Lipopolysaccharide of Proteus penneri strain 63 was degraded by mild acid to give a high molecular mass O-specific polysaccharide that was isolated by gel-permeation chromatography. Sugar and methylation analyses and NMR spectroscopic studies, including two-dimensional 1H, 1H COSY, TOCSY rotating-frame NOE spectroscopy, H-detected 1H,13C and 1H,31P heteronuclear multiple-quantum coherence (HMQC), and 1H, 13C HMQC-TOCSY experiments, demonstrated the following structure of the polysaccharide: where FucNAc is 2-acetamido-2,6-dideoxygalactose and PEtn is 2-aminoethyl phosphate. The polysaccharide studied shares some structural features, such as the presence of D-GlcNAc6PEtn and an α-L-FucNAc-(1→3)-D-GlcNAc disaccharide, with other Proteus O-specific polysaccharides. A marked cross-reactivity of P. penneri 63 O-antiserum with P. vulgaris O12 was observed and substantiated by a structural similarity of the O-specific polysaccharides of the two strains. In spite of this, the polysaccharide of P. penneri 63 has the unique structure among Proteus O-antigens, and therefore a new, separate serogroup, O68, is proposed for this strain.

Lipopolysaccharide, O-antigen, Proteus penneri, 2-aminoethyl phosphate, O-serogroup

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
2,3,3,2	Ac
2,3,3	aDGlcpN	99.0	54.5	72.4	70.5	72.2	69.4
2,3,2	Ac
2,3,4	bDGlcp	104.2	75.0	77.5	70.9	76.8	61.9
2,3	aLFucpN	98.6	50.4	71.4	79.1	68.9	16.7
2,2	Ac
2,6,0	xXEtN	63.2	41.3
2,6	P
2	bDGlcpN	102.2	57.0	78.9	69.5	75.9	66.0
	bDGlcp	103.0	81.2	77.4	70.8	76.8	61.6


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
2,3,3,2	Ac
2,3,3	aDGlcpN	5.05	3.98	3.73	3.72	3.95	4.06
2,3,2	Ac
2,3,4	bDGlcp	4.63	3.45	3.53	3.45	3.42	3.76-3.97
2,3	aLFucpN	5.00	4.46	4.10	4.08	4.47	1.31
2,2	Ac
2,6,0	xXEtN	4.17	3.32
2,6	P
2	bDGlcpN	4.91	3.91	3.77	3.61	3.62	4.13-4.25
	bDGlcp	4.55	3.55	3.55	3.42	3.44	3.73-3.91


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
2,3,3,2	Ac
2,3,3	aDGlcpN	99.0/5.05	54.5/3.98	72.4/3.73	70.5/3.72	72.2/3.95	69.4/4.06
2,3,2	Ac
2,3,4	bDGlcp	104.2/4.63	75.0/3.45	77.5/3.53	70.9/3.45	76.8/3.42	61.9/3.76-3.97
2,3	aLFucpN	98.6/5.00	50.4/4.46	71.4/4.10	79.1/4.08	68.9/4.47	16.7/1.31
2,2	Ac
2,6,0	xXEtN	63.2/4.17	41.3/3.32
2,6	P
2	bDGlcpN	102.2/4.91	57.0/3.91	78.9/3.77	69.5/3.61	75.9/3.62	66.0/4.13-4.25
	bDGlcp	103.0/4.55	81.2/3.55	77.4/3.55	70.8/3.42	76.8/3.44	61.6/3.73-3.91

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

1040.913 g/mol (C₃₈H₆₅R₂N₄O₂₇P, R = next and previous repeats, not counted in mol weight)