Peptidyl β-homo-aspartals (3-amino-4-carboxybutyraldehydes): New specific inhibitors of caspases

Sándor Bajusz, Irén Fauszt, Klára Németh, Éva Barabás, Attila Juhász, Miklós Patthy, Pál I. Bauer

Research output: Contribution to journalArticle

7 Citations (Scopus)


Interleukin-1β (IL-1β)-converting enzyme (ICE, caspase-1) processes the IL-1β precursor to mature inflammatory cytokine IL-1β. ICE has been identified as a unique cysteine protease, which cleaves Asp-X bonds, shows resistance to E-64 (an inhibitor of most cysteine proteases) and has a primary structure that is homologous to CED-3, a protein required for apoptosis (programmed cell death) in the nematode Caenorhabditis elegans, and to mammalian cysteine proteases that initiate and execute apoptosis, e.g., apopain/CPP32/caspase-3. The inhibitors of the ICE/CED-3 family or caspases, as they are called recently, may constitute therapeutic agents for amelioration of inflammatory and apoptosis-associated diseases. The most efficient ICE inhibitors are peptide aldehydes and peptidyl chloro or (acyloxy)methanes. A recent study revealed that both D- and L-Asp are accepted by ICE at the P1 of such inhibitors, and the peptidyl (acyloxy)methane analogues having the β-homo-aspartyl residue [-NH- CH(CH2COOH)-CH2CO-] are inactive. These findings we reexamined in terms of two issues. (a) ICE's resistance to E-64. Since it was thought to be caused by the enzyme's unique substrate specificity, we prepared substrate-based analogues, which were not inhibitory suggesting significant structural difference between the active centers of ICE and papain-like enzymes. (b) Tolerance for D-stereochemistry at the P1 of these inhibitors. In view of the mechanism of cysteine protease inhibition by peptidyl X-methanes, we thought that this phenomenon should be a general characteristic of cysteine proteases and the hAsp-containing analogues should behave as reversible inhibitors. Here, we analyzed the inhibition of ICE and apopain in comparison with that of papain, thrombin, and trypsin by peptide L/D-α-aldehydes and their L-β-homo-aldehyde [-NH-CH(R)-CH2-CHO] analogues. The following results were found. (1) The peptidyl L-β-homo-aspartals are potent inhibitors for caspases. (2) The L-β-homo analogues of peptide aldehyde inhibitors designed for other proteases are not inhibitory. (3) Unlike trypsin and thrombin (serine proteases), papain (cysteine protease) shows tolerance for D-stereochemistry at the P1 site of peptide aldehydes in proportion to the lability of the α-hydrogen of the P1-D-residue. The complete tolerance of ICE for P1-D-Asp may arise from this residue's high tendency to epimerization. (4) Reaction of cysteine proteases with peptide aldehyde or peptidyl X-methane inhibitors containing P1-D-residues may include α-proton abstraction followed by asymmetric induction leading to P1-L-residue-containing products.

Original languageEnglish
Pages (from-to)109-118
Number of pages10
JournalBiopolymers - Peptide Science Section
Issue number1
Publication statusPublished - Jun 26 1999


  • Caspases
  • Inhibitors
  • Interleukin-1β converting enzyme
  • Peptidyl β-homo-aspartals

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Biomaterials
  • Organic Chemistry

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