A Reagent for Amine‐Directed Conjugation to IgG1 Antibodies

Functionalized antibodies are an indispensable resource for diagnosis, therapy and as a research tool for chemical biology. However, simpler and better methodologies are often required to improve the labeling of antibodies in terms of selectivity and scalability. Herein, we report the development of...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2021-03, Vol.60 (12), p.6539-6544
Main Authors: Märcher, Anders, Palmfeldt, Johan, Nisavic, Marija, Gothelf, Kurt V.
Format: Article
Language:English
Subjects:
Antibodies
Antigens
Conjugation
Flow cytometry
fluorophore
IgG1
Immunoglobulin G
Interferometry
Labeling
Lysine
Reagents
Residues
Selectivity
site-direction
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Summary:Functionalized antibodies are an indispensable resource for diagnosis, therapy and as a research tool for chemical biology. However, simpler and better methodologies are often required to improve the labeling of antibodies in terms of selectivity and scalability. Herein, we report the development of an easily available chemical reagent that allows site‐directed labeling of native human IgG1 antibodies in good yield and mono‐labeling selectivity. The salicylaldehyde moiety of the reagent reacts with surface exposed lysine residues to transiently form an iminium ion, and this positions a semi‐reactive ester in proximity of a second lysine residue that reacts with the ester to form an amide. Interestingly, it appears that the formation of the iminium ion also has a significant activating effect of the ester. We use flow cytometry and bio‐layer interferometry to confirm that the labeled antibodies retain antigen binding. A method for site‐directed conjugation to antibodies is developed, in which a first lysine both directs and activates the reagent for reaction with a neighboring lysine.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202013911