The antigenic O-polysaccharide moiety of the lipopolysaccharide produced by Escherichia coli serotype O65 was investigated by composition, methylation, base hydrolysis, periodate oxidation, mass spectrometric methods, and by 1D and 2D NMR spectroscopy. The O-polysaccharide had [a]D108° (water) and is a high-molecular-weight unbranched linear polymer of repeating pentasaccharide units composed of 1:1:1:1:1 D-galacturonic acid (D-GalA), D-galacturonamide (D-GalANH2), 2-acetamido-2-deoxy-D-glucose (D-GlcNAc), 2-acetamido-2-deoxy-D-galactose (DGalNAc),and 3-acetamido-3,6-dideoxy-D-glucose (D-Qui3NAc), and has the following structure: [see formula in text]

Lipopolysaccharide, Escherichia coli, NMR spectroscopy, polysaccharide structure

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,4,4,4,3	Ac
3,4,4,4	bDQuip3N	103.76	73.73	56.44	73.72	73.73	17.55
3,4,4,6	NH2
3,4,4	aDGalpA	100.71	69.62	70.38	77.20	71.55	174.40
3,4,2	Ac
3,4	aDGalpN	99.24	50.55	67.28	77.67	71.88	60.27
3	bDGalpA	104.43	70.67	72.47	77.86	74.22	171.48
2	Ac
	aDGlcpN	95.52	52.43	83.21	69.14	73.22	61.42


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,4,4,4,3	Ac
3,4,4,4	bDQuip3N	4.850	3.409	3.869	3.183	3.438	1.269
3,4,4,6	NH2
3,4,4	aDGalpA	5.083	3.767	4.081	4.508	4.802	-
3,4,2	Ac
3,4	aDGalpN	4.990	4.180	4.040	4.150	4.395	3.822-3.842
3	bDGalpA	4.431	3.579	3.825	4.410	4.460	-
2	Ac
	aDGlcpN	5.724	4.111	3.618	3.620	3.620	3.851-3.920


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,4,4,4,3	Ac
3,4,4,4	bDQuip3N	103.76/4.850	73.73/3.409	56.44/3.869	73.72/3.183	73.73/3.438	17.55/1.269
3,4,4,6	NH2
3,4,4	aDGalpA	100.71/5.083	69.62/3.767	70.38/4.081	77.20/4.508	71.55/4.802	
3,4,2	Ac
3,4	aDGalpN	99.24/4.990	50.55/4.180	67.28/4.040	77.67/4.150	71.88/4.395	60.27/3.822-3.842
3	bDGalpA	104.43/4.431	70.67/3.579	72.47/3.825	77.86/4.410	74.22/4.460	
2	Ac
	aDGlcpN	95.52/5.724	52.43/4.111	83.21/3.618	69.14/3.620	73.22/3.620	61.42/3.851-3.920

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

944.847 g/mol (C₃₆H₅₆R₂N₄O₂₅, R = next and previous repeats, not counted in mol weight)

The antigenic O-polysaccharide moiety of the lipopolysaccharide produced by Escherichia coli serotype O65 was investigated by composition, methylation, base hydrolysis, periodate oxidation, mass spectrometric methods, and by 1D and 2D NMR spectroscopy. The O-polysaccharide had [a]D108° (water) and is a high-molecular-weight unbranched linear polymer of repeating pentasaccharide units composed of 1:1:1:1:1 D-galacturonic acid (D-GalA), D-galacturonamide (D-GalANH2), 2-acetamido-2-deoxy-D-glucose (D-GlcNAc), 2-acetamido-2-deoxy-D-galactose (DGalNAc),and 3-acetamido-3,6-dideoxy-D-glucose (D-Qui3NAc), and has the following structure: [see formula in text]

Lipopolysaccharide, Escherichia coli, NMR spectroscopy, polysaccharide structure

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

CC(=O)N[C@@H]([C@H](O)[C@@H](C)O)[C@H](CO)O[C@H]1O[C@H](CO)[C@@H](O)[C@H](O[C@@H]2O[C@H](C(=O)O)[C@H](O[C@H]3O[C@H](CO)[C@H](O[C@H]4OC(C(=O)O)=C[C@H](O)[C@H]4O)[C@H](O)[C@H]3NC(C)=O)[C@H](O)[C@H]2O)[C@H]1NC(C)=O

947.847 g/mol (C₃₆H₅₇N₃O₂₆)

Klebsiella K23 capsular polysaccharide has been investigated by the techniques of hydrolysis, methylation, Smith degradation-periodate oxidation, and base-catalysed degradation, either on the original or the carboxyl-reduced polysaccharide. The structure was found to consist of a tetrasaccharide repeating-unit, as shown below. The anomeric configurations of the sugar residues were determined by 1H-and 13C-n.m.r. spectroscopy on the original and degraded polysaccharides [structure: see text].

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

646.548 g/mol (C₂₄H₃₈R₂O₂₀, R = next and previous repeats, not counted in mol weight)