K⁺ channel blocker

Charybdotoxin was originally isolated from the venom of the Israeli scorpion Leiurus quinquestriatus hebraeus. Charybdotoxin blocks KCa1.1 (large conductance Ca²⁺ activated K⁺, Slo) channels in nanomolar concentrations as as well as Kv1.2 (Kd, 14 nM) and Kv1.3 (Kd, 2.6 nM) channels.). However, experiments with cloned KCa1.1 channels demonstrate the strong effect of the slob subunits on the potency of block by Charybdotoxin. This product is a recombinant peptide expressed in and extracted from E. coli.