Design of antinociceptive peptide by grafting domains between scorpion β-neurotoxins.

Neurotoxic peptides from venomous animals have been pointed out as antinociceptive therapeutic leads. Venom peptides have modulation properties on isoforms of voltage-gated sodium channels (VGSC), associated with pathologies such as neuropathic or inflammatory pain. The β-neurotoxins obtained from scorpion venoms are peptides that can alter the kinetics of VGSC by binding to its receptor site 4. CeII8 is a non-lethal scorpion β-neurotoxin that has been reported to interact with hNaV1.7, a VGSC isoform related to the codification and processing of painful stimulus (nociception), and it is involved in pain pathologies. On the other hand, CssII is a lethal scorpion β-neurotoxin that binds mainly to site 4 of hNav1.6. Because of this, we used computational methods and the amino acid sequence of the novo recombinant neurotoxin rCssII-RCR to graft in some of its domains existing amino acids from the non-lethal CeII8 to generate a chimeric peptide with antinociceptive activity, named rCssII-Del-D23A-TCD. This peptide variant was found to have antinociceptive activity in inflammatory and neuropathic pain models with an effect comparable to the mu-opioid receptor agonists DAMGO (H-Tyr-D-Ala-Gly-N(Me) Phe-Gly-ol).