Pilz Claudia S, Steinem Claudia
Institut für Organische und Biomolekulare Chemie, Georg-August Universität, Tammannstr. 2, 37077, Göttingen, Germany.
Eur Biophys J. 2008 Jul;37(6):1065-71. doi: 10.1007/s00249-008-0298-8. Epub 2008 Mar 18.
An alpha-helical amphipathic peptide with the sequence H2N-(LSSLLSL)3-CONH2 was obtained by solid phase synthesis and a 2,2'-bipyridine was coupled to its N-terminus, which allows complexation of Ni2+. Complexation of the 2,2'-bipyridine residues was proven by UV/Vis spectroscopy. The peptide helices were inserted into lipid bilayers (nano black lipid membranes, nano-BLMs) that suspend the pores of porous alumina substrates with a pore diameter of 60 nm by applying a potential difference. From single channel recordings, we were able to distinguish four distinct conductance states, which we attribute to an increasing number of peptide helices participating in the conducting helix bundle. Addition of Ni2+ in micromolar concentrations altered the conductance behaviour of the formed ion channels in nano-BLMs considerably. The first two conductance states appear much more prominent demonstrating that the complexation of bipyridine by Ni2+ results in a considerable confinement of the observed multiple conductance states. However, the conductance levels were independent of the presence of Ni2+. Moreover, from a detailed analysis of the open lifetimes of the channels, we conclude that the complexation of Ni2+ diminishes the frequency of channel events with larger open times.
通过固相合成获得了序列为H2N-(LSSLLSL)3-CONH2的α-螺旋两亲性肽，并将2,2'-联吡啶偶联到其N端，这使得能够与Ni2+络合。通过紫外/可见光谱法证实了2,2'-联吡啶残基的络合。通过施加电位差，将肽螺旋插入脂质双层（纳米黑色脂质膜，nano-BLMs）中，该脂质双层悬浮在孔径为60 nm的多孔氧化铝基质的孔中。从单通道记录中，我们能够区分出四种不同的电导状态，我们将其归因于参与导电螺旋束的肽螺旋数量增加。加入微摩尔浓度的Ni2+会显著改变纳米黑色脂质膜中形成的离子通道的电导行为。前两个电导状态显得更为突出，表明Ni2+对联吡啶的络合导致观察到的多个电导状态受到相当大的限制。然而，电导水平与Ni2+的存在无关。此外，通过对通道开放寿命的详细分析，我们得出结论，Ni2+的络合降低了具有较大开放时间的通道事件的频率。
