SsTx Toxin

Potassium channel toxin SsTx, Ssm spooky toxin
A Blocker of KCNQ and KV1.3 Channels
Cat #: STS-700
  • Lyophilized Powder
  • Bioassay Tested
  • Origin Scolopendra mutilans (Chinese red-headed centipede).
    Source Synthetic peptide.
    MW: 6018 Da.
    Purity: >98% (HPLC)
    Formulation Lyophilized powder.
    Effective concentration 2-5 µM.
    Sequence EVIKKDTPYKKRKFPYKSECLKACATSFTGGDESRIQEGKPGFFKCTCYFTTG.
    Modifications Disulfide bonds between Cys20-Cys46 and Cys24-Cys48.
    Structure
    Molecular formula C270H413N69O79S4.
    Activity Blocks voltage-gated potassium channels KCNQ4, KCNQ1, KCNQ2 and KCNQ51 and KV1.32.
    References - Activity
    1. Luo, L. et al. (2018) Proc. Natl. Acad. Sci. U.S.A. 115, 1646.
    2. Du, C. et al. (2019) Toxins (Basel) 11, 76.

    Storage before reconstitution Shipped at room temperature. Product as supplied can be stored intact at room temperature for several weeks. For longer periods, it should be stored at -20°C.
    Reconstitution Any other aqueous buffer. Centrifuge all product preparations before use (10000 x g 5 min).
    Storage after reconstitution Up to two weeks at 4°C or three months at -20°C.
    Our bioassay
    Alomone Labs SsTx Toxin inhibits the current of KCNQ2 channels expressed in Xenopus oocytes.
    A. Representative time course of KCNQ2 channel current inhibition by SsTx Toxin (#STS-700). Membrane potential was held at -80 mV, current was elicited by a 1000 ms voltage step to 0 mV every 10 sec, and reversibly inhibited by application of 4 µM SsTx Toxin (green). B. Superimposed traces of KCNQ2 current following the application of control (black) and of 4 µM SsTx Toxin (green), taken from the recording in A.
    Alomone Labs SsTx Toxin inhibits heteromeric KCNQ2/3 channel current expressed in HEK-293T cells.
    Transfected cells were stimulated by a 1.5 sec voltage step from the holding potential of -70 mV to 0 mV using whole-cell voltage clamp. A. Representative current traces upon application of control (black), 2 µM (red) and 5 µM (blue) SsTx Toxin (#STS-700), and after wash-out (gray). B. Representative time course of KCNQ2/3 current, reversibly inhibited by 2 µM and 5 µM SsTx Toxin. C. Representative traces of KCNQ2/3 current upon application of control (black), 10 µM SsTx Toxin (red), and after wash-out (gray). C. Representative time course of KCNQ2/3 current, reversibly inhibited by 10 µM SsTx Toxin. D. Average inhibition (%) of KCNQ2/3 current in response to various SsTx Toxin concentrations (n=5 each).
    Results were kindly provided by Prof. Anastasios Tzingounis, Dept. of Physiology & Neurobiology, University of Connecticut, USA.
    References - Scientific Background
    1. Luo, L. et al. (2018) Proc. Natl. Acad. Sci. U.S.A. 115, 1646.
    2. Wang, J.J. and Li, Y. (2016) Acta Pharmacol. Sin. 37, 25.
    3. Du, C. et al. (2019) Toxins (Basel) 11, 76.

    Scientific background

    SsTx Toxin is a peptide toxin originally isolated from the Chinese red-headed centipede venom. SsTx structure consists of amino acids in position 12 and 13 which form a positively charged surface and two disulphide bridges. It is the first peptide toxin found to potently and selectively block KCNQ (KV7) channels, members of voltage-gated potassium (KV) channel family1 with IC50 values of 2.5, 2.8, 2.7, and 2.7 μM for KCNQ4, KCNQ1, KCNQ2, and KCNQ5 respectively1. The the toxin also blocks KV1.3 channel with an IC50 value of ~5 μM3.

    SsTx blocks progressively less when the membrane potential becomes more depolarized, and high K+ concentrations increase the IC50 values, suggesting that the toxin binds to the outer pore domain of KCNQ channels1.

    KCNQ is a family of multifunctional K+ channels that are involved in a variety of physiological functions, including cardiac action potential repolarization, coronary circulation and reactive hyperemia, and cerebral neuron excitation. These channels are considered to be potential therapeutic targets for a variety of neuronal disorders1,2.

    Target KCNQ1, KCNQ2, KCNQ4, KCNQ5, KV1.3 channels
    Net Peptide Content: 100%
    Last update: 03/03/2019

    SsTx Toxin (#STS-700) is a highly pure, synthetic, and biologically active peptide toxin.

    For research purposes only, not for human use