Structural Basis for Isoform Selective Nitric Oxide Synthase Inhibition by Thiophene-2-Carboximidamides
Abstract
The over production of nitric oxide in the brain by neuronal nitric oxide synthase (nNOS) is associated with a number of neurodegenerative diseases. Although inhibiting nNOS is an important therapeutic goal, it is important not to inhibit endothelial NOS (eNOS) owing to the critical role played by eNOS in maintaining vascular tone. While it has been possible to develop nNOS selective aminopyridine inhibitors, many of the most potent and selective inhibitors exhibit poor bioavailability properties. Our group and others have turned to more biocompatible thiophene-2-carboximidamides (T2C) inhibitors as potential nNOS selective inhibitors. We have used crystallography and computational methods to better understand how and why 2 commercially developed T2C inhibitors exhibit selectivity for human nNOS over human eNOS. As with many of the aminopyridine inhibitors, a critical active site Asp residue in nNOS vs Asn in eNOS is largely responsible for controlling selectivity. We also present thermodynamic integration results to better understand the change in pKa and thus charge of inhibitors once bound to the active site. In addition, relative free energy calculations underscore the importance of enhanced electrostatic stabilization of inhibitors bound to the nNOS active site compared to eNOS.
Additional Information
© 2018 American Chemical Society. Received: August 27, 2018; Revised: October 8, 2018; Published: October 17, 2018. Accession Codes: Coordinates and structure factors have been deposited in the Protein Data Bank as entries 6CIC, 6CID, 6CIE, and 6CIF. This work was supported by National Institutes of Health Grants GM57353 (T.L.P.) and GM049725 (R.B.S.). The authors declare no competing financial interest. The authors thank the Stanford Synchrotron Radiation Lab and the Advanced Light Source beamline staff for their support during remote X-ray diffraction data collection. The authors also acknowledge the San Diego Supercomputer Center.Attached Files
Accepted Version - nihms-996937.pdf
Supplemental Material - bi8b00895_si_001.pdf
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Additional details
- PMCID
- PMC6282162
- Eprint ID
- 90349
- DOI
- 10.1021/acs.biochem.8b00895
- Resolver ID
- CaltechAUTHORS:20181023-091340888
- GM57353
- NIH
- GM049725
- NIH
- Created
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2018-10-23Created from EPrint's datestamp field
- Updated
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2022-02-17Created from EPrint's last_modified field