Characterization of Tf5 (α-KTx4.9) a potassium toxin from Tityus fasciolatus. Characterization of Tf5 (α-KTx4.9) from Tityus fasciolatus

Tf5 is a newly identified peptide from the venom of Tityus fasciolatus, an endemic scorpion species found in the Brazilian Cerrado ecosystem. The full-length cDNA sequence of the Tf5 gene was obtained from a previously constructed transcriptomic library, revealing a 177-nucleotide ORF (Open Reading Frame) that includes a mature KTx domain of 37 amino acids and six cysteine residues. Tf5 was purified from the venom gland, yielding a peptide with a molecular mass of 3,983.95 Da. Its K⁺-channel blocking activity was tested on Kv1.1, Kv1.2, Kv1.3, and Kv1.4 subtypes.