Capsular Saccharide Glycoconjugates With Click-Chemistry Conjugation
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Solution Overview
Problem
Existing methods for generating glycoconjugates, particularly those involving Streptococcus pneumoniae serotypes 35B and 29 polysaccharides, face challenges such as low yield and high free saccharide due to cleavage during activation, and there is a need for improved conjugation processes that preserve functionality and stability.
Innovation Solution
A method involving reacting capsular saccharides with a carbonic acid derivative and an azido linker in an aprotic solvent, followed by Cu+1 mediated azide-alkyne cycloaddition with an alkyne-functionalized carrier protein, and capping unreacted groups to form stable glycoconjugates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cross-linking or coupling reagents are used to generate glycoconjugates, then conjugation can be achieved, but free reactive sites remain that can react with unwanted molecules in vitro or in vivo, potentially affecting functionality, stability, or causing adverse events
Solution Approach 1:
The patent removes harmful reactive sites from the conjugation process by using copper-catalyzed azide-alkyne cycloaddition, which creates stable triazole linkages without leaving excess reactive groups. The method specifically extracts the problem of free reactive sites by choosing a coupling chemistry (click chemistry) that inherently produces stable, non-reactive conjugates.
Solution Approach 2:
The patent converts the potential harm of reactive sites into a benefit by using azide and alkyne functional groups that are inert under physiological conditions but can be selectively coupled through copper-catalyzed cycloaddition. The resulting triazole linkage is stable and non-reactive, turning what could have been harmful reactive sites into stable conjugation bonds.
2Ease of manufacture
If periodate oxidation is used to activate Streptococcus pneumoniae serotypes 35B and 29 polysaccharides for conjugation, then conjugation can proceed, but the polysaccharides undergo cleavage resulting in low yield and high free saccharide
Solution Approach 1:
The patent changes the chemical parameters of the activation process by replacing periodate oxidation with alternative activation methods such as N-hydroxysuccinimide ester formation or other copper-catalyzed click chemistry approaches. This parameter change avoids the cleavage issue inherent to periodate oxidation while maintaining conjugation efficiency.
Solution Approach 2:
The patent introduces copper catalyst as an intermediary that enables selective coupling of azide-functionalized polysaccharides with alkyne-functionalized carriers without requiring periodate oxidation. This intermediary approach allows conjugation to proceed through a different mechanism that preserves polysaccharide integrity and increases yield.
3Reliability
If excess reactive sites are capped to inactivate them, then safety and stability improve, but the capping reactions may be disruptive to the functionality of the conjugates
Solution Approach 1:
The patent eliminates the need for capping reactions by using click chemistry that inherently produces stable, non-reactive triazole linkages. The method converts the potential harm of reactive sites into a benefit by designing a conjugation system where the coupling reaction itself creates stable bonds without leaving excess reactive groups that would require capping.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method allows for the production of glycoconjugates with very low free saccharide and high yield, effectively addressing the challenges posed by Streptococcus pneumoniae serotypes 35B and 29 polysaccharides.
Implementation Method 1
reacting an isolated capsular saccharide with a carbonic acid derivative and an azido linker in an aprotic solvent to produce an activated azido saccharide
Implementation Method 2
reacting a carrier protein with an agent bearing an N-Hydroxysuccinimide (NHS) moiety and an alkyne group where the NHS moiety reacts with the amino groups to form an amide linkage
Implementation Method 3
reacting the activated azido saccharide of step (a) with the activated alkyne-carrier protein of step (b) by Cu+1 mediated azide-alkyne cycloaddition reaction to form a glycoconjugate
Data Source
AI summary
The present invention relates to new conjugated capsular saccharide antigens (glycoconjugates), immunogenic compositions comprising said glycoconjugates and uses thereof.