Objectives: To isolate a potassium ion channel Kv4.1 inhibitor from centipede venom, and to determine its sequence and structure.
Methods: Ion-exchange chromatography and reversed-phase high-performance liquid chromatography were performed to separate and purify peptide components of centipede venom, and their inhibiting effect on Kv4.1 channel was determined by whole-cell patch clamp recording. The molecular weight of isolated peptide Kv4.1 channel inhibitor was identified with matrix assisted laser desorption ionization-time-of-flight mass spectrometry; its primary sequence was determined by Edman degradation sequencing and two-dimensional mass spectrometry; its structure was established based on iterative thread assembly refinement online analysis.
Results: A peptide SsTx-P2 was separated from centipede venom with the molecular weight of 6122.8, and its primary sequence consists of 53 amino acid residues NH2-ELTWDFVRTCCKLFPDKSECTKACATEFTGGDESRLKDVWPRKLRSGDSRLKD-OH. Peptide SsTx-P2 potently inhibited the current of Kv4.1 channel transiently transfected in HEK293 cell, with 1.0 μmol/L SsTx-P2 suppressing 95% current of Kv4.1 channel. Its structure showed that SsTx-P2 shared a conserved helical structure.
Conclusions: The study has isolated a novel peptide SsTx-P2 from centipede venom, which can potently inhibit the potassium ion channel Kv4.1 and displays structural conservation.
目的: 挖掘蜈蚣毒液中的电压门控钾离子通道Kv4.1多肽抑制剂，确定其一级结构，并对其空间结构进行建模分析。方法: 利用离子交换层析和反相高效液相色谱对蜈蚣毒液的多肽组分进行分离纯化，通过全细胞膜片钳技术鉴定能够抑制Kv4.1通道的多肽；运用基质辅助激光解析电离-飞行时间质谱鉴定多肽的分子量，借助Edman降解测序和二维质谱测序确定多肽的一级结构；基于迭代线程装配细化在线分析建立多肽空间结构模型。结果: 从蜈蚣毒液中分离纯化得到一条能够抑制Kv4.1通道的多肽SsTx-P2，分子量为6122.8，氨基酸序列为NH2-ELTWDFVRTCCKLFPDKSECTKACATEFTGGDESRLKDVWPRKLRSGDSRLKD-OH，其在1.0 μmol/L浓度下能够抑制Kv4.1通道超过95%的电流。空间结构模型显示，多肽SsTx-P2拥有一个保守的螺旋结构。结论: 本文通过分离纯化从蜈蚣毒液中得到一条多肽SsTx-P2，能够强效抑制钾离子通道Kv4.1，其空间结构具有一定的保守性。.
Keywords: Centipede; Kv4.1 channel inhibitor; Peptide; Potassium channel; Structure.