Characterization of a new peptide from Tityus serrulatus scorpion venom which is a ligand of the apamin-binding site

Abstract A new ligand (Ts κ) of the apamin binding site on rat brain synaptosomes ( K 0.5 = 300 pM) was purified and characterized from the venom of Tityus serrulatus . It is a polypeptide toxin of 35 amino acid residues, with three disulfide bridges. Its cDNA was amplified from a venom gland cDNA library and the nucleotide sequence determined. A model of Ts κ was constructed by amino acid replacement using charybdotoxin structure as determined by 1 H nuclear magnetic resonance as starting model.