Fatty acids hexaacyl lipid

A pentaacyl lipid A is also present in P. aeruginosa (77) (Fig. 11 A). Here, the main lipid A species contains a total of five fatty acids, and a minor hexaacyl species (Fig. 1 IB) corresponds structurally to lipid A of C. viola-ceum (Fig. 10). The prominent pentaacyl component, which makes up approximately 75% (w/w) of P. aeruginosa lipid A, encompasses three structural forms that all possess the same /H1 — 6)-linked GlcpN backbone, but with only three (primary) 3-hydroxy fatty acids attached to positions 3, 2, 3, and 2 (Fig. 11A). These structural forms differ from each other by the 3-0-acylation of each of the two amide-linked 12 0(3-OH) residues by the secondary acyl groups 12 0 or 12 0(2-OH), as indicated by the dashed lines. Of the four conceivable structural types, the one bearing two 12 0(2-OH) residues is not present. 

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