Engineering of peptide beta-sheet nanotapes
Engineering of peptide beta-sheet nanotapes
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DOI：
10.1039/a701088e
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发表时间：
1997-07-01
影响因子：
--
通讯作者：
Semenov, A
中科院分区：
文献类型：
--
作者：
Aggeli, A;Bell, M;Semenov, A
概述了短寡肽的设计原则，短寡肽将在适当的溶剂中自组装成长的、半柔性的聚合β-片层纳米带。它们的有效性通过对在水中形成纳米带的 11 残基肽 (DN1) 和在甲醇等非水溶剂中形成纳米带的 24 残基肽 (K24) 的实验研究得到证明。对极稀溶液 (μM) 中自组装行为的圆二色性 (CD) 光谱研究揭示了 DN1 中从随机卷曲构象到 β 折叠构象的简单转变，但 K24 的情况更为复杂。 DN1 的结合在浓度达到 40 μM 时非常弱，此时 β-折叠结构中肽的比例突然增加，表明明显的“临界带浓度”。这被证明是由两步自组装过程引起的：第一步是从无规卷曲转变为延伸的β链构象，第二步将该β链添加到不断生长的β折叠中。两种肽均在浓度高于 2 x 10(-3) 体积分数时使其溶剂凝胶化：这些凝胶在溶剂沸点以下都很稳定。对 2-氯乙醇中的 24 个残基肽的凝胶进行流变学测量表明，对于肽体积分数 0.03-0.003，带形成网目尺寸为 10-100 nm 的缠结网络；胶带的持久长度为13纳米或更长，表明聚合物具有中等刚性；这些胶带的厚度约为一个分子。凝胶的机械性能在许多方面与天然生物聚合物（如明胶、肌动蛋白、直链淀粉和琼脂糖）相当。
A set of principles are outlined for the design of short oligopeptides which will self-assemble in appropriate solvents into long, semi-flexible, polymeric beta-sheet nanotapes. Their validity is demonstrated by experimental studies of an 11-residue peptide (DN1) which forms nanotapes in water, and a 24-residue peptide (K24) which forms nanotapes in non-aqueous solvents such as methanol. Circular dichroism (CD) spectroscopy studies of the self-assembly behaviour in very dilute solutions (mu M) reveal a simple transition from a random coil-to-beta-sheet conformation in the case of DN1, but a more complex situation for K24. Association of DN1 is very weak up to a concentration of 40 mu M at which there is a sudden increase in the fraction of peptide in the beta-sheet structure, indicative of an apparent 'critical tape concentration'. This is shown to arise from a two-step self-assembly process: the first step being a transition from a random coil to an extended beta-strand conformation, and the second the addition of this beta-strand to a growing beta-sheet. Both peptides are shown to gel their solvents at concentrations above 2 x 10(-3) volume fraction: these gels are stable up to the boiling point of the solvents. Rheology measurements on gels of the 24-residue peptide in 2-chloroethanol reveal that the tapes form an entangled network with a mesh size of 10-100 nm for peptide volume fractions 0.03-0.003; the persistence length of the tape is 13 nm or greater, indicative of a moderately rigid polymer; the tapes are about a single molecule in thickness. The mechanical properties of the gels in many respects are comparable to those of natural biopolymers such as gelatin, actin, amylose and agarose.