Structural analyses of the novel phosphoglycolipids containing the unusual very long bifunctional acyl chain, alpha,omega-13,16-dimethyloctacosanedioate in Thermoanaerobacter ethanolicus

Abstract

Novel membrane lipids containing the unusual very long chain fatty acid, α,ω-13,16-dimethyloctacosanedioate dimethyl ester (DME C30) was isolated and purified from thermophilic anaerobic eubacterium, Thermoanaerobacter ethanolicus. Structures of the lipids containing the bifunctional fatty acyl components were proposed by various analyses such as 1H, 13C, 31P nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, gas chromatography/mass spectrometry (GC/MS) and fast atom bombardment mass spectrometry (FAB/MS). Combined with the GC/MS, 1H and 13C NMR data, we confirmed that the head groups of the lipids contained the glycerol and/or glucosamine molecules. 31P NMR spectrum also showed that the lipids contained phosphate in a phosphodiester linkage. The proposed structures of these novel lipid components were the ones in which two head groups were linked by the membrane spanning fatty acyl component (DME C30) and regular chain fatty acids on glycerol moiety of each head group.