Structural Analysis and Development of Notum Fragment Screening Hits.

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Structural Biology

Background:

• Notum is a key suppressor of Wnt signaling, implicated in osteoporosis, Alzheimer's disease, and colorectal cancers.
• Developing specific Notum inhibitors is crucial for therapeutic intervention in these diseases.

Purpose of the Study:

• To discover and optimize novel small-molecule inhibitors of Notum using fragment-based drug discovery.
• To characterize the binding modes and inhibitory potencies of identified fragments.

Main Methods:

• X-ray crystallography was employed for fragment screening using the Diamond-SGC Poised Library (DSPL).
• 768 data sets were analyzed to identify fragment hits binding to the Notum catalytic pocket.
• Hit optimization involved structure-activity relationship studies and chemical modifications.

Main Results:

• 59 fragment hits were identified, with 58 binding to the enzyme's catalytic pocket.
• Fragment potencies ranged from 0.5 to >1000 microM, with six selected for optimization.
• Optimization led to compound 7d, exhibiting a potent IC50 of 0.0067 microM and promising lead-like properties.

Conclusions:

• Fragment-based screening is an effective strategy for identifying Notum inhibitors.
• The identified fragment series, particularly compound 7d, provides a strong foundation for further development of Notum-targeted therapeutics.
• Structural insights from fragment binding aid in rational drug design for Notum inhibitors.