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. Author manuscript; available in PMC: 2014 Apr 11.
Published in final edited form as: Innate Immun. 2013 Jun 28;20(3):269–282. doi: 10.1177/1753425913490534

Figure 3.

Figure 3

Negative-ion MALDI–MS mass spectra profiles of lipid A preparations. Lipid A was isolated from E. coli lpxL mutant strain MLK217 grown (A) at 30°C, (B) at 37°C and (C) at 42°C after 14 h growth. Earlier reports showed that E. coli lpxL mutant strain MLK217 lacks a lauric acid (12:0 fatty acid, ΔM=−182 u) that was located at the secondary 2′-O-position of an acyloxy bond to the primary O-linked 3-hydroxymyristic acid located on the distal glycosamine in the 3′-position in the corresponding wild type strain. Lipid A mass peaks of the lpxL mutant strain are annotated with the assigned composition of fatty acids. Lipid A acylation patterns and acyl group compositions vary significantly with temperature. The lipid A species at m/z 1541.8 (B, annotated with #) corresponds to an anhydro lipid A species, i.e. 4×14:0(3-OH), 16:1, –H2O.