Selective Protein (Post-)modifications through Dynamic Covalent Chemistry: Self-activated S_NAr Reactions

Area of Science:

• Organic Chemistry
• Bioconjugation Chemistry
• Chemical Biology

Background:

• Nucleophilic aromatic substitution (S_NAr) reactions are crucial for molecular functionalization.
• Achieving high yields and selectivity in bioconjugation remains a challenge.
• Dynamic covalent chemistry (DCvC) offers versatile tools for molecular assembly and modification.

Purpose of the Study:

• To develop a novel pretargeting and activating unit for accelerating S_NAr reactions.
• To investigate the self-activation mechanism of salicylaldehyde derivatives via iminium formation.
• To apply this strategy for selective antibody functionalization and post-modification.

Main Methods:

• Utilized dynamic covalent chemistry (DCvC) to create a pretargeting and activating unit.
• Investigated S_NAr reactions on salicylaldehyde derivatives with model peptides.
• Applied the developed strategy for the functionalization of IgG1 and IgG4 antibodies.
• Performed post-functionalization via dynamic covalent exchange with hydrazides.

Main Results:

• Remarkable acceleration of S_NAr reactions was achieved through iminium formation.
• Self-activation of salicylaldehyde derivatives by neighboring lysine residues enhanced reaction rates.
• Increased bioconjugation yields and excellent chemo-selectivity were observed in antibody functionalization.
• Microenvironment selectivity was achieved with IgG4 antibodies due to fewer lysine residues in the hinge region.
• Successful post-functionalization of modified antibodies was demonstrated.

Conclusions:

• DCvC-based pretargeting and activation units significantly enhance S_NAr bioconjugation.
• The iminium bond formation provides a self-activation mechanism, improving reaction efficiency.
• This strategy enables selective antibody functionalization with tunable product distributions.
• The developed
• tag and modify
• approach represents a powerful new tool for bioconjugation.