Aza-peptidyl Michael acceptors. A new class of potent and selective inhibitors of asparaginyl endopeptidases (legumains) from evolutionarily diverse pathogens

J Med Chem. 2008 May 8;51(9):2816-32. doi: 10.1021/jm701311r. Epub 2008 Apr 17.


Aza-peptide Michael acceptors with the general structure of Cbz-Ala-Ala-AAsn- trans-CH=CHCOR are a new class of inhibitors specific for the asparaginyl endopeptidases (AE) (legumains). Structure-activity relationships (SARs) were characterized for a set of 31 aza-peptide Michael acceptors with AEs derived from three medically important parasites: the protist Trichomonas vaginalis, the hard tick Ixodes ricinus, and the flatworm Schistosoma mansoni. Despite arising from phylogenetically disparate organisms, all three AEs shared a remarkably similar SAR with lowest IC50 values extending into the picomolar range. The results suggest an evolutionary constraint on the topography of the prime side of the active site. SAR also revealed that esters in the P1' position are more potent than disubstituted amides and that monosubstituted amides and alkyl derivatives show little or no inhibition. The preferred P1' residues have aromatic substituents. Aza-asparaginyl Michael acceptors react with thiols, which provides insight into the mechanism of their inhibition of asparaginyl endopeptidases.

Publication types

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

MeSH terms

  • Animals
  • Aza Compounds / chemical synthesis*
  • Aza Compounds / chemistry
  • Biotin / chemistry
  • Cysteine Endopeptidases / chemistry*
  • Cysteine Proteinase Inhibitors / chemical synthesis*
  • Cysteine Proteinase Inhibitors / chemistry
  • Dithiothreitol / chemistry
  • Inhibitory Concentration 50
  • Ixodes / enzymology*
  • Oligopeptides / chemical synthesis*
  • Oligopeptides / chemistry
  • Schistosoma mansoni / enzymology*
  • Structure-Activity Relationship
  • Sulfhydryl Compounds / chemistry
  • Trichomonas vaginalis / enzymology*


  • Aza Compounds
  • Cysteine Proteinase Inhibitors
  • Oligopeptides
  • Sulfhydryl Compounds
  • Biotin
  • Cysteine Endopeptidases
  • asparaginylendopeptidase
  • Dithiothreitol