Structural analysis of two glycosphingolipids from the lipopolysaccharide-lacking bacterium Sphingomonas capsulata

Abstract

Two glycosphingolipids, GSL-1 and GSL-3, were isolated from Sphingomonas capsulata and studied by methylation analysis, laser desorption mass spectrometry, and 1H and 13C NMR spectroscopy, including two-dimensional 1H,1H COSY and heteronuclear 13C,1H COSY experiments. GSL-1 and GSL-3 differ in their carbohydrate part, their structures being α-D-GlcpA-(1→1)- Cer and α-D-Galp-(1→6)-α-D-GlcpN(1→4)-α-D-GlcpA(1→1)Cer, respectively. Variations occur in the ceramide of GSL-1 and GSL-3, both having the same long-chain bases, erythro-2-amino-1,3-octadecanediol (sphinganine), (13Z)- erythro-2-amino-13-eicosene-1,3-diol and (13Z)-erythro-2-amino-13,14- methylene-1,3-eicosanediol, in the ratios 2.6 : 1:3.5 in GSL-1 and 1 : 1.2: 1.5 in GSL-3. All bases are quantitatively substituted by amide-linked (S)-2- hydroxymyristic acid.