The structure of the O-antigenic polysaccharide (PS) from the enteroaggregative Escherichia coli strain 522/C1 has been determined. Component analysis and (1)H and (13)C NMR spectroscopy techniques were used to elucidate the structure. Inter-residue correlations were determined by (1)H,(1)H-NOESY and (1)H,(13)C-heteronuclear multiple-bond correlation experiments. The PS is composed of pentasaccharide repeating units with the following structure: Analysis of NMR data reveals that on average the PS consists of four repeating units and indicates that the biological repeating unit contains an N-acetylgalactosamine residue at its reducing end. Serotyping of the E. coli strain 522/C1 showed it to be E. coli O178:H7. Determination of the structure of the O-antigen PS of the international type strain from E. coli O178:H7 showed that the two polysaccharides have identical repeating units. In addition, this pentasaccharide repeating unit is identical to that of the capsular polysaccharide from E. coli O9:K38, which also contains O-acetyl groups

NMR, structure, chemistry, clinical, correlation, strain, structural, capsular, polysaccharide, O-antigen, repeating unit, analysis, O antigen, group, Escherichia, Escherichia coli, determination, O-antigenic, O-antigenic polysaccharide, capsular polysaccharide, type, NMR spectroscopy, biological, polysaccharides, medicine, spectroscopy, structural studies, pentasaccharide, component, N-acetylgalactosamine, reducing, reducing end, serotyping, PDF, organic, bacteriology, O-acetyl, biological repeating unit, Enteroaggregative

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,4,2,4,2	Ac	175.4	23.1
3,4,2,4	aDGlcpN	99.1	53.8	70.4	79.7	71.3	60.4
3,4,2	aDGalpA	98.1	68.7	69.6	80.1	72.0	175.2
3,4	bDRibf	108.0	80.0	70.7	83.2	64.5
3	bDGalp	105.8	71.3	73.5	77.4	75.1	62.0
2	Ac	175.6	23.0
	bDGalpN	102.1	52.3	80.5	68.7	75.7	61.8


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,4,2,4,2	Ac	-	2.09
3,4,2,4	aDGlcpN	4.93	3.94	3.90	3.71	4.20	3.69-3.79
3,4,2	aDGalpA	5.23	3.92	4.09	4.37	4.48	-
3,4	bDRibf	5.34	4.32	4.25	4.07	3.68-3.86
3	bDGalp	4.48	3.54	3.76	4.03	3.72	3.77
2	Ac	-	2.06
	bDGalpN	4.62	4.05	3.92	4.18	3.76	3.77-3.81


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,4,2,4,2	Ac		23.1/2.09
3,4,2,4	aDGlcpN	99.1/4.93	53.8/3.94	70.4/3.90	79.7/3.71	71.3/4.20	60.4/3.69-3.79
3,4,2	aDGalpA	98.1/5.23	68.7/3.92	69.6/4.09	80.1/4.37	72.0/4.48	
3,4	bDRibf	108.0/5.34	80.0/4.32	70.7/4.25	83.2/4.07	64.5/3.68-3.86
3	bDGalp	105.8/4.48	71.3/3.54	73.5/3.76	77.4/4.03	75.1/3.72	62.0/3.77
2	Ac		23.0/2.06
	bDGalpN	102.1/4.62	52.3/4.05	80.5/3.92	68.7/4.18	75.7/3.76	61.8/3.77-3.81

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

*O[C@@H]1[C@@H](CO)O[C@H](O[C@H]2[C@@H](C(=O)O)O[C@H](O[C@H]3[C@H](O[C@H]4[C@@H](CO)O[C@@H](O[C@@H]5[C@@H](NC(C)=O)[C@H](*)O[C@H](CO)[C@@H]5O)[C@H](O)[C@H]4O)O[C@H](CO)[C@H]3O)[C@H](O)[C@H]2O)[C@H](NC(C)=O)[C@H]1O

876.768 g/mol (C₃₃H₅₂R₂N₂O₂₅, R = next and previous repeats, not counted in mol weight)