The new kappa-KTx 2.5 from the scorpion Opisthacanthus cayaporum

► We describe the κ-KTx2.5 and show it is a blocker of hKv1.1, and hKv1.4 channels. ► CD spectra showed a predominance of α-helices at different temperatures in water and water/TFE. ► κ-KTx2.5 had no activity on other ion channels, on bacterial growth and on smooth muscle tissue. ► A structural model of the kappa-KTx2.5-Kv1.2 complex is presented.