Bioconjugation via Hetero‐Selective Clamping of Two Different Amines withortho‐Phthalaldehyde

Abstract

Amino groups are common in both natural and synthetic compounds and offer a very attractive class of endogenous handles for bioconjugation. However, the ability to differentiate two types of amino groups and join them with high hetero‐selectivity and efficiency in a complex setting remains elusive. Herein, we report a new method for bioconjugation via one‐pot chemoselective clamping of two different amine nucleophiles using a simple ortho‐phthalaldehyde (OPA) reagent. Various α‐amino acids, aryl amines, and secondary amines can be crosslinked to the ϵ‐amino side chain of lysine on peptides or proteins with high efficiency and hetero‐selectivity. This method offers a simple and powerful means to crosslink small molecule drugs, imaging probes, peptides, proteins, carbohydrates, and even virus particles without any pre‐functionalization.

Site-Selective Arylation of Carboxamides from Unprotected Peptides

“…However, the anchoring sites for native peptide labeling and stapling are mainly dominated by reactive Cys 52 and Lys. 53,54 The excellent functional group tolerance and synthetic robustness of our strategy for amide modification enable an attractive anchoring site to construct novel labeled peptides and stapled peptides. As a proof of concept, we first labeled the peptide drug nafarelin with the derivative of biotin, which is extensively used for chemoproteomic profiling and drug target discovery.…”

Chemical technology principles for selective bioconjugation of proteins and antibodies

“…73 The involvement of two amines renders 1-aminoisoindole ( 23b ). 74 The latter has propensity to tautomerize and generate isoindolin-1-imine ( 23b-I ) that can further hydrolyze to result in isoindolin-1-one. Along the same lines, a Cys placed in proximity of Lys-derived imine can result in an isoindole derivative ( 23b ) in a mechanistically similar process.…”

Disintegrate (DIN) Theory Enabling Precision Engineering of Proteins

“…Often, this leads to a distinct bioconjugation site. The selection of o -phthalaldehyde can also render stable adducts with external amines . However, it is accompanied by competing pathways that create roadblocks for chemoselectivity and site selectivity.…”

“…The selection of o- phthalaldehyde can also render stable adducts with external amines. 82 However, it is accompanied by competing pathways that create roadblocks for chemoselectivity and site selectivity. On the other hand, the latent electrophilic imine-based intermediates (9b) can be captured site-selectively by the Cu−acetylide complex (11b).…”