A cell-permeable, irreversible inhibitor of the trypsin-like, chymotrypsin-like, and peptidylglutamyl peptide hydrolysis activities of the 20S proteasome. It is believed that in vitro, the natural product, Lactacystin (Cat. No. 426100), acts as a precursor for clasto-lactacystin β-lactone, and the later is the sole species that interacts with the proteasome. Inhibits the proteasome in intact cells (IC₅₀ approximately 1 µM). clasto-Lactacystin β-lactone shows 5-10 fold greater potency than lactacystin in vitro.

A highly specific, cell-permeable, and irreversible 20S proteasome inhibitor. It is believed that in vitro, the natural product Lactacystin (Cat. No. 426100) acts as a precursor for clasto-lactacystin β-lactone and that the latter is the sole species that interacts with the proteasome.

Cell permeable: yes

Primary Target
20S proteasome

Product does not compete with ATP.

Reversible: no

Following reconstitution, aliquot and freeze (-20°C). Stock solutions are stable for up to 1 month at -20°C. Rapidly hydrolyzed in aqueous buffers.

Corey, E.J., and Wei-Dong, Z. 1999. Chem. Pharm. Bull. 47, 1.
Dick, L.R., et al. 1997. J. Biol. Chem. 272, 182.
Dick, L.R., et al. 1996. J. Biol. Chem.271, 7273.
Fenteany, G., et al. 1995. Science268, 726.

CALBIOCHEM is a registered trademark of Merck KGaA, Darmstadt, Germany

Toxicity: Standard Handling (A)