A cell-permeable dipeptidylboronate compound that selectively inhibits 20S proteasome β5 ChTL/chymotrypsin- over β1 CL/caspase- and β2 TL/trypsin-like activity (
kinact/
Ki = 38,000, 5,700, and <100 M
-1s
-1, respectively, in human 20S proteasome assays using 10 M Suc-LLVY-AMC/Cat. No.
539142, 10 M Z-LLE-AMC/Cat. No.
539141, or 50 M Boc-LRR-AMC as substrate) via a covalent, slowly reversible manner, displaying much reduced potency against human chymotrypsin, cathepsin G, leukocyte elastase, and thrombin (K
i = 0.32, 0.63, 2.3, and 13 M, respectively, vs. 620 nM using rabbit muscle 20S). A widely used inhibitor both in cultures
in vitro and in animals
in vivo.
A cell-permeable dipeptidylboronate compound that selectively inhibits 20S proteasome β5 ChTL/chymotrypsin- over β1 CL/caspase- and β2 TL/trypsin-like activity (
kinact/
Ki = 38,000, 5,700, and <100 M
-1s
-1, respectively, in human 20S proteasome assays using 10 M Suc-LLVY-AMC/Cat. No.
539142, 10 M Z-LLE-AMC/Cat. No.
539141, or 50 M Boc-LRR-AMC as substrate; IC
50 in 1 h = 7, 74, and 4,200 nM, respectively) via a covalent, slowly reversible, interaction between the nucleophilic Thr1 hydroxy group/Thr1O
γ of the catalytic β subunit and the inhibitor′s electrophilic boronic moiety, displaying much reduced potency against human chymotrypsin, cathepsin G, leukocyte elastase, and thrombin (K
i = 0.32, 0.63, 2.3, and 13 M, respectively, vs. 620 nM using rabbit muscle 20S). A widely used inhibitor both in cultures
in vitro and in animals
in vivo. Despite being the first proteasome inhibitor approved by FDA for clinical anticancer treatment, its therapeutic efficacy continues to be hampered by off-target effects and dose-limiting toxicity.