Dihydroquinazolines as a novel class of Trypanosoma brucei trypanothione reductase inhibitors: discovery, synthesis, and characterization of their binding mode by protein crystallography.

Trypanothione reductase (TryR) is a genetically validated drug target in the parasite Trypanosoma brucei , the causative agent of human African trypanosomiasis. Here we report the discovery, synthesis, and development of a novel series of TryR inhibitors based on a 3,4-dihydroquinazoline scaffold. In addition, a high resolution crystal structure of TryR, alone and in complex with substrates and inhibitors from this series, is presented. This represents the first report of a high resolution complex between a noncovalent ligand and this enzyme. Structural studies revealed that upon ligand binding the enzyme undergoes a conformational change to create a new subpocket which is occupied by an aryl group on the ligand. Therefore, the inhibitor, in effect, creates its own small binding pocket within the otherwise large, solvent exposed active site. The TryR-ligand structure was subsequently used to guide the synthesis of inhibitors, including analogues that challenged the induced subpocket. This resulted in the development of inhibitors with improved potency against both TryR and T. brucei parasites in a whole cell assay.
AuthorsStephen Patterson, Magnus S Alphey, Deuan C Jones, Emma J Shanks, Ian P Street, Julie A Frearson, Paul G Wyatt, Ian H Gilbert, Alan H Fairlamb
JournalJournal of medicinal chemistry (J Med Chem) Vol. 54 Issue 19 Pg. 6514-30 (Oct 13 2011) ISSN: 1520-4804 [Electronic] United States
PMID21851087 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Ligands
  • Quinazolines
  • Recombinant Proteins
  • Trypanocidal Agents
  • NADH, NADPH Oxidoreductases
  • trypanothione reductase
  • Cell Line
  • Crystallography, X-Ray
  • Drug Design
  • Humans
  • Ligands
  • NADH, NADPH Oxidoreductases (antagonists & inhibitors, chemistry)
  • Protein Binding
  • Protein Conformation
  • Quinazolines (chemical synthesis, chemistry, pharmacology)
  • Recombinant Proteins (antagonists & inhibitors, chemistry)
  • Stereoisomerism
  • Structure-Activity Relationship
  • Trypanocidal Agents (chemical synthesis, chemistry, pharmacology)
  • Trypanosoma brucei brucei (drug effects, enzymology)
  • Trypanosoma cruzi (drug effects)

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