Efficient Ligand Discovery Using Sulfur(VI) Fluoride Reactive Fragments

15 December 2022, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


Sulfur(VI) fluorides (SFs) have emerged as valuable electrophiles for the design of 'beyond cysteine' covalent inhibitors, and offer potential for expansion of the liganded proteome. Since SFs target a broad range of nucleophilic amino acids, they deliver an approach for the covalent modification of proteins without requirement for a proximal cysteine residue. Further to this, libraries of reactive fragments present an innovative approach for the discovery of ligands and tools for proteins of interest by leveraging a breadth of mass spectrometry analytical approaches. Herein, we report a screening approach that exploits the unique properties of SFs for this purpose. Libraries of SF-containing reactive fragments were synthesised, and a direct-to-biology workflow was taken to efficiently identify hit compounds for CAII and BCL6. The most promising hits were further characterised to establish the site(s) of covalent modification, modification kinetics, and target engagement in cells. Crystallography was used to gain a detailed molecular understanding of how these reactive fragments bind to their target. It is anticipated that this screening protocol can be used for the accelerated discovery of ‘beyond cysteine’ covalent inhibitors.


sulfonyl fluoride
sulfur(VI) fluroide
reactive fragment
ligand discovery
mass spectrometry
carbonic anhydrase II
B-cell lymphoma 6
beyond cysteine

Supplementary materials

Supplementary Information - Efficient Ligand Discovery Using Sulfur(VI) Fluoride Reactive Fragments
Supplementary Information - Efficient Ligand Discovery Using Sulfur(VI) Fluoride Reactive Fragments


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.