Rational design of peptide-based inhibitors of trypanothione reductase as potential antitrypanosomal drugs

The rational design of ligands for the substrate-binding site of a homology-modelled trypanothione reductase (TR) was performed. Peptides were designed to be selective for TR over human glutathione reductase (GR). The design process capitalized on the proposed differences between the activesites of TR and human GR, subsequently confirmed by the TR crystal structure. Enzyme kinetics confirmed that for T. cruzi TR benzoyl-Leu-Arg-Arg-ß-naphthylamide was an inhibitor (Ki 13.8 μM) linearly competitive with the native substrate, trypanothione disulphide, and did not inhibit glutathione reductase.