Structure of the O-specific polysaccharide of Hafnia alvei 23 having an oligosaccharide-phosphate repeating unit

Lipopolysaccharide (LPS) of Hafnia alvei 23 has an acid-labile O-specific polysaccharide (OPS) with a pentasaccharide-phosphate repeating unit containing D-Glc1P, D-GlcNAc, L-Fuc, 6-deoxy-D-talose (D-6dTal), 4-acetamido-4,6-dideoxy-D-glucose (D-Qui4NAc), and an O-acetyl group. A partially degraded OPS was obtained by hydrolysis of LPS with 0.25 M sodium acetate in aqueous 0.5% acetic acid. Fractionation of LPS on Sephadex G-200 in DOC buffer allowed isolation of long-chain LPS species which, together with OPS, were studied by methylation analysis, chemical degradations (O-deacetylation, dephosphorylation with 48% hydrofluoric acid, Smith degradation), and H-1 and C-13 NMR spectroscopy, including 2D COSY, TOCSY, NOESY, and II-detected H-1, C-13 heteronuclear single-quantum coherence (HSQC) experiments. The following structure of the repeating unit of OPS was established: [GRAPHICS] s appear only at an incubation temperature of 55 degrees C but at very low molar yield (about 14%) and lower regioselectivity.