SuFEx-enabled, agnostic discovery of covalent inhibitors of human neutrophil elastase

Qinheng Zheng, Jordan L. Woehl, Seiya Kitamura, Diogo Santos-Martins, Christopher J. Smedley, Gencheng Li, Stefano Forli, John E. Moses, Dennis W. Wolan, and K. Barry Sharpless

PNAS,  2019 116 (38) 18808-18814
doi: 10.1073/pnas.1909972116

Sulfur fluoride exchange (SuFEx) has emerged as the new generation of click chemistry. We report here a SuFEx-enabled, agnostic approach for the discovery and optimization of covalent inhibitors of human neutrophil elastase (hNE). Evaluation of our ever-growing collection of SuFExable compounds toward various biological assays unexpectedly revealed a selective and covalent hNE inhibitor: benzene-1,2-disulfonyl fluoride. Synthetic derivatization of the initial hit led to a more potent agent, 2-(fluorosulfonyl)phenyl fluorosulfate with IC50 0.24 μM and greater than 833-fold selectivity over the homologous neutrophil serine protease, cathepsin G. The optimized, yet simple benzenoid probe only modified active hNE and not its denatured form.