Fischer W B, Pitkeathly M, Wallace B A, Forrest L R, Smith G R, Sansom M S
Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
Biochemistry. 2000 Oct 17;39(41):12708-16. doi: 10.1021/bi001000e.
The putative transmembrane segment of the ion channel forming peptide NB from influenza B was synthesized by standard solid-phase peptide synthesis. Insertion into the planar lipid bilayer revealed ion channel activity with conductance levels of 20, 61, 107, and 142 pS in a 0.5 M KCl buffer solution. In addition, levels at -100 mV show conductances of 251 and 413 pS. A linear current-voltage relation reveals a voltage-independent channel formation. In methanol and in vesicles the peptide appears to adopt an alpha-helical-like structure. Computational models of alpha-helix bundles using N = 4, 5, and 6 NB peptides per bundle revealed water-filled pores after 1 ns of MD simulation in a solvated lipid bilayer. Calculated conductance values [using HOLE (Smart et al. (1997) Biophys. J. 72, 1109-1126)] of ca. 20, 60, and 90 pS, respectively, suggested that the multiple conductance levels seen experimentally must correspond to different degrees of oligomerization of the peptide to form channels.
通过标准固相肽合成法合成了来自乙型流感病毒的离子通道形成肽NB的假定跨膜片段。将其插入平面脂质双分子层后，在0.5M KCl缓冲溶液中显示出离子通道活性，电导水平分别为20、61、107和142 pS。此外，在-100 mV时的电导水平为251和413 pS。线性电流-电压关系表明形成了电压非依赖性通道。在甲醇和囊泡中，该肽似乎呈现出类似α-螺旋的结构。使用每束包含4、5和6个NB肽的α-螺旋束计算模型，在溶剂化脂质双分子层中进行1 ns的分子动力学模拟后显示出充满水的孔。计算得到的电导值[使用HOLE（Smart等人，(1997)《生物物理杂志》72, 1109 - 1126）]分别约为20、60和90 pS，这表明实验中观察到的多个电导水平必定对应于该肽形成通道时不同程度的寡聚化。
