Structure of a new acidic O-antigen of Proteus vulgaris O22 containing O-acetylated 3-acetamido-3,6-dideoxy-D-glucose

The acidic O-specific polysaccharide of Proteus vulgaris O22 was studied us ing H-1 and C-13 NMR spectroscopy, including 2D COSY, TOCSY, NOESY, and H-d etected H-1,C-13 heteronuclear multiple-quantum coherence (HMQC) experiment s, and the following structure for the branched pentasaccharide repeating u nit was established: alpha-D-Quip3NAc2,4Ac(2) 1 down arrow 2 --> 3)-beta-D-GlcpNAc-(1 --> 3)-bet a-L-Rhap-(1 --> 4)-alpha-L-Rhap-(1 --> 4)-beta-D-GlcpA-(1 --> where Qui3NAc is 3-acetamido-3,6-dideoxyglucose, O-acetylation of QuiNAc at position 4 is stoichiometric and at position 2 nonstoichiometric. Serologi cal relationships of P. vulgaris O22 with some other Proteus strains were s ubstantiated on the level of the O-antigen structures. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.