The primary structure of noxiustoxin: A K+ channel blocking peptide, purified from the venom of the scorpion Centruroides noxius Hoffmann

Abstract

Noxiustoxin, component II-11 from the venom of scorpion Centruroides noxius Hoffmann, was obtained in pure form after fractionation by Sephadex G-50 chromatography followed by ion exchange separation on carboxy-methylcellulose columns (17). The primary structure of Noxiustoxin, a polypeptide 39 amino acid residues long was determined by automatic Edman degradation and chemical cleavage with cyanogen bromide followed by amino acid analysis of the two resulting peptides. Its sequence is: Thr-Ile-Ile-Asn-Val-Lys-Cys-Thr-Ser-Pro-Lys-Gln-Cys-Ser-Lys-Pro-Cys-Lys-Glu-Leu-Tyr-Gly-Ser-Ser-Ala-Gly-Ala-Lys-Cys-Met-Asn-Gly-Lys-Cys-Lys-Cys-Tyr-Asx-Asn, with a molecular weight of 4,184±6. No histidine, arginine, tryptophan or phenylalanine was found. Noxiustoxin is the first short toxin directed against mammals and the first K+ channel blocking polypeptide-toxin (4) found in scorpion venoms. © 1982 Carlsberg Laboratory.