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Automated glycan assembly of a S. pneumoniae serotype 3 CPS antigen

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ABSTRACT

Vaccines against S. pneumoniae, one of the most prevalent bacterial infections causing severe disease, rely on isolated capsular polysaccharide (CPS) that are conjugated to proteins. Such isolates contain a heterogeneous oligosaccharide mixture of different chain lengths and frame shifts. Access to defined synthetic S. pneumoniae CPS structures is desirable. Known syntheses of S. pneumoniae serotype 3 CPS rely on a time-consuming and low-yielding late-stage oxidation step, or use disaccharide building blocks which limits variability. Herein, we report the first iterative automated glycan assembly (AGA) of a conjugation-ready S. pneumoniae serotype 3 CPS trisaccharide. This oligosaccharide was assembled using a novel glucuronic acid building block to circumvent the need for a late-stage oxidation. The introduction of a washing step with the activator prior to each glycosylation cycle greatly increased the yields by neutralizing any residual base from deprotection steps in the synthetic cycle. This process improvement is applicable to AGA of many other oligosaccharides.

No MeSH data available.


Related in: MedlinePlus

HPLC chromatogram of the crude products of the automated solid-phase SP3 trisaccharide 5 synthesis; conditions: YMC Diol 300, H/EtOAc, 0% EtOAc (5 min) to 60% EtOAc (60 min), 254 nm.
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Figure 5: HPLC chromatogram of the crude products of the automated solid-phase SP3 trisaccharide 5 synthesis; conditions: YMC Diol 300, H/EtOAc, 0% EtOAc (5 min) to 60% EtOAc (60 min), 254 nm.

Mentions: The desired trisaccharide 5 was observed as the main product from the automated synthesis by HPLC analysis (Fig. 5). The Lev protecting group had been removed quantitatively while no benzoyl ester cleavage was observed. None of the byproducts could be identified by either ESIMS or NMR.


Automated glycan assembly of a S. pneumoniae serotype 3 CPS antigen
HPLC chromatogram of the crude products of the automated solid-phase SP3 trisaccharide 5 synthesis; conditions: YMC Diol 300, H/EtOAc, 0% EtOAc (5 min) to 60% EtOAc (60 min), 254 nm.
© Copyright Policy - Beilstein
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4979738&req=5

Figure 5: HPLC chromatogram of the crude products of the automated solid-phase SP3 trisaccharide 5 synthesis; conditions: YMC Diol 300, H/EtOAc, 0% EtOAc (5 min) to 60% EtOAc (60 min), 254 nm.
Mentions: The desired trisaccharide 5 was observed as the main product from the automated synthesis by HPLC analysis (Fig. 5). The Lev protecting group had been removed quantitatively while no benzoyl ester cleavage was observed. None of the byproducts could be identified by either ESIMS or NMR.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Vaccines against S. pneumoniae, one of the most prevalent bacterial infections causing severe disease, rely on isolated capsular polysaccharide (CPS) that are conjugated to proteins. Such isolates contain a heterogeneous oligosaccharide mixture of different chain lengths and frame shifts. Access to defined synthetic S. pneumoniae CPS structures is desirable. Known syntheses of S. pneumoniae serotype 3 CPS rely on a time-consuming and low-yielding late-stage oxidation step, or use disaccharide building blocks which limits variability. Herein, we report the first iterative automated glycan assembly (AGA) of a conjugation-ready S. pneumoniae serotype 3 CPS trisaccharide. This oligosaccharide was assembled using a novel glucuronic acid building block to circumvent the need for a late-stage oxidation. The introduction of a washing step with the activator prior to each glycosylation cycle greatly increased the yields by neutralizing any residual base from deprotection steps in the synthetic cycle. This process improvement is applicable to AGA of many other oligosaccharides.

No MeSH data available.


Related in: MedlinePlus