Purification and Characterization of Two Neurotoxins BmKNT1 and BmKNT2 from the Scorpion Buthus martensii karsch venom.

Scorpion venom is a heterogeneous mixture of proteins and peptides, many of which have multiple bioactivities, including antitumor activity, modulation of ion channels, analgesia, and anti-inflammatory effects. This study, two peptides named BmKNT1 and BmKNT2 were isolated and purified from the Buthus martensii Karsch (BmK) venom by gel filtration chromatography (GFC), ion-exchange chromatography (IEC) and Reverse phase high-performance liquid chromatography (RP-HPLC), respectively. The primary structure of BmKNT1 (69 amino acid residues, theoretical pI/Mw: 7.66/7660.5 Da) and BmKNT2 (64 amino acid residues, theoretical pI/Mw: May 6, 7270.33) were determined by a combination of Edman degradation and MALDI-TOF-MS/MS sequencing analysis. It showed a high similarity to that of other scorpion neurotoxins. The Effects of both neurotoxins on Na+-channel, K+-channel and Ca2+-channel in rat dorsal root ganglion (DRG) were determined at 100 μg/ml. The results showed BmKNT2 had inhibitory activity on K+-channels expressed on DRG cells, which is a typical characteristic of voltage-gated potassium channel pore area inhibitors. On the contrary, BmKNT1 has activation activity on the K+-channel in rat DRG, and both toxins have inhibitory activity on Ca2+-channels in rat DRG.