Lipopolysaccharides (LPS) of several Pseudomonas aeruginosa rough mutant strains appear to have a common core oligosaccharide containing Glc, GAIN, L-glycero-Dmanno-heptose (L,D-Hep), 3-deoxy-D-manno-octulosonic acid (Kdo), and, as a very peculiar feature, the amino acid alanine [1,2]. Recently, structural analysis of the complete core oligosaccharide of the R5 mutant has been reported by Masoud et al. [3]. Based on a general NMR strategy and in contrast to a previous finding [2], the authors have identified two L-glycero-D-manno-heptose residues in the inner core region. By using GLC-MS and chemical derivatization procedures we also identified two heptosyl residues in the LPS of the the rough mutant strain P. aeruginosa PAC605. In addition, we have now found the hitherto unknown 7-O-carbamoyl-L-glycero-D-manno-heptose in all rough mutant and wild type LPS of P. aeruginosa investigated. 7-O-Carbamoyl-Lglycero-D-manno-heptose was also identified in LPS from related Pseudomonas species, such as P. fluorescens and P. syringae, and, thus, appears to be a characteristic and diagnostic marker for Pseudomonas spp. of a newly classified RNA group I [4].
For the GLC-MS [carried out on a 30-m HP-5 ® fused silica capillary column