Fast and Cysteine‐Specific Modification of Peptides, Proteins and Bacteriophage Using Chlorooximes
Fa‐Jie Chen, Mengmeng Zheng, Vincent Nobile, Jianmin Gao
Abstract
Abstract This work reports a novel chlorooxime mediated modification of native peptides and proteins under physiologic conditions. This method features fast reaction kinetics (apparent k 2 =306±4 M −1 s −1 for GSH) and exquisite selectivity for cysteine residues. This cysteine conjugation reaction can be carried out with just single‐digit micromolar concentrations of the labeling reagent. The conjugates show high stability towards acid, base, and external thiol nucleophiles. A nitrile oxide species generated in situ is likely involved as the key intermediate. Furthermore, a bis‐chlorooxime reagent is synthesized to enable facile Cys‐Cys stapling in native peptides and proteins. This highly efficient cysteine conjugation and stapling was further implemented on bacteriophage to construct chemically modified phage libraries.