title: Gas chromatography/tandem mass spectrometry as an analytical tool for the identification of fatty acids.
abstract: Structures of fatty acids present at very low quantities in mycobacteria are difficult to determine. A commonly used strategy is to introduce heteroatoms into functional groups by chemical means before subjecting them to gas chromatography/tandem mass spectrometry (GC/MS/MS) analysis. Routinely used methods give very low abundance diagnostic ions leading to ambiguities in structural conclusions. GC/MS/MS associated with electron capture ionization of pentafluorobenzyl esters was used to study very complex mixtures of fatty acids from Mycobacterium fallax and M. aurum. The charge-remote fragmentation of fatty acid carboxylate anions was used for structure determination at the nanogram level of a large number of unsaturated, branched, and cyclopropane-containing fatty acids. Some of them have not been observed previously in these Mycobacteria. On the basis of these studies, biosynthetic pathways of unsaturated, branched, and cyclopropane-containing fatty acid are proposed.
mesh_terms: D004563:Electrochemistry; D005227:Fatty Acids / Q000032:analysis* / Q000737:chemistry; D005231:Fatty Acids, Unsaturated / Q000032:analysis / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008745:Methylation; D015394:Molecular Structure; D009161:Mycobacterium / Q000737:chemistry*
chemical_list: D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated