Condensation of 2-cyanobenzothiazole (CBT) and cysteine yielding luciferin has been applied to selectively label proteins containing N-terminal cysteine. Herein we report a new reaction pathway where CBT reacts with NCys forming an amidine product which allows the side chain thiol for further modification. This non-luciferin pathway is favored under basic conditions and dependent on the peptide sequence downstream of the NCys. Especially, a tripeptide tag CIS which can afford N, S-double labeled product with the excellent yield was discovered. These features would enhance the applicability of CBT-Cys chemistry for site-specific labeling of proteins.

N,S-double labeling of N-terminal cysteines via an alternative pathway of 2-cyanobenzothiazole condensation

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.