The Wnt signaling suppressor Notum is a promising target for osteoporosis, Alzheimer's disease, and colorectal cancers. To develop novel Notum inhibitors, we used an X-ray crystallographic fragment screen with the Diamond-SGC Poised Library (DSPL) and identified 59 fragment hits from the analysis of 768 data sets. Fifty-eight of the hits were found bound at the enzyme catalytic pocket with potencies ranging from 0.5 to >1000 microM. Analysis of the fragments' diverse binding modes, enzymatic inhibitory activities, and chemical properties led to the selection of six hits for optimization, and five of these resulted in improved Notum inhibitory potencies. One hit, 1-phenyl-1,2,3-triazole 7, and its related cluster members, have shown promising lead-like properties. These became the focus of our fragment development activities, resulting in compound 7d with IC(50) 0.0067 microM. The large number of Notum fragment structures and their initial optimization provided an important basis for further Notum inhibitor development.
        
Representative scheme of Pectinacetylesterase-Notum structure and an image from PDBsum server
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Databases
PDB-Sum
7B7W Previously Class, Architecture, Topology and Homologous superfamily - PDB-Sum server
FSSP
7B7WFold classification based on Structure-Structure alignment of Proteins - FSSP server