Computer-aided design and synthesis of nonpeptidic plasmepsin II and IV inhibitors

ChemMedChem. 2008 Sep;3(9):1323-36. doi: 10.1002/cmdc.200700270.

Abstract

Plasmepsins (Plm) II (EC number: 3.4.23.39) and IV (EC number: 3.4.23.B14) are aspartic proteases present in the food vacuole of the malaria parasite Plasmodium falciparum and are involved in host hemoglobin degradation. Based on our established efficient synthetic sequence, a series of inhibitors for Plm II and IV has been synthesized bearing a 2,3,4,7-tetrahydro-1H-azepine scaffold as the core structural element. During the computational design cycle, thorough investigations were carried out in order to find a reasonable theoretical binding mode for Plm II and IV. The conformation of Plm II in the crystal structure (PDB code: 1LF2) provides a good starting geometry for our virtual screening approach. In contrast, the only available co-crystal structure for Plm IV of P. falciparum (PDB code: 1LS5) appears inappropriate for inhibitor design. Therefore, a homology model was constructed based on the Plm II 1LF2 structure. A combinatorial docking run using FlexX(c) suggested compounds which, after synthesis, turned out to exhibit affinities in the sub-micromolar range. The observed structure-activity relationships of the synthesized compounds confirm the assumed binding mode for Plm II and IV. The best-binding inhibitors designed for Plm II and IV are devoid of any inhibitory potency against human cathepsin D (EC number: 3.4.23.5).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aspartic Acid Endopeptidases / antagonists & inhibitors*
  • Aspartic Acid Endopeptidases / chemistry
  • Azepines / chemical synthesis*
  • Azepines / pharmacology*
  • Binding Sites
  • Computer Simulation
  • Computer-Aided Design*
  • Crystallography, X-Ray
  • Drug Design*
  • Drug Evaluation, Preclinical
  • Enzyme Inhibitors / chemical synthesis*
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Ligands
  • Models, Chemical
  • Models, Molecular
  • Molecular Conformation
  • Plasmodium falciparum / enzymology
  • Protozoan Proteins
  • Stereoisomerism
  • Structure-Activity Relationship

Substances

  • Azepines
  • Enzyme Inhibitors
  • Ligands
  • Protozoan Proteins
  • Aspartic Acid Endopeptidases
  • plasmepsin
  • plasmepsin II