Fragment-Based Discovery of a Regulatory Site in Thioredoxin Glutathione Reductase Acting as "Doorstop" for NADPH Entry

ACS Chem Biol. 2018 Aug 17;13(8):2190-2202. doi: 10.1021/acschembio.8b00349. Epub 2018 Jun 11.


Members of the FAD/NAD-linked reductase family are recognized as crucial targets in drug development for cancers, inflammatory disorders, and infectious diseases. However, individual FAD/NAD reductases are difficult to inhibit in a selective manner with off-target inhibition reducing usefulness of identified compounds. Thioredoxin glutathione reductase (TGR), a high molecular weight thioredoxin reductase-like enzyme, has emerged as a promising drug target for the treatment of schistosomiasis, a parasitosis afflicting more than 200 million people. Taking advantage of small molecules selected from a high-throughput screen and using X-ray crystallography, functional assays, and docking studies, we identify a critical secondary site of the enzyme. Compounds binding at this site interfere with well-known and conserved conformational changes associated with NADPH reduction, acting as a doorstop for cofactor entry. They selectively inhibit TGR from Schistosoma mansoni and are active against parasites in culture. Since many members of the FAD/NAD-linked reductase family have similar catalytic mechanisms, the unique mechanism of inhibition identified in this study for TGR broadly opens new routes to selectively inhibit homologous enzymes of central importance in numerous diseases.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anthelmintics / chemistry
  • Anthelmintics / pharmacology*
  • Crystallography, X-Ray
  • Drug Discovery
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Mice
  • Models, Molecular
  • Multienzyme Complexes / antagonists & inhibitors*
  • Multienzyme Complexes / chemistry
  • Multienzyme Complexes / metabolism
  • NADH, NADPH Oxidoreductases / antagonists & inhibitors*
  • NADH, NADPH Oxidoreductases / chemistry
  • NADH, NADPH Oxidoreductases / metabolism
  • NADP / metabolism*
  • Schistosoma mansoni / chemistry
  • Schistosoma mansoni / drug effects*
  • Schistosoma mansoni / enzymology*
  • Schistosoma mansoni / metabolism
  • Schistosomiasis mansoni / drug therapy
  • Schistosomiasis mansoni / parasitology*


  • Anthelmintics
  • Enzyme Inhibitors
  • Multienzyme Complexes
  • NADP
  • NADH, NADPH Oxidoreductases
  • thioredoxin glutathione reductase