The original encoded sequence of TsPep2 consists of 68 amino acids processed in a mature peptide of 29 amino acids with a final molecular weight of 2993.59 Da.[1][6]
TsPep2 differs in the mature sequence from TsPep3 only in one amino acid and TsPep1 shows 58,6% of sequence homology with Tspep2 and TsPep3.[1]
Eight cysteines establish four disulfide bridges and a C-terminal tyrosine amide is present in the 55th position.
Furthermore, TsPep2 sequence alignment shows that a part of the amino acid consensus sequence (CXXXKCCXC) involved in the pore blocking mechanism is present as in other known short scorpion toxins.[1][6][7]
The sequence alignment of TsPep2, TsPep1 and TsPep3.
It seems likely that TsPep2 has inhibitory actions on potassium channels, based on its sequence similarities in the C-terminal beta sheet with the potassium channel inhibitory alpha family (α-KTX) and on its similarities in the patterns of disulfide bridges with other short scorpion venom toxins.[1][6][8]
The biological function of TsPep2 is not clear yet, except from a small displacement on the 125I-KTX binding site on rat brain synaptosomes.[8] However, it has been shown that this peptide is not toxic to mice.[1][4] The LD50 of TsPep2 is currently unknown.
^ abcdefgPimenta, Adriano M.C.; Legros, Christian; Almeida, Flavia de Marco; Mansuelle, Pascal; Bougis, Pierre E.; Martin-Eauclaire, Marie F. (2003). "Novel structural class of four disulfide-bridged peptides from Tityus serrulatus venom". Biochemical and Biophysical Research Communications. 301 (4): 1086–1092. doi:10.1016/S0006-291X(03)00082-2. PMID12589824.
^ abEauclaire, Martin; France, Marie; Pimenta, Adriano M. C.; Bougis, Pierre E; de Lima, Maria-Elenal (2016). "Potassium channel blockers from the venom of the Brazilian scorpion Tityus serrulatus". Toxicon. 119: 253–265. doi:10.1016/j.toxicon.2016.06.016. PMID27349167.
