Table IV Effect of proteasome inhibitors on the digestion of the 30-mer substrate
No InhibitorMG-132Epoxomicin
Amount digested75.8%56.8%49.9%
N. of digestion products211813
Peptides involving dual cleavagea13 (61.9%)8 (44.4%)8 (61.5%)
N. of cleaved peptide bondsb22 (75.9%)23 (79.3%)18 (62.1%)
N. of productive species for the ligandc110
Relative yield of productive cleavagesd16.8%9.0%0
N. of destructive cleavages for the ligande6 (27.3%)6 (26.1%)4 (22.2%)
Relative yield of the destructive cleavagesd19.8%21.0%25.9%
Destruction/production ratio for the ligandf1.22.3
  • a Percent relative to the total number of digestion products.

  • b Percent relative to the total number of peptide bonds in the substrate.

  • c Peptides with the right C-terminus and right or extended N-terminus. Percent values are relative to the total number of digestion products.

  • d Added values from Table VIIS. Productive cleavages correspond to cleavage after R14.

  • e Cleaved peptide bonds implying destruction of the epitope. Percent values are relative to the total number of cleaved peptide bonds.

  • f Ratio between the joint relative yield of cleavages implying destruction of the natural ligand and that of the potentially productive peptides.