Conformation states of gramicidin A along the pathway to the formation of channels in model membranes determined by 2D NMR and circular dichroism spectroscopy.
Conformation states of gramicidin A along the pathway to the formation of channels in model membranes determined by 2D NMR and circular dichroism spectroscopy.
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通过 2D NMR 和圆二色光谱测定短杆菌肽 A 沿模型膜通道形成途径的构象状态。
作者：
N. Abdul;J. F. Hinton
掺入SDS（十二烷基硫酸钠）胶束中的短杆菌肽A作为右手的N-至-N-末端β 6.3螺旋二聚体存在[Lomize，A. L.，Orechov，V. Yu.，& Arseniev，A.S.（1992）Bioorg.基姆18，182-189]。在实现短杆菌肽A在SDS胶束中的离子通道状态的掺入过程中，在加入到水/胶束溶液之前，使用三氟乙醇（TFE）来溶解疏水肽。短杆菌肽A在SDS胶束中形成离子通道的构象转变，在TFE和10%TFE/水中，已经使用2D NMR和CD光谱进行了研究。在纯TFE中，短杆菌肽A被发现是单体的，并且可能存在于至少三种不同形式的快速相互转化的构象异构体的平衡中，这些构象异构体被认为是左手和/或右手α和β 4.4螺旋。结果发现，这些构象之间的相互转换减慢，在55%的TFE明显的观察到至少三个不同的组的d α N COSY峰，虽然CD给出了一个净光谱类似于纯TFE。在10%TFE中短杆菌肽A自发形成沉淀。沉淀的物质被分离并溶解在二氧六环中，其中短杆菌肽构象体经历非常缓慢的相互转化，并且可以通过NMR表征。在10%TFE中发现至少七种不同的短杆菌肽A构象。其中四种是与先前在乙醇中发现的相同类型的双螺旋（即，对称的左手平行β 5.6双螺旋、不对称的左手平行β 5.6双螺旋、对称的左手反平行β 5.6双螺旋、对称的右手平行β 5.6双螺旋）;第五个可能是对称的右手反平行β 5.6双螺旋。也有证据表明存在至少一种形式的单体物质。先前观察到的溶剂历史依赖性的通道掺入的容易程度可以解释为存在几个不同的折叠通道形成的途径。为了验证这一建议，短杆菌肽A在10%DMSO和10%甲醇中的构象进行了研究。在前一种环境中，主要形式是一个无规线圈与少数人口的双链螺旋，而在后者中，NMR光谱表明存在相同的双螺旋构象，发现在纯甲醇。
Gramicidin A incorporated into SDS (sodium dodecyl sulfate) micelles exists as a right-handed, N-to-N-terminal beta 6.3 helical dimer [Lomize, A. L., Orechov, V. Yu., & Arseniev, A.S. (1992) Bioorg. Khim. 18, 182-189]. In the incorporation procedure to achieve the ion channel state of gramicidin A in SDS micelles, trifluoroethanol (TFE) is used to solubilize the hydrophobic peptide before addition to the aqueous/micelle solution. The conformational transition of gramicidin A to form ion channels in SDS micelles, i.e., in TFE and 10% TFE/water, has been investigated using 2D NMR and CD spectroscopy. In neat TFE, gramicidin A was found to be monomeric and may possibly exist in an equilibrium of rapidly interconverting conformers of at least three different forms believed to be left- and/or right-handed alpha and beta 4.4 helices. It was found that the interconversion between these conformers was slowed down in 55% TFE as evident by the observation of at least three different sets of d alpha N COSY peaks although CD gave a net spectrum similar to that in neat TFE. In 10% TFE gramicidin A spontaneously forms a precipitate. The precipitated species were isolated and solubilized in dioxane where gramicidin conformers undergo very slow interconversion and could be characterized by NMR. At least seven different gramicidin A conformations were found in 10% TFE. Four of thes are the same types of double helices as previously found in ethanol (i.e., a symmetric left-handed parallel beta 5.6 double helix, an unsymmetric left-handed parallel beta 5.6 double helix, a symmetric left-handed antiparallel beta 5.6 double helix, a symmetric right-handed parallel beta 5.6 double helix); the fifth is possibly a symmetric right-handed antiparallel beta 5.6 double helix. There is also evidence for the presence of at least one form of monomeric species. Previous observation on the solvent history dependence in the ease of channel incorporation may be explained by the presence of several different folding pathways to channel formation. To test this proposal, the conformation of gramicidin A in 10% DMSO and 10% methanol was studied. In the former environment, the major form was a random coil with a minor population of double-stranded helices, while in the latter, NMR spectra indicate the presence of the same double-helical conformers as found in neat methanol.
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短杆菌肽的单通道特性没有显示出溶剂历史依赖性。
影响因子：
3.4
作者：
Sawyer,DB;Koeppe2nd,RE;Andersen,OS
通讯作者：
Andersen,OS
DOI：
10.1146/annurev.bb.20.060191.002511
发表时间：
1991
期刊：
Annual review of biophysics and biophysical chemistry
影响因子：
--
作者：
Dyson Hj;P. Wright
通讯作者：
Dyson Hj;P. Wright
短杆菌肽通道中电导异质性的诱导。
影响因子：
2.9
作者：
Sawyer,DB;Koeppe2nd,RE;Andersen,OS
通讯作者：
Andersen,OS
影响因子：
56.9
作者：
KETCHEM, RR;HU, W;CROSS, TA
通讯作者：
CROSS, TA
影响因子：
5.6
作者：
PASCAL, SM;CROSS, TA
通讯作者：
CROSS, TA