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Crystallographic Fragment Screening against COVID-19 and other diseases

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The Frag Xtal Screen can help to develop new drug candidates against COVID-19 and other diseases.


  • ...are small organic molecules (100-250 Da)
  • ...have a low binding affinity
  • ...show high binding efficiency*
  • ...cover a large chemical space even by small libraries
* binding efficiency = high binding energy / molecular mass

The structural analysis of small fragments bound to a specific protein target allows a structure-based development of high-affinity lead candidates. Skip time-consuming prescreening and use crystallographic fragment screening as first screening approach!

Crystallographic Fragment Screening

  • Can cover hits that are not identified by other prescreening methods[1-3]
  • Probes the whole protein surface and not only the active site
  • Provides information about the binding mode of the fragments at atomic level
  • Allows structure-based fragment evolution towards nanomolar lead structures[4]

Crystallographic Fragment Screening

Figure adapted from [4]
* binding efficiency = high binding energy / molecular mass

What you need

  • Protein crystals of the target or high-purity protein and an established crystallization protocol

What you get

  • 3 Well crystallization plate (Cat. No. CPL-164) spotted with 96 different fragments (2 x 50 nmol of each fragment, third protein well is kept free)

  • Fragments were chosen to be
    • proven binders
    • chemically diverse
    • highly soluble (> 90 mM)

How it works

  1. Remove sealing foil of the fragment plate carefully
  2. Add 30 µl crystallization buffer to the reservoir (manually or by robot)
  3. Add 0.5 µl crystallization buffer on dried fragments (manually or by robot)
  4. Add 1-2 crystals per drop
  5. Seal the plate & incubate 1 - 48 h
  6. Fish & cryo-cool at least one crystal per condition

The Frag Xtal Screen was developed in cooperation with the HZB MX-group at BESSY II (AG Weiss) and the Institute of Pharmaceutical Chemistry, University of Marburg (AG Klebe).
It is ready to use and provides an easy entry into crystallographic fragment screening. With practical skills in transferring crystals and cryocooling, 96 distinct fragments can be screened within one week.

Questions or inquiries?

Christin Reuter

E-Mail Christin for technical inquiries or further information: xtals@jenabioscience.com


[1] Huschmann et al. (2016) Structures of endothiapepsin-fragment complexes from crystallographic fragment screening using a novel, diverse and affordable 96-compound fragment library. Acta Cryst F 72:346.
[2] Schiebel et al. (2016) Six Biophysical Screening Methods Miss a Large Proportion of Crystallographic Discovered Fragment Hits: A Case Study. ACS Chem. Biol. 11:1693.
[3] Schiebel et al. (2015) One Question, Multiple Answers: Biochemical and Biophysical Screening Methods Retrieve Deviating Fragment Hit Lists. ChemMedChem 10:1511.
[4] Rees et al. (2004) Fragment-based lead discovery. Nature Reviews Drug Discovery 3:660.