STRUCTURE OF THE O-SPECIFIC POLYSACCHARIDE OF HAFNIA-ALVEI PCM-1222 CONTAINING 2-AMINOETHYL PHOSPHATE

The O-specific polysaccharide of H. alvei strain PCM 1222 has a branch ed hexasaccharide repeating unit containing D-galactose, L-rhamnose, D -ribose, D-galacturonic acid, and 2-acetamido-2-deoxy-D-glucose in the ratios 1:2:1:1:1, as well as 2-aminoethyl phosphate (EtNP) and O-acet yl groups in nonstoichiometric amounts. The polysaccharide was modifie d by carboxyl reduction, O-deacetylation, and dephosphorylation with 4 8% hydrofluoric acid, the last reaction being accompanied by removal o f the lateral residue of beta-galactofuranose. The modified polysaccha rides were studied by methylation analysis and H-1 and C-13 NMR spectr oscopy, including 2D correlation spectroscopy (COSY), H-detected H-1, C-13 and H-1, P-31 heteronuclear multiple-quantum coherence (HMQC), 1D NOE, 2D rotating-frame NOE spectroscopy (ROESY), and 2D combined tota l correlation spectroscopy (TOCSY) and ROESY (TORO). The following str ucture of the O-deacetylated polysaccharide was established: [GRAPHICS ] In different batches of the polysaccharide, the content of EtNP vari ed from 0.35 to 0.55 and that of the O-acetyl groups from 0.05 to 0.4 per repeating unit. It was tentatively suggested that the O-acetyl gro up is located at position 4 of a rhamnosyl residue. (C) 1996 Elsevier Science Ltd.