STRUCTURES OF GLUCOLIPIDS FROM THE MEMBRANE OF ACHOLEPLASMA-LAIDLAWII STRAIN A-EF22 .3. MONOGLUCOSYLDIACYLGLYCEROL, DIGLUCOSYLDIACYLGLYCEROL, AND MONOACYLDIGLUCOSYLDIACYLGLYCEROL

The structures of three glucolipids from the membrane of Acholeplasma laidlawii, strain A-EF22, were determined by high resolution H-1-NMR and C-13-NMR spectroscopy. The two most abundant glucolipids in this organism were shown to be 1,2-diacyl-3-0-(alpha-D-glucopyranosyl)-sn-glycerol (MGlcDAG) and 1,2-diacyl-3-0-[alpha-D-glucopyranosyl-(1 --> 2)-0-alpha-D-glucopyranosyl]-sn-glycerol (DGlcDAG). 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 1,2-diacyl-3-0-[alpha-D-glucopyranosyl-( 1 --> 2)-0-(6-0-acyl-alpha-D-glucopyranosyl)]-sn-glycerol. The existence of this lipid was detected by H-1-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.