The capsular polysaccharide (CPS) of Streptococcus suis serotype 14 was purified, chemically modified, and characterized. Sugar and absolute configuration analyses gave the following CPS composition: D-Gal, 3; D-Glc, 1; D-GlcNAc, 1; D-Neu5Ac, 1. The Sambucus nigra lectin, which recognizes the Neu5Ac(α2-6)Gal/GalNAc sequence, showed binding to the native CPS. Sialic acid was found to be terminal, and the CPS was quantitatively desialylated by mild acid hydrolysis. It was also submitted to periodate oxidation followed by borohydride reduction and Smith degradation. Sugar and methylation analyses, (1)H and (13)C nuclear magnetic resonance, and mass spectrometry of the native CPS or of its specifically modified products allowed to determine the repeating unit sequence: [6)[Neu5Ac(α2-6)Gal(β1-4)GlcNAc(β1-3)]Gal(β1-3)Gal(β1-4)Glc(β1 -](n). S. suis serotype 14 CPS has an identical sialic acid-containing side chain as serotype 2 CPS, but differs by the absence of rhamnose in its composition. The same side chain is also present in group B Streptococcus type Ia CPS, except that in the latter sialic acid is 2,3- rather than 2,6-linked to the following galactose. A correlation between the S. suis CPS sequence and genes of the serotype 14 cps locus encoding putative glycosyltransferases and polymerase responsible for the biosynthesis of the repeating unit is proposed.

chemical modification, nuclear magnetic resonance (NMR), mass spectrometry (MS), repeating unit sequence, Streptococcus suis serotype 14

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
4,3,3,4	bDGalp	105.63	73.73	75.39	71.32	78.02	63.65
4,3,3,2	Ac	177.45	24.96
4,3,3	bDGlcpN	105.18	58.08	74.93	81.48	77.36	62.95
4,3	bDGalp	106.76	72.89	84.48	71.06	75.99	71.62
4	bDGalp	105.31	72.87	84.70	71.06	77.66	63.67
	bDGlcp	105.31	75.56	77.18	81.36	77.49	63.06


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
4,3,3,4	bDGalp	4.48	3.55	3.66	3.93	3.72	3.77
4,3,3,2	Ac	-	2.03
4,3,3	bDGlcpN	4.75	3.77	3.76	3.71	3.59	3.83-3.96
4,3	bDGalp	4.62	3.67	3.73	4.14	3.86	3.89-4.02
4	bDGalp	4.50	3.71	3.81	4.18	3.73	3.77-3.79
	bDGlcp	4.50	3.33	3.64	3.64	3.59	3.80-3.98


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
4,3,3,4	bDGalp	105.63/4.48	73.73/3.55	75.39/3.66	71.32/3.93	78.02/3.72	63.65/3.77
4,3,3,2	Ac		24.96/2.03
4,3,3	bDGlcpN	105.18/4.75	58.08/3.77	74.93/3.76	81.48/3.71	77.36/3.59	62.95/3.83-3.96
4,3	bDGalp	106.76/4.62	72.89/3.67	84.48/3.73	71.06/4.14	75.99/3.86	71.62/3.89-4.02
4	bDGalp	105.31/4.50	72.87/3.71	84.70/3.81	71.06/4.18	77.66/3.73	63.67/3.77-3.79
	bDGlcp	105.31/4.50	75.56/3.33	77.18/3.64	81.36/3.64	77.49/3.59	63.06/3.80-3.98

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

851.758 g/mol (C₃₂H₅₃R₂NO₂₅, R = next and previous repeats, not counted in mol weight)