Self-assembly and gelation properties of α-helix versus β-sheet forming peptides
Self-assembly and gelation properties of α-helix versus β-sheet forming peptides
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DOI：
10.1039/b811288f
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发表时间：
2009-01-01
期刊：
影响因子：
3.4
通讯作者：
Miller, A. F.
中科院分区：
文献类型：
--
作者：
Saiani, A.;Mohammed, A.;Miller, A. F.
我们研究了一组八肽：AEAEAKAK、AEAKAAK、FEFEFKFK和FEFKFEFK的自组装和凝胶性质。基于苯丙氨酸的多肽在溶液中采用β-折叠构象，基于丙氨酸的多肽形成α-螺旋。AEAKAAK在溶液中没有观察到自组装，但发现AEAEAKAK自组装形成了直径类似于6 nm的粗大、坚硬的纤维。这些纤维由两个并排聚集的纤维组成，形成“珍珠项链”的形态。AEAEAKAK在研究的浓度范围内(0~100 mg·ml~(-1))未观察到凝胶化现象。相反，两种基于苯丙氨酸的多肽被发现在溶液中自组装并在初始浓度类似于8mgml(-1)时形成水凝胶。观察到两种多肽的形态相似，对应于相对均匀的致密网络的半柔性纤维，根据浓度的不同，网目尺寸类似于15-30 nm。发现纤维直径类似于4 nm，与文献中发现的模型很好地一致。电子显微镜清楚地表明，这些纤维具有螺旋状或扭曲的结构。透射电子显微镜和原子力显微镜数据的比较突出了底物化学对小肽大分子组装的影响。相比之下，小角中子散射(SANS)方法可以探测水凝胶的形态和结构，而不需要在固体基质上制备样品，从而提供了有关水凝胶在溶液中形态的重要数据。
We have investigated the self-assembly and gelation properties of a set of four octa-peptides: AEAEAKAK, AEAKAEAK, FEFEFKFK and FEFKFEFK. The phenylalanine based peptides adopt beta-sheet conformations in solution and the alanine based peptides form alpha-helices. No self-assembly in solution was observed for AEAKAEAK but AEAEAKAK was found to self-assemble forming thick, rigid fibres with a diameter of similar to 6 nm. These fibres were composed of two fibrils aggregating side by side to form "pearl-necklace" morphologies. No gelation was observed for AEAEAKAK in the concentration range investigated (0 to 100 mg ml(-1)). In contrast, both phenylalanine based peptides were found to self-assemble in solution and to form hydrogels at an initial concentration of similar to 8 mg ml(-1). Similar morphologies were observed for both peptides corresponding to a relatively homogeneous dense network of semi-flexible fibres with a mesh size of similar to 15 to 30 nm depending on the concentration. The fibre diameter was found to be similar to 4 nm in good agreement with models found in the literature. TEM micrographs clearly showed that these fibres have a helicoidal or twisted structure. Comparison of TEM with AFM data highlighted the influence of substrate chemistry on the macromolecular assembly of small peptides. In contrast small angle neutron scattering (SANS) approaches, which allow for the probing of hydrogel morphology and structure without the need for sample preparation on solid substrates, provide vital data on hydrogel morphology in solution.