Human caspase-3 inhibition by Z-tLeu-Asp-H: tLeu(P2) counterbalances Asp(P4) and Glu(P3) specific inhibitor truncation.
Caspase-3 is responsible for the cleavage of several proteins including the nuclear enzyme poly(ADP-ribose) polymerase (PARP). Designed on the cleavage site of PARP, Ac-Asp-Glu-Val-Asp-H has been reported as a highly specific inhibitor. To overcome the susceptibility to proteolysis, the intrinsic instability, and the scarce membrane permeability of tetra-peptidyl aldehydes, di- and tri-peptidyl caspase-3 inhibitors have been synthesized. Here, the synthesis and the inhibition properties of peptidyl aldehydes Z-tLeu-Asp-H, Z-tLeu-Val-Asp-H, and Z-Val-tLeu-Asp-H are reported. Z-tLeu-Asp-H, Z-tLeu-Val-Asp-H, and Z-Val-tLeu-Asp-H inhibit competitively human caspase-3 activity in vitro with K(i)(0)=3.6nM, 18.2nM, and 109nM, respectively (pH 7.4 and 25 degrees C). Moreover, Z-tLeu-Asp-H impairs apoptosis in human DLD-1 colon adenocarcinoma cells without affecting caspase-8. Therefore, Ac-Asp-Glu-Val-Asp-H can be truncated to Z-tLeu-Asp-H retaining nanomolar inhibitory activity in vitro and displaying action in whole cells, these properties reflect the unprecedented introduction of the bulky and lipophilic tLeu residue at the P(2) position.
Department of Drug Sciences, University 'Gabriele D'Annunzio', Via dei Vestini 31, I-66013 Chieti, Italy.
Patrizia
P
Colantonio
Loris
L
Leboffe
Alessandro
A
Bolli
Maria
M
Marino
Paolo
P
Ascenzi
Grazia
G
Luisi
D000595:Amino Acid Sequence; D017209:Apoptosis; D001216:Asparagine / Q000737:chemistry; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D015853:Cysteine Proteinase Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D004151:Dipeptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D018698:Glutamic Acid / Q000737:chemistry; D006801:Humans; D007930:Leucine / Q000737:chemistry; D015394:Molecular Structure
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; C533608:benzyloxycarbonyl-tert-leucyl-aspartic acid; D018698:Glutamic Acid; D001216:Asparagine; D007930:Leucine