A NEW FAMILY OF VERY LONG-CHAIN ALPHA,OMEGA-DICARBOXYLIC ACIDS IS A MAJOR STRUCTURAL FATTY ACYL COMPONENT OF THE MEMBRANE-LIPIDS OF THERMOANAEROBACTER-ETHANOLICUS 39E

A new family of alpha,omega-dicarboxylic, very long chain fatty acids was isolated and characterized from the lipids of thermophilic anaerob ic eubacterium, Thermoanaerobacter ethanolicus 39E. After the isolatio n of the membrane, the fatty acyl components were converted to methyl esters by acid-catalyzed methanolysis. The esterified fatty acyl compo nents were purified by a variety of chromatographic techniques and ana lyzed by gas chromatography (GC) and GC-mass spectrometry (MS). One of the isolated, esterified alpha omega dicarboxylic, very long chain fa tty acids Was characterized by mass spectrometry, H-1 and C-13 NMR spe ctroscopy and Fourier transform infrared spectroscopy. NMR experiments used included double quantum filtered correlated spectroscopy (DQF-CO SY) to establish spin connectivities and polarization transfer (DEFT) to measure the multiplicity of carbon signals split by protons. Based on these results, the structures of the other components could be dedu ced from their mass spectra. The new family of very long chain fatty a cid methyl esters are alpha,omega 13,16-dimethylheptacosanedioate dime thyl ester (C29), alpha,omega 13,16-dimethyloctacosanedioate dimethyl ester (C30), alpha,omega 13,16-dimethylnonacosanedioate dimethyl ester (C31), and alpha omega 13,16-dimethyltriacotanedioate dimethyl ester (C32). This family of fatty acids make up about 40% of fatty acyl comp onents of the membrane of Thermoanaerobacter ethanolicus 39E. Almost a ll (> 90%) of the very long chain, alpha,omega dicarboxylic fatty acid was alpha,omega 13,16-dimethyloctacosanedioic acid. A careful analysi s of the structures of the alpha,omega-dicarboxylic acid strongly impl ies that the synthetic mechanism for formation is by tail-to-tail (ome ga)coupling of regular iso-branched fatty acids across opposite sides of the membrane.