Structures of glucolipids from the membrane of Acholeplasma laidlawii strain A-EF22. III. Monoglucosyldiacylglycerol, diglucosyldiacylglycerol, and monoacyldiglucosyldiacylglycerol

Abstract

The structures of three glucolipids from the membrane of Acholeplasma laidlawii, strain A-EF22, were determined by high resolution 1H-NMR and 13C-NMR spectroscopy. The two most abundant glucolipids in this organism were shown to be 1,2-diacyl-3- O-(α- d-gluco-pyranosyl)- sn-glycerol (MG1cDAG) and 1,2-diacyl-3- O-[α- d-glucopyranosyl-(1 → 2)- O-α- d-glucopyranosyl]- sn-glycerol (DGIcDAG). These structures agree with those determined previously by chemical analyses of the two most abundant glucolipids synthesized by the B strain of A. laidlawii. The structure of a newly discovered glucolipid in A. laidlawii strain A-EF22 was also determined. This lipid is an acylated derivative of DGlcDAG with the structure l,2-diacyl-3- O-[α- d-glucopyranosyl-(1 → 2)- O-(6- O-acyl-α- d-glucopyranosyl)]- sn-glycerol. The existence of this lipid was detected by 1H-NMR spectroscopy in preparations of MGlcDAG which had been judged by thin-layer chromatography to be pure. The biosynthesis of the glucolipids and their role in the metabolic lipid regulation are briefly discussed.