Utkin Y N, Kukhtina V V, Maslennikov I V, Eletsky A V, Starkov V G, Weise C, Franke P, Hucho F, Tsetlin V I
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, GSP-7 V-437, 11781, Moscow, Russia.
Toxicon. 2001 Jul;39(7):921-7. doi: 10.1016/s0041-0101(00)00223-3.
With the purpose of studying structure-function relationships among weak neurotoxins (called so because of their low toxicity), we have isolated a toxin (WTX) from the venom of cobra Naja kaouthia using a combination of gel-filtration and ion-exchange chromatography. The amino acid sequence of the isolated toxin was determined by means of Edman degradation and MALDI mass spectrometry, the primary structure obtained being confirmed by 1H-NMR in the course of spatial structure analysis. The WTX sequence differs slightly from that of the toxin CM-9a isolated earlier from the same venom (Joubert and Taljaard, Hoppe-Seyler's Z. Physiol. Chem., 361 (1980) 425). The differences include an extra residue (Trp36) between Ser35 and Arg37 as well as interchanging of two residues (Tyr52 and Lys50) in the C-terminal part of the toxin molecule. These changes improve the alignment that can be made with other weak neurotoxin sequences. An extended sequence comparison reveals that WTX is the first case of a tryptophan-containing weak neurotoxin isolated from cobra venom. WTX was found to compete with radioiodinated alpha-bungarotoxin for binding to the membrane-bound nicotinic acetylcholine receptor from Torpedo californica.
为了研究弱神经毒素（因其低毒性而得名）之间的结构 - 功能关系，我们使用凝胶过滤和离子交换色谱相结合的方法，从眼镜蛇纳吉亚卡奥蒂亚的毒液中分离出一种毒素（WTX）。通过埃德曼降解法和基质辅助激光解吸电离质谱法测定了分离毒素的氨基酸序列，并在空间结构分析过程中通过1H - NMR对获得的一级结构进行了确认。WTX序列与先前从同一毒液中分离出的毒素CM - 9a的序列略有不同（朱伯特和塔尔亚德，《霍佩 - 赛勒氏生理化学杂志》，361 (1980) 425）。差异包括在Ser35和Arg37之间有一个额外的残基（Trp36），以及毒素分子C末端部分的两个残基（Tyr52和Lys50）发生了互换。这些变化改善了与其他弱神经毒素序列的比对。进一步的序列比较表明，WTX是从眼镜蛇毒液中分离出的首例含色氨酸的弱神经毒素。研究发现，WTX能与放射性碘化α - 银环蛇毒素竞争结合来自加州电鳐的膜结合型烟碱乙酰胆碱受体。
