Title: Charybdotoxin
CAS Registry Number: 95751-30-7
Additional Names: ChTX; CTX
Molecular Formula: C176H277N57O55S7
Molecular Weight: 4295.89
Percent Composition: C 49.21%, H 6.50%, N 18.58%, O 20.48%, S 5.22%
Literature References: Peptide inhibitor of K+ channels isolated from the venom of the scorpion Leiurus quinquestriatus var. hebraeus. Single chain of 4.3 kDa comprised of 37 amino acids with 3 disulfide linkages. Identification: C. Miller et al., Nature 313, 316 (1985). Purification and amino acid sequence: G. Gimenez-Gallego et al., Proc. Natl. Acad. Sci. USA 85, 3329 (1988). Synthesis: E. E. Sugg et al., J. Biol. Chem. 265, 18745 (1990); P. Lambert et al., Biochem. Biophys. Res. Commun. 170, 684 (1990). NMR structural study: F. Bontems et al., Eur. J. Biochem. 196, 19 (1991). Mechanism of channel block: R. MacKinnon, C. Miller, J. Gen. Physiol. 91, 335 (1988). Characterization of binding sites: J. Vázquez et al., J. Biol. Chem. 264, 20902 (1989); J. Vázquez et al., ibid. 265, 15564 (1990). Use as probe for K+ channels: M. Garcia, G. Gimenez-Gallego, US 4960867 (1990 to Merck & Co.).
Properties: Extinction coefficient: 1.52 (mg/ml)-1cm-1 at 280 nm; 15.05 (mg/ml)-1cm-1 at 215 nm.
Use: Biochemical probe.
Chaulmoogra Oil Chaulmoogric Acid Chavicine Chavicol Cheirolin

PDB 2crd EBI.jpg
Refined model of Charybdotoxin. PDB 2crd. [1]
Organism Leiurus quinquestriatus hebraeus
Symbol ChTX
Alt. symbols ChTX-Lq1, ChTx-a
CAS number 95751-30-7
PDB 2crd More structures
UniProt P13487
Other data

Charybdotoxin (CTX) is a 37 amino acid neurotoxin from the venom of the scorpion Leiurus quinquestriatus hebraeus (Deathstalker) that blocks calcium-activated potassium channels.[2] This blockade causes hyperexcitability of the nervous system. It is a close homologue of agitoxin and both toxins come from Leiurus quinquestriatus hebraeus.