Lipopolysaccharide was extracted from cells of Citrobacter freundii PCM 1443 from serogroup O39 and degraded by mild acid hydrolysis to give an O-polysaccharide. Based on enzymatic and methylation analyses, along with 1H and 13C nuclear magnetic resonance spectroscopy, it was found that the lipopolysaccharide studied has two different linear polysaccharide chains of d-galactan type containing 3-substituted galactose residues. One of the galactans has the disaccharide repeating units of α-D-galactopyranose and β-D-galactofuranose and the other is comprised of α-D-galactopyranose and β-D-galactopyranose, the latter being substituted in 25% repeats with PEtN at O-6. An immunoblotting assay demonstrated that the lipopolysaccharide of C. freundii PCM 1443 is serologically related to that of Klebsiella pneumoniae O1, which contains the same galactan chains but is devoid of phosphoethanolamine.

Lipopolysaccharide, serological specificity, Citrobacter freundii, Galactan, O-Polysaccharide structure

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,6,0	25%xXEtN	63.3	41.4
3,6	P
3	bDGalp	105.6	71.0	78.4	66.1	76.2	62.5
	aDGalp	96.5	68.7	80.5	70.5	71.9	62.3


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,6,0	25%xXEtN	4.11	3.28
3,6	P
3	bDGalp	4.68	3.70-3.77	3.78-3.82	4.19	3.68	3.70-3.80
	aDGalp	5.18	4.02-4.06	4.14	4.29	4.23	3.70-3.80


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,6,0	25%xXEtN	63.3/4.11	41.4/3.28
3,6	P
3	bDGalp	105.6/4.68	71.0/3.70-3.77	78.4/3.78-3.82	66.1/4.19	76.2/3.68	62.5/3.70-3.80
	aDGalp	96.5/5.18	68.7/4.02-4.06	80.5/4.14	70.5/4.29	71.9/4.23	62.3/3.70-3.80

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

447.33 g/mol (C₁₄H₂₆R₂NO₁₃P, R = next and previous repeats, not counted in mol weight)