Clasto-lactacystin β-lactone, also known as Omuralide and β-Clastolactacystin, targets ubiquitins. It is an active metabolite of lactacystin which induces differentiation and inhibition of cell cycle progression in several tumor cell lines. The inhibitor irreversibly alkylates subunit X of the 20s proteasome. Inhibition of proteasome peptidase activity results in the accumulation of various ubiquitinated proteins which normally undergo rapid degredation. Therefore, the effects are pleiotropic and largely depend on the expression patter of signaling proteins within the treated cell.

Omuralide

≥98% by HPLC

Clasto-lactacystin β-lactone inhibits ubiquitin proteasome pathways in cell culture with an IC50 value of 1 µM.

2.18 mM solution (0.05% by weight)

Solution in methyl acetate

Store at or below –20°C. Solid form is stable at least 12 months from date of receipt, when stored as directed. Do not store aqueous solutions for more than one day.

1. Omura, S., et al., J. Antibotics 1991;44:113-116.
2. Corey, E.J., et al., J. Am. Chem. Soc. 1992;114:10677-10678.
3. Fenteany, G., et al., J Biol. Chem. 1998;273(15):8545-8548.

Ubiquitin

Inhibitor