Figure 1: MS analysis of Bradyrhizobium BTAi1 lipid A.

(a) Mass spectrum of carboxy-methylated hopanoid derivative as obtained by GC-MS analysis of the lipid A; the hopanoid numbering and fragmentation pattern are reported in the inset. (b) Reflectron MALDI TOF mass spectrum in positive ion more of the lipid A from Bradyrhizobium BTAi1; ion peaks are present as Na+ adducts. (c) MALDI TOF/TOF MS2 analysis of the hepta-acylated lipid A species at m/z 3135.36 (P: parent ion). The lipid A is sketched, letters refer to the ions generated in the MS/MS spectrum. The square indicates the acetyl group, the hopanoid is schematically indicated with the pentacyclic triterpenoid moiety (DAG, 2,3-diamino-2,3-dideoxy-D-glucopyranose; GalA, galacturonic acid; Man, mannose; Hopa, hopanoid).