Purification, structure determination and synthesis of covalitoxin‐II, a short insect‐specific neurotoxic peptide from the venom of the Coremiocnemis validus (Singapore tarantula)

Abstract
Spider venoms contain toxins that specifically immobilize and kill insects. We report the purification and characterization of a new insect‐specific toxin named covalitoxin‐II (Cvtx‐II; mass, 3406.24±0.64), from Coremiocnemis validus (Singapore tarantula) venom. The complete 31 amino acid sequence of Cvtx‐II has been determined and it shows less than 40% identity with spider toxins. However, Cvtx‐II has conserved cystine motif analogous to other spider and ω‐conotoxins. Cvtx‐II was chemically synthesized and identified with the native Cvtx‐II. Synthetic Cvtx‐II induced insect‐specific non‐lethal excitatory activity when injected into crickets, but not in cockroaches and mice.