Sunday, January 30, 2022

Discovery of Non-Cysteine-Targeting Covalent Inhibitors by Activity-Based Proteomic Screening with a Cysteine-Reactive Probe

Yejin Jung, Naotaka Noda, Junichiro Takaya, Masahiro Abo, Kohei Toh, Ken Tajiri, Changyi Cui, Lu Zhou, Shin-ichi Sato, and Motonari Uesugi

ACS Chemical Biology 2021

DOI: 10.1021/acschembio.1c00824

Covalent inhibitors of enzymes are increasingly appreciated as pharmaceutical seeds, yet discovering non-cysteine-targeting inhibitors remains challenging. Herein, we report an intriguing experience during our activity-based proteomic screening of 1601 reactive small molecules, in which we monitored the ability of library molecules to compete with a cysteine-reactive iodoacetamide probe. One epoxide molecule, F8, exhibited unexpected enhancement of the probe reactivity for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a rate-limiting glycolysis enzyme. In-depth mechanistic analysis suggests that F8 forms a covalent adduct with an aspartic acid in the active site to displace NAD+, a cofactor of the enzyme, with concomitant enhancement of the probe reaction with the catalytic cysteine. The mechanistic underpinning permitted the identification of an optimized aspartate-reactive GAPDH inhibitor. Our findings exemplify that activity-based proteomic screening with a cysteine-reactive probe can be used for discovering covalent inhibitors that react with non-cysteine residues.



Identification of a cell-active chikungunya virus nsP2 protease inhibitor using a covalent fragment-based screening approach

Eric M. Merten  and John D. Sears  and Tina M. Leisner  and P. Brian Hardy  and Anirban Ghoshal  and Mohammad Anwar Hossain  and Kesatebrhan...