The structure of the O-antigen polysaccharide of the lipopolysaccharide from the enteroinvasive Escherichia coli O136 has been elucidated. The composition of the repeating unit was established by sugar and methylation analysis together with 1H and 13C NMR spectroscopy. Two-dimensional nuclear Overhauser effect spectroscopy (NOESY) and heteronuclear multiple-bond correlation experiments were used to deduce the sequence. The absolute configuration for the nonulosonic acid (NonA) could be determined using spin-spin coupling constants, 13C chemical shifts and NOESY. The anomeric configuration of the NonA was determined via vicinal and geminal 13C,1H coupling constants. The structure of the repeating unit of the polysaccharide from E. coli O136 is as follows, in which β-NonpA is 5,7-diacetamido-3,5,7, 9-tetradeoxy-Lglycero-β-Lmanno-nonulosonic acid: -4)-β-NonpA-(2-4)-β-D-Galp-(1-4)-β-D-GlcpNAc-(1-

Lipopolysaccharide, NMR, LPS, structure, strain, structural, polysaccharide, O-antigen, Escherichia, Escherichia coli, determination, O-antigenic, O-antigenic polysaccharide, nonulosonic acid, elucidation, Structure determination, Enteroaggregative, Enteroinvasive

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6	C7	C8	C9
4,4,5	Ac
4,4,7	Ac
4,4	bXPsep	172.9	102.7	36.0	73.5	45.9	75.0	54.5	69.5	17.6
4	bDGalp	103.9	72.4	72.9	73.3	76.2	61.8
2	Ac	?	23.4
	bDGlcpN	99.5	55.9	73.6	80.1	75.6	61.1


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6	H7	H8	H9
4,4,5	Ac
4,4,7	Ac
4,4	bXPsep	-	-	1.74-2.63	4.06	4.32	3.75	3.96	4.11	1.16
4	bDGalp	4.48	3.58	3.66	4.51	3.72	3.69-3.69
2	Ac	-	2.02
	bDGlcpN	4.70	3.70	3.71	3.68	3.59	3.85-4.00


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6	C7/H7	C8/H8	C9/H9
4,4,5	Ac
4,4,7	Ac
4,4	bXPsep			36.0/1.74-2.63	73.5/4.06	45.9/4.32	75.0/3.75	54.5/3.96	69.5/4.11	17.6/1.16
4	bDGalp	103.9/4.48	72.4/3.58	72.9/3.66	73.3/4.51	76.2/3.72	61.8/3.69-3.69
2	Ac		23.4/2.02
	bDGlcpN	99.5/4.70	55.9/3.70	73.6/3.71	80.1/3.68	75.6/3.59	61.1/3.85-4.00

The spectrum also has 1 signal at unknown position (not plotted).

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

681.645 g/mol (C₂₇H₄₃R₂N₃O₁₇, R = next and previous repeats, not counted in mol weight)