Antigenic polysaccharides of bacteria: 41. Structures of the O-specific polysaccharides of <Emphasis Type="Italic">Shigella dysenteriae</Emphasis> types 4 and 5 revised by NMR spectroscopy
(1) Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, Moscow, 119991, Russia;(2) TEDA School of Biological Sciences and Biotechnology, Nankai University, 23 HongDa st., TEDA, Tyan-jin, 300457, Chinese People’s Democratic Republic;(3) Tianjin Key Laboratory for Microbial Functional Genomics, TEDA College, Nankai University, 23 HongDa st., TEDA, Tyan-jin, 300457, Chinese People’s Democratic Republic
Abstract:
The earlier established structures of the acidic O-specific polysaccharides from two typical strains of the Shigella dysenteriae bacterium were revised using modern NMR spectroscopy techniques. In particular, the configurations of the glycosidic linkages of GlcNAc (S. dysenteriae type 4) and mannose (S. dysenteriae type 5) residues were corrected. In addition, the location of the sites of non-stoichiometric O-acetylation in S. dysenteriae type 4 was determined: the lateral fucose residue was shown to be occasionally O-acetylated; also, theposition of the O-acetyl group present at the stoichiometric quantity in S. dysenteriae type 5 was corrected. The revised structures of the polysaccharides studied are shown below. The known identity of the O-specific polysaccharide structures of S. dysenteriae type 5 and Escherichia coli O58 was confirmed by 13C NMR spectroscopy and, hence, the structure of the E. coli O58 polysaccharide should be revised in the same manner.
L-Rhap3Rlac2Ac is 2-O-acetyl-3-O-(R-1-carboxyethyl]-L-rhamnose