From −110 to +10 mV we observed the

normal decrease of the Af and As components, but also the increase of the Ass component as shown in the inset to Fig. 2 upper-right (see under Nav1.1 panel). The steady-state inactivation resulted to have a sigmoidal voltage-dependent curve, which, differently from control curves, was characterized by a DAPT mw non complete inactivation and a pedestal at depolarized potentials. This last Ass effect indirectly and strongly affected the window current (normally negligible in control), thus producing a small and not always significant left-shift of the activation curves. When necessary the dose-response relationships of As and Ass components were computed in Fig. 4. In order to visualize the 3D structure of each studied toxin, models of CGTX-II, δ-AITX-Bcg1a and δ-AITX-Bcg1b were constructed using the SWISS-MODEL structure homology-modeling server (http://swissmodel.expasy.org/workspace/) [3]. The tri-dimensional structure of Anthopleurin-A toxin (determined by NMR) [24] (PDB ID: 1ahl) was employed as a template for all models.

The structures were GDC0199 drawn and visualized by DeepView/PDB viewer [12] (http://www.expasy.org/spdbv, version 4.0.1) and PyMOL (The PyMOL Molecular Graphics System, Version 1.2, Schrödinger, LLC., http://www.pymol.org), and were rendered by PovRay (version 3.6 by Persistence of Vision Raytracer, Pty., Ltd.). All the three models were validated by the tools Anolea, DFire, QMEAN, Gromos, Promotif and ProCheck, available in the “structure assessment” tool of the SWISS-MODEL structure homology-modeling server. The toxins employed in this study were obtained according to the previously described procedures [35] and [36]. Considering an urgent need for standardization of nomenclature of animal toxins, especially in sea anemones, we employed a rationale recently suggested [17]

for the novel components eluted during RP-HPLC at 30.24 and 30.57 min from the neurotoxic fraction of B. cangicum venom. second These peptides were named as δ-Actitoxin-Bcg1a (δ-AITX-Bcg1a) and δ-Actitoxin-Bcg1b (δ-AITX-Bcg1b), respectively. This rationale follows the biological effects exerted by the toxin (δ letter for toxins that delay the inactivation process of ion channels) and the family of the organism which the toxin is derived (“Actitoxin” for toxins isolated from sea anemones of the “Actiniidae” family). Also, full sequences of each peptide were determined in this work. Both sequences were deposited at Uniprot server (http://www.ebi.ac.uk/uniprot/) and their accession numbers were assigned as P86459 and P86460, respectively. As CGTX-II (Uniprot ID: P0C7P9) had already been published [35], we have not changed its name.