In contrast to all classical long-chain α-neurotoxins possessing the critical fifth disulfide bond, α-elapitoxin-Aa2a (α-EPTX-Aa2a), a novel long-chain α-neurotoxin from the common death adder Acanthophis antarcticus, lacks affinity for neuronal α7-type nicotinic acetylcholine receptors (nAChRs). α-EPTX-Aa2a (8850Da; 0.1-1μM) caused a concentration-dependent inhibition of indirect twitches, and...