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Biochemistry. 2017 Jun 27;56(25):3178-3183. doi: 10.1021/acs.biochem.7b00271. Epub 2017 Jun 16.

Expanding the Scope of Electrophiles Capable of Targeting K-Ras Oncogenes.

Author information

1
Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco , San Francisco, California 94158, United States.
2
Department of Biochemistry and Microbiology, University of Victoria , Victoria, BC V8W 2Y2, Canada.

Abstract

There is growing interest in reversible and irreversible covalent inhibitors that target noncatalytic amino acids in target proteins. With a goal of targeting oncogenic K-Ras variants (e.g., G12D) by expanding the types of amino acids that can be targeted by covalent inhibitors, we survey a set of electrophiles for their ability to label carboxylates. We functionalized an optimized ligand for the K-Ras switch II pocket with a set of electrophiles previously reported to react with carboxylates and characterized the ability of these compounds to react with model nucleophiles and oncogenic K-Ras proteins. Here, we report that aziridines and stabilized diazo groups preferentially react with free carboxylates over thiols. Although we did not identify a warhead that potently labels K-Ras G12D, we were able to study the interactions of many electrophiles with K-Ras, as most of the electrophiles rapidly label K-Ras G12C. We characterized the resulting complexes by crystallography, hydrogen/deuterium exchange, and differential scanning fluorimetry. Our results both demonstrate the ability of a noncatalytic cysteine to react with a diverse set of electrophiles and emphasize the importance of proper spatial arrangements between a covalent inhibitor and its intended nucleophile. We hope that these results can expand the range of electrophiles and nucleophiles of use in covalent protein modulation.

PMID:
28621541
PMCID:
PMC5665167
DOI:
10.1021/acs.biochem.7b00271
[Indexed for MEDLINE]
Free PMC Article

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