Organic dyes as small molecule protein-protein interaction inhibitors for the CD40-CD154 costimulatory interaction

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


It is becoming increasingly clear that small molecules can often act as effective protein-protein interaction (PPI) inhibitors, an area of increasing interest for its many possible therapeutic applications. We have identified several organic dyes and related small molecules that (i) concentration-dependently inhibit the important CD40-CD154 costimulatory interaction with activities in the low micromolar (mM) range, (ii) show selectivity toward this particular PPI, (iii) seem to bind on the surface of CD154, and (iv) concentration-dependently inhibit the CD154-induced B cell proliferation. They were identified through an iterative activity screening/structural similarity search procedure starting with suramin as lead, and the best smaller compounds, the main focus of the present work, achieved an almost 3-fold increase in ligand efficiency (ΔG0/nonhydrogen atom 1/40.8 kJ/NnHa) approaching the average of known promising small-molecule PPI inhibitors (~1.0 kJ/NnHa). Since CD154 is a member of the tumor necrosis factor (TNF) superfamily of cell surface interaction molecules, inhibitory activities on the TNF-R1-TNF-a interactions were also determined to test for specificity, and the compounds selected here all showed more than 30-fold selectivity toward the CD40-CD154 interaction. Because of their easy availability in various structural scaffolds and because of their good protein-binding ability, often explored for tissue-specific staining and other purposes, such organic dyes can provide a valuable addition to the chemical space searched to identify small molecule PPI inhibitors in general.

Original languageEnglish (US)
Pages (from-to)65-73
Number of pages9
JournalJournal of Molecular Recognition
Issue number1
StatePublished - Jan 1 2010


  • Binding free energy
  • CD40 ligand
  • Costimulation
  • Immune suppression
  • Protein-protein interaction

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology


Dive into the research topics of 'Organic dyes as small molecule protein-protein interaction inhibitors for the CD40-CD154 costimulatory interaction'. Together they form a unique fingerprint.

Cite this