New paper in JACS, our first since relocating to NYCU: thiol-retaining N-terminal cysteine chemistry. Continuing our collaboration with Dr. Yu-Hsuan Tsai, we report a strategy that traps N-terminal cysteine’s 1,2-aminothiol as a stable thiol-retaining conjugate instead of the usual cyclic thiazoline, enabling dual-modification and bicyclic peptide construction.Our contribution rationalized this selectivity computationally, showing how steric bulk on the reagent tips the balance away from cyclization — the reasoning behind that, including an interactive figure, is written up here. Our first paper since relocating to NYCU. DOI: 10.1021/jacs.6c01648.