The structure of the O-antigenic polysaccharide from enterotoxigenic Escherichia coli O147 has been determined by NMR spectroscopy, and component and methylation analyses. The sequence of the sugar residues could be determined by NOESY and heteronuclear-multiple-bond-connectivity NMR experiments. It is concluded that the polysaccharide is composed of tetrasaccharide repeating units with the following structure: →4)-β-D-GalpA-(1→3)-β-D-GalpNAc-(1→2)-α-L-Rhap-(1→2)-α-L-Rhap-(1→, where Rha represents 6-deoxymannose. The O-antigen of E. coli O147 is identical to the repeating unit of Shigella flexneri serotype 6 lipopolysaccharide, except that the latter contains an O-acetyl group at C3 of the rhamnosyl residue substituted by the N-acetylgalactosamine residue. Immunochemical analyses using a monoclonal antibody specific for the S. flexneri serotype 6 O-antigen showed an identical reactivity with both lipopolysaccharides

Lipopolysaccharide, LPS, structure, structural, polysaccharide, O-antigen, Escherichia, Escherichia coli, determination, enterotoxigenic, O-antigenic, O-antigenic polysaccharide, Shigella flexneri, structural determination

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,4,2	aLRhap	101.7	79.7	70.7	73.3	69.9	17.5
3,4	aLRhap	100.6	79.3	70.7	73.0	69.9	17.5
3	bDGalpA	105.1	71.0	73.9	77.0	74.4	173.0
2	Ac	175.5	23.3
	bDGalpN	103.6	52.5	81.0	68.5	75.5	61.8


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,4,2	aLRhap	5.15	4.11	3.82	3.35	3.66	1.24
3,4	aLRhap	5.32	4.07	3.86	3.39	3.63	1.23
3	bDGalpA	4.49	3.61	3.80	4.33	4.27	-
2	Ac	-	2.02
	bDGalpN	4.70	4.01	3.88	4.22	3.66	3.77


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,4,2	aLRhap	101.7/5.15	79.7/4.11	70.7/3.82	73.3/3.35	69.9/3.66	17.5/1.24
3,4	aLRhap	100.6/5.32	79.3/4.07	70.7/3.86	73.0/3.39	69.9/3.63	17.5/1.23
3	bDGalpA	105.1/4.49	71.0/3.61	73.9/3.80	77.0/4.33	74.4/4.27	
2	Ac		23.3/2.02
	bDGalpN	103.6/4.70	52.5/4.01	81.0/3.88	68.5/4.22	75.5/3.66	61.8/3.77

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*O[C@H]1[C@H](O[C@H]2[C@H](O[C@H]3[C@@H](C(=O)O)O[C@@H](O[C@@H]4[C@@H](NC(C)=O)[C@H](*)O[C@H](CO)[C@@H]4O)[C@H](O)[C@H]3O)O[C@@H](C)[C@H](O)[C@H]2O)O[C@@H](C)[C@H](O)[C@H]1O

671.602 g/mol (C₂₆H₄₁R₂NO₁₉, R = next and previous repeats, not counted in mol weight)