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

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, 3306.24+/-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 omega-conotoxsins. Cvtxs-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, (C) 2000 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.