Immunospecificity of gram-negative bacteria, including Escherichia coli, is defined by the fine structure of the O-specific polysaccharide chain of the lipopolysaccharide called O-antigen. Structures of the O-antigens have been established for the majority of about 200 known serotypes of E. coli but serotype O162 was among few that have not been studied in this respect yet. In the present work, it was found that bacteria of this serotype produce several O-polysaccharides differing in the main chains composed of N-acetylglucosamine and N-acetylgalactosamine residues as well as in the presence or absence of side-chain 4-deoxy-D-arabino-hexose residues. It was also shown that E. coli O101 produces two linear O-polysaccharides, which are structurally similar to the main chains of E. coli O162, whereas only one of them had been identified in these bacteria earlier.

Lipopolysaccharide, structure, O-antigen, Escherichia coli, O-specific polysaccharide, 4-deoxy-D-arabino-hexose

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
4,2	Ac	175.3-176.0	23.1-23.5
4	bDGalpN	104.0	53.7	71.9	76.4	76.5	61.6
2	Ac	175.3-176.0	23.1-23.5
	aDGalpN	99.1	51.5	68.3	77.4	71.4	61.7


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
4,2	Ac	-	2.03-2.09
4	bDGalpN	4.71	4.06	3.83	4.01	3.72	3.67-3.82
2	Ac	-	2.03-2.09
	aDGalpN	4.91	4.14	4.21	4.23	4.41	3.71


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
4,2	Ac		23.1-23.5/2.03-2.09
4	bDGalpN	104.0/4.71	53.7/4.06	71.9/3.83	76.4/4.01	76.5/3.72	61.6/3.67-3.82
2	Ac		23.1-23.5/2.03-2.09
	aDGalpN	99.1/4.91	51.5/4.14	68.3/4.21	77.4/4.23	71.4/4.41	61.7/3.71

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

406.388 g/mol (C₁₆H₂₆R₂N₂O₁₀, R = next and previous repeats, not counted in mol weight)