F2X-Universal and F2X-Entry: Structurally Diverse Compound Libraries for Crystallographic Fragment Screening

Structure. 2020 Jun 2;28(6):694-706.e5. doi: 10.1016/j.str.2020.04.019. Epub 2020 May 14.


Crystallographic fragment screening (CFS) provides excellent starting points for projects concerned with drug discovery or biochemical tool compound development. One of the fundamental prerequisites for effective CFS is the availability of a versatile fragment library. Here, we report on the assembly of the 1,103-compound F2X-Universal Library and its 96-compound sub-selection, the F2X-Entry Screen. Both represent the available fragment chemistry and are highly diverse in terms of their 3D-pharmacophore variations. Validation of the F2X-Entry Screen in CFS campaigns using endothiapepsin and the Aar2/RNaseH complex yielded hit rates of 30% and 21%, respectively, and revealed versatile binding sites. Dry presentation of the libraries allows CFS campaigns to be carried out with or without the co-solvent DMSO present. Most of the hits in our validation campaigns could be reproduced also in the absence of DMSO. Consequently, CFS can be carried out more efficiently and for a wider range of conditions and targets.

Keywords: Aar2; FBDD; Prp8 RNaseH; X-ray crystallography; compound library; drug design; endothiapepsin; fragment screening; protein-protein complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspartic Acid Endopeptidases / chemistry*
  • Aspartic Acid Endopeptidases / metabolism*
  • Binding Sites
  • Crystallography, X-Ray
  • Databases, Chemical
  • Drug Discovery
  • Drug Evaluation, Preclinical
  • Models, Molecular
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*


  • Small Molecule Libraries
  • Aspartic Acid Endopeptidases
  • Endothia aspartic proteinase