Modulation of the inhibitor properties of dipeptidyl (acyloxy)methyl ketones toward the CaaX proteases

Bioorg Med Chem. 2010 Sep 1;18(17):6230-7. doi: 10.1016/j.bmc.2010.07.041. Epub 2010 Jul 21.


Dipeptidyl (acyloxy)methyl ketones (AOMKs) have been identified as mechanism-based inhibitors of certain cysteine proteases. These compounds are also inhibitors of the integral membrane proteins Rce1p and Ste24p, which are proteases that independently mediate a cleavage step associated with the maturation of certain isoprenylated proteins. The enzymatic mechanism of Rce1p is ill-defined, whereas Ste24p is a zinc metalloprotease. Rce1p is required for the proper processing of the oncoprotein Ras and is viewed as a potential target for cancer therapy. In this study, we synthesized a small library of dipeptidyl AOMKs to investigate the structural elements that contribute to the inhibitor properties of this class of molecules toward Rce1p and Ste24p. The compounds were evaluated using a fluorescence-based in vitro proteolysis assay. The most potent dipeptidyl AOMKs contained an arginine residue and the identity of the benzoate group strongly influenced potency. A 'warhead' free AOMK inhibited Rce1p and Ste24p. The data suggest that the dipeptidyl AOMKs are not mechanism-based inhibitors of Rce1p and Ste24p and corroborate the hypothesis that Rce1p is not a cysteine protease.

Publication types

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

MeSH terms

  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacology
  • Cysteine Proteases / genetics
  • Cysteine Proteases / metabolism*
  • Dipeptides / chemistry
  • Dipeptides / pharmacology*
  • Drug Screening Assays, Antitumor
  • Ketones / chemistry
  • Ketones / pharmacology*
  • Membrane Proteins / antagonists & inhibitors*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Metalloendopeptidases / antagonists & inhibitors*
  • Metalloendopeptidases / genetics
  • Metalloendopeptidases / metabolism
  • Proprotein Convertases / antagonists & inhibitors*
  • Proprotein Convertases / genetics
  • Proprotein Convertases / metabolism
  • Protease Inhibitors / chemistry
  • Protease Inhibitors / pharmacology*
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / antagonists & inhibitors*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Substrate Specificity


  • Antineoplastic Agents
  • Dipeptides
  • Ketones
  • Membrane Proteins
  • Protease Inhibitors
  • Saccharomyces cerevisiae Proteins
  • Cysteine Proteases
  • Proprotein Convertases
  • RCE1 protein, S cerevisiae
  • Metalloendopeptidases
  • STE24 protein, S cerevisiae