Conjugation of α-Ketoacid Saccharides with Proteins Using o-Phenylenediamine Linkers: An Approach to Vaccines against Group B Neisseria meningitidis
Date Issued
2011
Date
2011
Author(s)
Hsu, Peng-Hao
Abstract
Bacterial surface polysaccharides are virulent agents for bacterial infection and often chosen as the target of carbohydrate-based vaccines; however, these polysaccharides need to be conjugated to proteins to elicit T-cell mediated immune response. Among bacterial surface polysaccharides, polysialic acid (PSA) and lipopolysaccharide (LPS) are unique in that their terminal saccharides are α-ketoacids. Although there are many methods for conjugation of glycoproteins, the corresponding conjugation methods for α-ketoacid-based glycoproteins are less common.
We report here a method for conjugation of α-ketoacid saccharides with proteins by using condensation reactions of α-ketoacid with o-phenylenediamine (OPD) and Michael addition of thiol to maleimide (MA). Our results showed that α-ketoacid mono-, di-, and polysaccharides were efficiently condensed with the OPD linker bearing a terminal amino group. These saccharide quinoxalinone derivatives were then modified with a terminal thiol, and the subsequent Michael addition furnished the conjugation of thiol-terminated sialic acid–quinoxalinone derivative to MA-modified bovine serum albumin (MA–BSA). In the case of NPrPSA, a α-ketoacid polysaccharide, its quinoxalinone derivative bearing terminal thiol was prepared, but the subsequent conjugation to MA–BSA failed with unclear reason. The preparation of NPrPSA–BSA conjugate as a vaccine against group B Neisseria meningitidis may be attempted in a different approach.
We report here a method for conjugation of α-ketoacid saccharides with proteins by using condensation reactions of α-ketoacid with o-phenylenediamine (OPD) and Michael addition of thiol to maleimide (MA). Our results showed that α-ketoacid mono-, di-, and polysaccharides were efficiently condensed with the OPD linker bearing a terminal amino group. These saccharide quinoxalinone derivatives were then modified with a terminal thiol, and the subsequent Michael addition furnished the conjugation of thiol-terminated sialic acid–quinoxalinone derivative to MA-modified bovine serum albumin (MA–BSA). In the case of NPrPSA, a α-ketoacid polysaccharide, its quinoxalinone derivative bearing terminal thiol was prepared, but the subsequent conjugation to MA–BSA failed with unclear reason. The preparation of NPrPSA–BSA conjugate as a vaccine against group B Neisseria meningitidis may be attempted in a different approach.
Subjects
α-ketoacid saccharide
o-phenylenediamine
quinoxalinone
glycoprotein
vaccine
group B Neisseria meningitidis
SDGs
Type
thesis
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