One Question, Multiple Answers: Biochemical and Biophysical Screening Methods Retrieve Deviating Fragment Hit Lists

Area of Science:

• Biochemistry
• Drug Discovery
• Structural Biology

Background:

• Fragment-based lead discovery (FBLD) is a key strategy in modern drug development.
• Crystallography is crucial for optimizing fragment hits into drug leads, requiring reliable identification of binders.
• Endothiapepsin serves as a model system for studying disease-relevant aspartic proteases.

Purpose of the Study:

• To compare the hit lists generated by various biophysical screening methods in FBLD.
• To assess the concordance between different techniques for identifying protein-fragment binders.
• To evaluate the effectiveness of a comprehensive screening approach.

Main Methods:

• A library of 361 fragments was screened against endothiapepsin.
• Techniques included a biochemical assay, reporter-displacement assay, saturation-transfer difference NMR, native mass spectrometry, thermophoresis, and thermal shift assay.
• Crystal structures were used to validate fragment binding.

Main Results:

• A biochemical assay initially identified 11 potential fragment binders.
• The comprehensive screening approach successfully retrieved 10 of these 11 validated binders.
• Despite overall success, the overlap between hit lists from individual screening methods was surprisingly low.

Conclusions:

• Different biophysical screening techniques provide complementary information in FBLD.
• The choice of screening method impacts the collection of identified fragment hits.
• A multi-technique screening strategy is valuable for robust hit identification in drug discovery.