Efficient Ligand Discovery Using Sulfur(VI) Fluoride Reactive Fragments.

Area of Science:

• Chemical Biology
• Drug Discovery
• Proteomics

Background:

• Sulfur(VI) fluorides (SFs) are versatile electrophiles for developing "beyond-cysteine" covalent inhibitors.
• SFs can modify proteins by targeting nucleophilic amino acids, expanding the scope beyond cysteine residues.
• Libraries of reactive fragments combined with mass spectrometry offer innovative strategies for ligand discovery.

Purpose of the Study:

• To develop and validate a screening approach utilizing SFs for identifying covalent inhibitors.
• To demonstrate the utility of SF-containing reactive fragments for targeting proteins of interest.
• To accelerate the discovery of novel "beyond-cysteine" covalent inhibitors.

Main Methods:

• Synthesis of SF-containing reactive fragment libraries.
• Direct-to-biology screening workflow for hit identification.
• Characterization of covalent modification sites, kinetics, and cellular target engagement.
• Crystallography for detailed molecular understanding of fragment-target interactions.

Main Results:

• Efficient identification of hit compounds for carbonic anhydrase II (CAII) and BCL6 using the SF screening approach.
• Detailed characterization of the most promising hits, including modification sites and kinetics.
• Structural insights into fragment binding obtained through crystallography.
• Demonstration of target engagement in cellular assays.

Conclusions:

• The developed screening protocol effectively exploits SF properties for accelerated discovery of "beyond-cysteine" covalent inhibitors.
• This approach broadens the possibilities for covalent modification of proteins, independent of cysteine residues.
• The methodology holds promise for expanding the liganded proteome and discovering novel chemical biology tools.