Structure Determination of Lipid A with Multiple Glycosylation Sites by Tandem MS of Lithium-Adducted Negative Ions.

FLAT is a tandem mass spectrometric technique that can be used to rapidly generate spectral information applicable for structural elucidation of lipids like lipid A from Gram-negative bacterial species from a single bacterial colony. In this study, we extend the scope and capability of FLAT by tandem MS fragmentation of lithium-adducted molecular lipid A anions and fragments (FLAT) that provides additional structural and diagnostic data from FLAT samples allowing for the discrimination of terminal phosphate modifications in a variety of pathogenic and environmental species. Using FLAT, we elucidated the lipid A structure from several bacterial species, including novel structures from arctic bacterioplankton of the and genera that favor 4-amino-4-deoxy-l-arabinopyranose (Ara4N) modification at the 1-phosphate position and that demonstrate double glycosylation with Ara4N at the 1 and 4' phosphate positions simultaneously.