The diversity of capsular polysaccharides of the bacterial pathogen Streptococcus pneumoniae leads to at least 91 different serotypes. While the genetic loci for capsular biosynthesis have been characterized for all serotypes, the determination of resultant polysaccharide structures remains incomplete. Here, we report the chemical structures of the capsular polysaccharides of serotypes 39, 42, and 47F from the genetic cluster 4, and discuss the structures in the context of structures from serologically and genetically related serotypes. Antigenic determinants can be approximated in this manner. The structure of the serotype 39 capsular polysaccharide is and has identical composition to the capsular polysaccharide 10A, but two different linkages. The serotype 42 structure closely resembles the genetically related serotype 35A, which does not contain residue A. The structure of the serotype 47F capsular polysaccharide is somewhat different from a recently determined structure from the same serogroup, while containing a structural motif that is reflected in serotype 35A and 42 capsular polysaccharide structures, thus explaining the cross-reactivity of serotype 47F with the typing serum 35a.

Streptococcus pneumoniae, capsular polysaccharide, Serotypes, serotype 47F, serotype 39, serotype 42

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
0,2,3,6,3,3	Ac	174.0	20.9
0,2,3,6,3,5	Ac	173.8	20.9
0,2,3,6,3	bDGalf	109.8	79.4	79.4	80.8	71.6	64.1
0,2,3,6	bDGalp	103.6	70.5	80.7	69	75.8	61.5
0,2,3,2	Ac	173.7	20.9
0,2,3	bDGalf	107.6	84.5	76.2	84.4	70.3	71.5
0,2	aDGalp	99.7	68.2	77.7	69.6	71.7	61.5
0	xDRib-ol	60.6	80.3	72.2	71.0	67.5
	P


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
0,2,3,6,3,3	Ac	-	2.143
0,2,3,6,3,5	Ac	-	2.017
0,2,3,6,3	bDGalf	5.299	4.349	4.885	4.484	5.363	4.05-4.05
0,2,3,6	bDGalp	4.497	3.665	3.741	4.074	3.708	3.73-3.73
0,2,3,2	Ac	-	2.134
0,2,3	bDGalf	5.379	5.061	4.228	4.143	4.038	3.779-4.054
0,2	aDGalp	5.237	3.966	4.007	4.161	4.068	3.73-3.769
0	xDRib-ol	3.838-3.916	4.035	4.002	3.84	3.939-4.054
	P


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
0,2,3,6,3,3	Ac		20.9/2.143
0,2,3,6,3,5	Ac		20.9/2.017
0,2,3,6,3	bDGalf	109.8/5.299	79.4/4.349	79.4/4.885	80.8/4.484	71.6/5.363	64.1/4.05-4.05
0,2,3,6	bDGalp	103.6/4.497	70.5/3.665	80.7/3.741	69/4.074	75.8/3.708	61.5/3.73-3.73
0,2,3,2	Ac		20.9/2.134
0,2,3	bDGalf	107.6/5.379	84.5/5.061	76.2/4.228	84.4/4.143	70.3/4.038	71.5/3.779-4.054
0,2	aDGalp	99.7/5.237	68.2/3.966	77.7/4.007	69.6/4.161	71.7/4.068	61.5/3.73-3.769
0	xDRib-ol	60.6/3.838-3.916	80.3/4.035	72.2/4.002	71.0/3.84	67.5/3.939-4.054
	P

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

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

988.785 g/mol (C₃₅H₅₇R₂O₃₀P, R = next and previous repeats, not counted in mol weight)