Direct Conjugation of Bacterial Polysaccharides to Proteins by Squaric Acid Chemistry

  • Peng Xu
  • Pavol KováčEmail author
Part of the Methods in Molecular Biology book series (MIMB, volume 1954)


Bacterial polysaccharides that contain one amino group can be conjugated using squaric acid chemistry directly to a protein carrier. The conjugation is a two-step process consisting of labeling the polysaccharide with a squarate group and a reaction of the squarate formed with protein. The intermediate squarate derivative and the product glycoconjugate can be easily purified using centrifugal filtration devices. This method is experimentally simple and affords glycoconjugates with predictable carbohydrate–protein ratio (carbohydrate content), high conjugation efficiency, and excellent yield.

Key words

Bacterial polysaccharides O antigens O-specific polysaccharides Squaric acid chemistry Conjugation Glycoconjugate 


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Laboratory of Bioorganic ChemistryNational Institutes of HealthBethesdaUSA

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