Site-specific conjugation to antibody lysine residues with solid-phase immobilized microbial transglutaminase MTG and MTG in solution

Abstract

Site-specific modification of proteins with microbial transglutaminase (MTG) is a powerful and versatile strategy for a controlled modification of proteins under physiological conditions. Solid-phase microbead-immobilization is used to site-specifically and efficiently attach different functional molecules important for further downstream applications to proteins of therapeutic relevance including scFV, Fab-fragment and antibodies. MTG remained firmly immobilized with no detectable column bleeding and enzyme activity was sustained during continuous operation. Immobilized MTG shows enhanced selectivity towards a certain residue in the presence of several reactive residues which are all targeted when the conjugation was carried out in solution. The generation of dual site-specifically conjugated IgG1 with immobilized and MTG in solution is reported, i.e. site-specific conjugation to glutamine and lysine residues of IgG1 antibody. Site-specific glutamine conjugation with small peptides containing a lysine residue and a functional moiety is also described.

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