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 electrospray ionization-mass spectrometry (ESI/MS), we have redetermined the stereochemical configuration of some natural and synthetic phosphatidylglycerols (PG). For this purpose, the synthetic and natural PG were converted to their bis-3,5-dinitrophenylurethanes (DNPU), which were separated by HPLC using two columns having chiral phases of opposite configuration, (R)-(+)- and (S)-(-)-1-(1-naphthyl)ethylamine polymers. The molecular species were identified by on-line negative-ion ESI/MS. Absolute configurations of the resolved peaks were assigned by comparison with the elution order of the corresponding 1(3)-monoacyl-sn-glycerol enantiomers as bis-DNPU derivatives on the same column. The results 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 phospholipase D in the tissues. On the other hand, the PG derived from egg yolk phosphatidylcholine and glycerol by transphosphatidylation with cabbage phospholipase D was a mixture of 45% R,S isomers (1, 2-diacyl-sn-glycero-3-phospho-1'-sn-glycerols) and 55% R,R isomers (1,2-diacyl-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 direct and unambiguous information about the configuration, identity, and quantity of molecular species in natural and synthetic PG.
Itabashi
Y
Y
C. H. Best Institute, University of Toronto, 112 College Street, Toronto, Ontario, M5G 1L6, Canada.
Kuksis
A
A
D001937:Brassica / Q000201:enzymology; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000737:chemistry; D005989:Glycerides / Q000302:isolation & purification; D008055:Lipids / Q000737:chemistry; D013058:Mass Spectrometry; D008968:Molecular Conformation; D015394:Molecular Structure; D010715:Phosphatidylglycerols / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D010739:Phospholipase D / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry; D010944:Plants / Q000737:chemistry; D013237:Stereoisomerism; D014520:Urethane / Q000031:analogs & derivatives / Q000737:chemistry
D005989:Glycerides; D008055:Lipids; D010715:Phosphatidylglycerols; D010743:Phospholipids; D014520:Urethane; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; C064040:dilinoleoylphosphatidylglycerol; D010739:Phospholipase D