Structure of lipid A component of Rhizobium leguminosarum bv. phaseoli lipopolysaccharide. Unique nonphosphorylated lipid A containing 2-amino-2-deoxygluconate, galacturonate, and glucosamine.

摘要: The structure of lipid A from the lipopolysaccharide Rhizobium leguminosarum bv. phaseoli (wild type strain CE3) was investigated by alkylation analysis, nuclear magnetic resonance spectroscopy, and electrospray fast atom bombardment mass spectrometry de-O-acylated A. carbohydrate backbone shown to be a trisaccharide containing galacturonic acid, glucosamine, unique sugar 2-amino-2-deoxygluconic previously unreported in lipopolysaccharides. Nuclear spectroscopy ethylation analyses revealed that acid is alpha-1,4-linked while amino aldonic residue, which may exist as 1,5-lactone, attached an aglycone glucosamine and, thus, occupies reducing end molecule. resulting hydrophilic analogous commonly observed bisphosphorylated disaccharide enteric bacterial lipopolysaccharides both nonreducing ends carry negatively charged substituents. fatty acids R. are O- N-acyl substituents 2-aminogluconate. All hydroxylated consisting 3-hydroxymyristate (3-OH-C14.0), 3-hydroxypentadecanoate (3-OH-C15.0), 3-hydroxypalmitate (3-OH-C16.0), 3-hydroxystearate (3-OH-C18.0), 27-hydroxyoctacosanoate (27-OH-C28.0) approximate mole ratio 3:0.2:1:0.6:1. Unlike As bacteria, lacks 3-acyloxyacyl substituents; however, long chain 27-hydroxy carries ester-linked beta-hydroxybutyrate at position. Fast demonstrated presence 2 molecular species differ 28 units due heterogeneity two amide linkages. One amide-linked 3-OH-C14.0 3-OH-C16.0; second 3-OH-C18.0. Each also exists aldonolactone, yielding ions ((M+H)+)-18. further distinguishes As.