An Empirical Study of Amide-Heteroarene pi-Stacking Interactions Using Reversible Inhibitors of a Bacterial Serine Hydrolase.
DeFrees, K., Kemp, M.T., ElHilali-Pollard, X., Zhang, X., Mohamed, A., Chen, Y., Renslo, A.R.(2019) Org Chem Front 6: 1749-1756
- PubMed: 32774871 
- DOI: https://doi.org/10.1039/c9qo00342h
- Primary Citation of Related Structures:  
6OOE, 6OOF, 6OOH, 6OOJ, 6OOK - PubMed Abstract: 
Compared to aryl-aryl π-stacking interactions, the analogous stacking of heteroarenes on amide π systems is less well understood and vastly underutilized in structure-based drug design. Recent theoretical studies have delineated the important geometric coordinates of the interaction, some of which have been confirmed with synthetic model systems based on Rebek imides. Unfortunately, a broadly useful and tractable protein-ligand model system of this interaction has remained elusive. Here we employed a known inhibitor scaffold to study π-stacking of diverse heteroarene substituents on the amide face of Gly238 in the cephalosporinases CTX-M-14 and CTX-M-27. Biochemical inhibition constants ( K i ) and biophysical binding constants ( K d ) were determined for nineteen new analogues against both enzymes, while multiple high-resolution co-crystal structures revealed remarkably consistent placement of the probe heteroarene on Gly238. The data presented support the predicted importance of opposing dipoles in amide-heteroarene interactions and should be useful for evaluating other theoretical predictions concerning these interactions.
Organizational Affiliation: 
Department of Pharmaceutical Chemistry, University of California San Francisco, 600 16th St., San Francisco, California 94158, United States.