Structure and Characterization of a Covalent Inhibitor of Src Kinase.
Gurbani, D., Du, G., Henning, N.J., Rao, S., Bera, A.K., Zhang, T., Gray, N.S., Westover, K.D.(2020) Front Mol Biosci 7: 81-81
- PubMed: 32509799 
- DOI: https://doi.org/10.3389/fmolb.2020.00081
- Primary Citation of Related Structures:  
6E6E - PubMed Abstract: 
Unregulated Src activity promotes malignant processes in cancer, but no Src-directed targeted therapies are used clinically, possibly because early Src inhibitors produce off-target effects leading to toxicity. Improved selective Src inhibitors may enable Src-directed therapies. Previously, we reported an irreversible Src inhibitor, DGY-06-116, based on the hybridization of dasatinib and a promiscuous covalent kinase probe SM1-71. Here, we report biochemical and biophysical characterization of this compound. An x-ray co-crystal structure of DGY-06-116: Src shows a covalent interaction with the kinase p-loop and occupancy of the back hydrophobic kinase pocket, explaining its high potency, and selectivity. However, a reversible analog also shows similar potency. Kinetic analysis shows a slow inactivation rate compared to other clinically approved covalent kinase inhibitors, consistent with a need for p-loop movement prior to covalent bond formation. Overall, these results suggest that a strong reversible interaction is required to allow sufficient time for the covalent reaction to occur. Further optimization of the covalent linker may improve the kinetics of covalent bond formation.
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States.
Organizational Affiliation: