Chloromethyl Acryl Reagents for Simple and Site-Selective Cysteine and Disulfide Modification

The generation of protein biotherapeutics with improved features compared to the synthetic drugs has received emerging interest. The conjugation of various synthetic functionalities to proteins provides access to new classes of protein conjugates, where the advantages from both the synthetic world and Nature can be combined in a synergistic fashion. Here, we reported that 2-chloromethyl acryl scaffold can serve as a simple yet versatile platform for synthesizing acrylamide or acrylate derivatives by coupling with different end-group functionalities (amino group or hydroxyl group) via a one-pot reaction. The chemical properties of the amide or ester linkage influence their inherent reactivity as bioconjugation reagents, which in turn allows synthetic customization of their features to achieve selective protein modification at cysteine or disulfide sites on demand. 2-Chloromethyl acrylamide reagents with amide linkage favors selective modification at cysteine site with high efficiency and the resultant bioconjugates exhibit superior stability compared to commonly employed maleimide-thiol conjugates. In contrast, 2-chloromethyl acrylate reagents bearing ester linkage can undergo two successive Michael reaction, allowing the selective modification of disulfides with high labelling efficiency and conjugate stability. These reagents could outperform widely applied maleimide reagents in terms of stability of the resultant bioconjugates without compromising on the ease of reagent preparation, reactivity and reaction speed.