The cystine-stabilized α-helix: A common structural motif of ion-channel blocking neurotoxic peptides

Neurotoxic peptides from venoms of scorpions and honey bees exhibit a consensus pattern in the two disulfide bridgings related to the sequence portions Cys‐X‐Cys and Cys‐X‐X‐X‐Cys. A revised three‐dimensional structure of charybdotoxin, as determined by two‐dimensional nmr spectroscopy, confirms that the consensus cystine dislocation generates in all these toxins a common structural element, i.e., the cystine‐stabilized α‐helical (CSH) motif, which may be correlated with their common ion channel blocking activity.