High-molecular-mass polysaccharides were released by mild acid degradation of the lipopolysaccharides of two wild-type Vibrio vulnificus strain, a flagellated motile strain CECT 5198 and a non-flagellated non-motile strain S3-I2-36. Studies by sugar analysis and partial acid hydrolysis along with (1)H and (13)C NMR spectroscopies showed that the polysaccharides from both strains have the same trisaccharide repeating unit of the following structure: →4)-β-D-GlcpNAc3NAcylAN-(1→4)-α-L-GalpNAmA-(1→3)-α-D-QuipNAc-(1→ where QuiNAc stands for 2-acetamido-2,6-dideoxyglucose, GalNAmA for 2-acetimidoylamino-2-deoxygalacturonic acid, GlcNAc3NAcylAN for 2-acetamido-3-acylamino-2,3-dideoxyglucuronamide and acyl for 4-d-malyl (approximately 30%) or 2-O-acetyl-4-d-malyl (approximately 70%). The structure of the polysaccharide studied resembles much that of a marine bacterium Pseudoalteromonas rubra ATCC 29570 reinvestigated in this work. The latter differs in (i) the absolute configuration of malic acid (l vs d), (ii) 3-O-acetylation of GalNAmA and (iii) replacement of QuiNAc with its 4-keto biosynthetic precursor.

Lipopolysaccharide, bacterial polysaccharide structure, 2, 3-diamino-2, Vibrio vulnificus, N-Acetimidoyl-L-galactosaminuronic acid, 3-dideoxy-d-glucuronamide, malic acid

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,4,3	xR2HOSuc	?	70.8	42.8	?
3,4,2	Ac	?	24.0
3,4,6	NH2
3,4	bDGlcpN3NA	102.7	54.6	56.0	71.6	78.8	?
3,2	Am	?	20.3
3	aLGalpNA	96.4-96.6	54.7	68.1	79.9	72.3	?
2	Ac	?	23.4
	aDQuipN	92.2	55.8	75.9	75.4	68.9	18.3


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,4,3	xR2HOSuc	-	4.30	2.44-2.74	-
3,4,2	Ac	-	2.03
3,4,6	NH2
3,4	bDGlcpN3NA	4.68	3.84	4.04	3.62	3.86	-
3,2	Am	?	2.28-2.30
3	aLGalpNA	5.27-5.28	3.95	4.54	5.45	4.74-4.75	-
2	Ac	-	2.00
	aDQuipN	5.01	4.06	3.91	3.23	3.96	1.27


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,4,3	xR2HOSuc		70.8/4.30	42.8/2.44-2.74	
3,4,2	Ac		24.0/2.03
3,4,6	NH2
3,4	bDGlcpN3NA	102.7/4.68	54.6/3.84	56.0/4.04	71.6/3.62	78.8/3.86	
3,2	Am	?/?	20.3/2.28-2.30
3	aLGalpNA	96.4-96.6/5.27-5.28	54.7/3.95	68.1/4.54	79.9/5.45	72.3/4.74-4.75	
2	Ac		23.4/2.00
	aDQuipN	92.2/5.01	55.8/4.06	75.9/3.91	75.4/3.23	68.9/3.96	18.3/1.27

The spectrum also has 7 signals at unknown positions (not plotted).

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

CC(=N)N[C@H]1[C@H](O)[C@H](O[C@@H]2O[C@H](C(N)=O)[C@@H](O)[C@H](NC(=O)C[C@@H](O)C(=O)O)[C@H]2NC(C)=O)[C@H](C(=O)O)O[C@H]1O[C@@H]1[C@@H](NC(C)=O)[C@@H](O)O[C@H](C)[C@H]1O

752.684 g/mol (C₂₈H₄₄N₆O₁₈)