A polysaccharide was isolated from the opportunistic human pathogen Providencia alcalifaciens O45:H26 by extraction with aqueous phenol and studied by sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including two-dimensional ROESY and H-detected (1)H,(13)C HSQC experiments. The polysaccharide contains N-acetylglucosamine and N-acetylmuramic acid (D-GlcpNAc3Rlac) amidated with L-alanine and has the following structure:-4)-b-D-GlcpNAc-(1-4)-b-D-GlcpNAc3(Rlac-L-Ala)-(1-. The polysaccharide possesses a remarkable structural similarity to the bacterial cell wall peptidoglycan. It is not unique to the strain studied but is common to strains of at least four P. alcalifaciens O-serogroups (O3, O24, O38, and O45). No evidence was obtained that the polysaccharide is associated with the LPS, and hence it might represent a bacterial capsule component.

Lipopolysaccharide, Providencia alcalifaciens, Bacterial polysaccharide, peptidoglycan, N-acetylmuramic acid

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
4,2	Ac	175.7	23.2
4	bDGlcpN	101.5	56.5	73.3	80.8	75.9	61.5
2	Ac	175.4	23.4
3,1	xLAla?	174.7	50.4	17.4
3	lRLac	178.8	79.3	17.4
	bDGlcpN	102.6	55.8	80.2	76.2	76.2	60.9


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
4,2	Ac	-	2.03
4	bDGlcpN	4.50	3.75	3.68	3.53	3.46	3.68-3.84
2	Ac	-	1.98
3,1	xLAla?	-	4.30	1.43
3	lRLac	-	4.39	1.37
	bDGlcpN	4.52	3.79	3.63	4.85	3.50	3.69-3.87


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
4,2	Ac		23.2/2.03
4	bDGlcpN	101.5/4.50	56.5/3.75	73.3/3.68	80.8/3.53	75.9/3.46	61.5/3.68-3.84
2	Ac		23.4/1.98
3,1	xLAla?		50.4/4.30	17.4/1.43
3	lRLac		79.3/4.39	17.4/1.37
	bDGlcpN	102.6/4.52	55.8/3.79	80.2/3.63	76.2/4.85	76.2/3.50	60.9/3.69-3.87

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](C)C(=O)N[C@@H](C)C(=O)O)[C@H](NC(C)=O)[C@H]1O

549.53 g/mol (C₂₂H₃₅R₂N₃O₁₃, R = next and previous repeats, not counted in mol weight)