Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Human cytidine deaminase (CDA) is an enzyme prominent for its role in catalyzing metabolic processing of nucleoside-type anticancer and antiviral agents. It is thus a promising target for the development of small molecule therapeutic adjuvants. We report the first crystal structure of human CDA as a complex with a tight-binding inhibitor, diazepinone riboside 1. The structure reveals that inhibitor 1 is able to establish a canonical pi/pi-interaction with a key active site residue, Phe 137.