Identification of Small-Molecule Frequent Hitters of Glutathione S-Transferase-Glutathione Interaction

J Biomol Screen. 2016 Jul;21(6):596-607. doi: 10.1177/1087057116639992. Epub 2016 Apr 4.


In high-throughput screening (HTS) campaigns, the binding of glutathione S-transferase (GST) to glutathione (GSH) is used for detection of GST-tagged proteins in protein-protein interactions or enzyme assays. However, many false-positives, so-called frequent hitters (FH), arise that either prevent GST/GSH interaction or interfere with assay signal generation or detection. To identify GST-FH compounds, we analyzed the data of five independent AlphaScreen-based screening campaigns to classify compounds that inhibit the GST/GSH interaction. We identified 53 compounds affecting GST/GSH binding but not influencing His-tag/Ni(2+)-NTA interaction and general AlphaScreen signals. The structures of these 53 experimentally identified GST-FHs were analyzed in chemoinformatic studies to categorize substructural features that promote interference with GST/GSH binding. Here, we confirmed several existing chemoinformatic filters and more importantly extended them as well as added novel filters that specify compounds with anti-GST/GSH activity. Selected compounds were also tested using different antibody-based GST detection technologies and exhibited no interference clearly demonstrating specificity toward their GST/GSH interaction. Thus, these newly described GST-FH will further contribute to the identification of FH compounds containing promiscuous substructures. The developed filters were uploaded to the OCHEM website ( and are publicly accessible for analysis of future HTS results.

Keywords: AlphaScreen; GST; frequent hitter; glutathione; high-throughput screening.

MeSH terms

  • Glutathione / antagonists & inhibitors
  • Glutathione / chemistry*
  • Glutathione Transferase / antagonists & inhibitors
  • Glutathione Transferase / chemistry*
  • High-Throughput Screening Assays / methods*
  • Humans
  • Protein Interaction Maps / drug effects
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*
  • Substrate Specificity


  • Small Molecule Libraries
  • Glutathione Transferase
  • Glutathione