Blanc E, Sabatier J M, Kharrat R, Meunier S, el Ayeb M, Van Rietschoten J, Darbon H
AFMB, CNRS UPR 9039, IFR1, Marseille, France.
Proteins. 1997 Nov;29(3):321-33.
Maurotoxin (MTX), purified from the scorpionid Scorpio maurus is a potent ligand for potassium channels. It shows a broad specificity as being active on Kv1.1 (Kd = 37 nM), Kv1.2 (Kd = 0.8 nM), Kv1.3 (Kd = 150 nM) voltage-gated potassium channels, as well as on small-conductance calcium-activated potassium channels. It has a unique disulfide pairing among the scorpion toxins family. The solution structure of MTX has been determined by 2D-NMR techniques, which led to the full description of its 3D conformation: a bended helix from residues 6 to 16 connected by a loop to a two-stranded antiparallel beta sheet (residues 23 to 26 and 28 to 31). The interaction of MTX with the pore region of the Kv1.2 potassium channel has been modeled according to their charge anisotropy. The structure of MTX is similar to other short scorpion toxins despite its peculiar disulfide pairing. Its interaction with the Kv1.2 channel involves a dipole moment, which guides and orients the toxin onto the pore, toward the binding site, and which thus is responsible for the specificity.
从蝎类动物天蝎座中纯化得到的毛蝎毒素（MTX）是钾通道的一种强效配体。它具有广泛的特异性，对电压门控钾通道Kv1.1（解离常数Kd = 37 nM）、Kv1.2（Kd = 0.8 nM）、Kv1.3（Kd = 150 nM）以及小电导钙激活钾通道均有活性。在蝎毒素家族中，它具有独特的二硫键配对方式。MTX的溶液结构已通过二维核磁共振技术确定，这使得对其三维构象有了全面描述：从第6位到第16位残基形成一个弯曲的螺旋，通过一个环与一个双股反平行β折叠（第23位到第26位残基以及第28位到第31位残基）相连。根据电荷各向异性，对MTX与Kv1.2钾通道孔区域的相互作用进行了建模。尽管MTX具有独特的二硫键配对，但它的结构与其他短蝎毒素相似。它与Kv1.2通道的相互作用涉及一个偶极矩，该偶极矩将毒素引导并定向到孔上，朝向结合位点，因此决定了特异性。
