The lipopolysaccharide (LPS) of Escherichia coli 126 was isolated and studied. The lipid A fatty acid composition of the investigated LPS was similar to that of other members of the family Enterobacteriaceae. The E. coli 126 LPS was more toxic than the LPSs of previously studied E. coli strains and of other members of the Enterobacteriaceae (Budvicia aquatica and Pragia fontium), and was less pyrogenic than pyrogenal. SDS-PAG electrophoresis showed a bimodal distribution typical of S-form LPSs. The LPS of E. coli 126 decreased the adhesive index indicating a possible competition between LPS molecules of E. coli 126 and adhesins of E. coli F-50 on rabbit erythrocytes. The LPS of E. coli 126 in a homologous system showed antigenic activity in the reactions of double immunodiffusion in agar by Ouchterlony. No serological cross-reaction of the LPS of other E. coli strains, as well as of that of the B. aquatica type strain, with the antiserum to E. coli 126 was observed. The structural components of the lipopolysaccharide obtained by mild acid hydrolysis were lipid A, the core oligosaccharide, and the O-specific polysaccharide. Based on the data of monosaccharide analysis and 1H and 13C NMR spectroscopy it was found that the O-specific polysaccharide had the structure characteristic of the representatives of E. coli serogroup O15.

Lipopolysaccharide, Escherichia coli, O-specific polysaccharide, biological activity

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3	bDGalp	101.5	79.7	75.1	70.5	76.7	62.5
3,2	Ac
3	aLFucpN	99.2	51.2	78.2	70.6	67.2	16.8
2	Ac
	bDGlcpN	103.4	57.1	80.0	70.2	77.7	62.5


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3	bDGalp	4.48	3.63	3.63	3.84	3.62	3.77
3,2	Ac
3	aLFucpN	5.06	4.20	4.06	3.84	4.42	1.26
2	Ac
	bDGlcpN	4.72	3.88	3.66	3.49	3.48	3.73-3.96


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,3	bDGalp	101.5/4.48	79.7/3.63	75.1/3.63	70.5/3.84	76.7/3.62	62.5/3.77
3,2	Ac
3	aLFucpN	99.2/5.06	51.2/4.20	78.2/4.06	70.6/3.84	67.2/4.42	16.8/1.26
2	Ac
	bDGlcpN	103.4/4.72	57.1/3.88	80.0/3.66	70.2/3.49	77.7/3.48	62.5/3.73-3.96

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

552.53 g/mol (C₂₂H₃₆R₂N₂O₁₄, R = next and previous repeats, not counted in mol weight)