3)-monoacyl-sn-g lycerol enantiomers as bis-DNPU derivatives on the same column, The re sults clearly showed that the PG from cabbage leaf lipids and soybean phospholipids consisted of single R,S isomers (1,2-diacyl-sn-glycero-3 -phospho-1'-sn-glycerols), despite the presence of nonstereospecific p hospholipase D in the tissues. On the other hand, the PG derived from egg yolk phosphatidylcholine and glycerol by transphosphatidylation wi th cabbage phospholipase D was a mixture of 45% R,S isomers (1,2-diacy l-sn-glycero-3-phospho-1'-sn-glycerols) and 55% R,R isomers (1,2-diacy l-sn-glycero-3-phospho-3'-sn-glycerols). The PG from Escherichia coli lipids was a mixture of 89% R,S and 11% R,R isomers. The present study demonstrates that chiral-phase HPLC and negative-ion ESI/MS provide d irect and unambiguous information about the configuration, identity, a nd quantity of molecular species in natural and synthetic PG. (C) 1997 Academic Press.