Hydrogelation and Self-Assembly of Fmoc-Tripeptides: Unexpected Influence of Sequence on Self-Assembled Fibril Structure, and Hydrogel Modulus and Anisotropy
Hydrogelation and Self-Assembly of Fmoc-Tripeptides: Unexpected Influence of Sequence on Self-Assembled Fibril Structure, and Hydrogel Modulus and Anisotropy
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DOI：
10.1021/la903678e
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发表时间：
2010-04-06
期刊：
影响因子：
3.9
通讯作者：
Hamley, I. W.
中科院分区：
文献类型：
--
作者：
Cheng, G.;Castelletto, V.;Hamley, I. W.
研究了两种Fmoc三肽[Fmoc = N-（芴基-9-甲氧羰基）]在硼酸盐缓冲溶液和其他碱性溶液中的自组装和水凝胶性质。比较Fmoc-VLK（Boc）与Fmoc-K（Boc）LV，观察到自组装性质的显著差异，两者都含有由N-叔丁氧基碳酸酯（Boc）保护的K。在硼酸盐缓冲液中，前肽形成高度各向异性的原纤维，其显示局部对齐，并且水凝胶显示流动对齐特性。相比之下，Fmoc-K（Boc）LV形成高度支化的原纤维，其产生具有高得多的模量（G' > 10（4）Pa）和用于水凝胶形成的较低浓度的各向同性水凝胶。不同的自组装结构归因于构象差异，如二级结构探针（CD，FTIR，拉曼光谱）和X-射线衍射所揭示的。Fmoc-VLK（Boc）形成具有交叉β X射线衍射图的明确β片层，而Fmoc-KLV（Boc）形成具有多个堆叠片层的无取向组装体。因此，当反转三肽序列时，K和V残基的交换导致自组装结构的实质性差异，这表明了控制水凝胶性质的有希望的方法。
The self-assembly and hydrogelation properties of two Fmoc-tripeptides [Fmoc = N-(fluorenyl-9-methoxycarbonyl)] are investigated, in borate buffer and other basic solutions. A remarkable difference in self-assembly properties is observed comparing Fmoc-VLK(Boc) with Fmoc-K(Boc)LV, both containing K protected by N-epsilon-tert-butyloxycarbonate (Boc). In borate buffer, the former peptide forms highly anisotropic fibrils which show local alignment, and the hydrogels show flow-aligning properties. In contrast, Fmoc-K(Boc)LV forms highly branched fibrils that produce isotropic hydrogels with a much higher modulus (G' > 10(4) Pa), and lower concentration for hydrogel formation. The distinct self-assembled structures are ascribed to conformational differences, as revealed by secondary structure probes (CD, FTIR, Raman spectroscopy) and X-ray diffraction. Fmoc-VLK(Boc) forms well-defined beta-sheets with a cross-beta X-ray diffraction pattern, whereas Fmoc-KLV(Boc) forms unoriented assemblies with multiple stacked sheets. Interchange of the K and V residues when inverting the tripeptide sequence thus leads to substantial differences in self-assembled structures, suggesting a promising approach to control hydrogel properties.