Peptoid oligomers with α-chiral, aromatic side chains:: Effects of chain length on secondary structure
Peptoid oligomers with α-chiral, aromatic side chains:: Effects of chain length on secondary structure
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DOI：
10.1021/ja003153v
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发表时间：
2001-04-04
影响因子：
15
通讯作者：
Barron, AE
中科院分区：
文献类型：
--
作者：
Wu, CW;Sanborn, TJ;Barron, AE
具有α-手性芳族侧链的低聚N-取代的甘氨酸或“类肽”可在有机或水溶液中采用表螺旋，尽管它们缺乏主链手性并且它们不能形成链内氢键。螺旋排序似乎是稳定的空间位阻冲突，以及通过骨架羰基和π云的芳环侧链之间的静电排斥避免。有趣的是，这些类肽螺旋表现出强烈的圆二色性（CD）光谱，非常类似于肽α-螺旋。在这里，我们利用CD系统地研究了寡聚体长度，浓度和温度对有机可溶性类肽同源寡聚体的手性二级结构的影响，其长度范围为3至20个（R）-N-（1 -苯乙基）甘氨酸（Nrpe）单体。我们发现，一个显着的CD光谱特征的演变发生Nrpe低聚物之间的4和12个残基的长度，我们归因于一个链长度依赖的人口交替结构的构象具有顺式与反式酰胺键。在13和20个单体长度之间的低聚物的CD光谱中没有观察到显著的变化，这表明形成稳定的聚（Nrpe）螺旋的最小链长约为13个残基。此外，没有观察到Nrpe六聚体的圆二色性对浓度的依赖性，提供了这些螺旋在溶液中保持单体的证据。根据这些新的数据，我们讨论了链长相关的因素，稳定有机可溶性类肽螺旋这一类，这是很重要的螺旋，仿生类肽共享这个结构基序的设计。
Oligomeric N-substituted glycines or "peptoids" with alpha -chiral, aromatic side chains can adopt table helices in organic or aqueous solution, despite their lack of backbone chirality and their inability to form intrachain hydrogen bonds. Helical ordering appears to be stabilized by avoidance of steric clash as well as by electrostatic repulsion between backbone carbonyls and pi clouds of aromatic rings in the side chains. Interestingly, these peptoid helices exhibit intense circular dichroism (CD) spectra that closely resemble those of peptide alpha -helices. Here, we have utilized CD to systematically study the effects of oligomer length, concentration, and temperature on the chiral secondary structure of organosoluble peptoid homooligomers ranging from 3 to 20 (R)-N-(1 -phenylethyl)glycine (Nrpe) monomers in length. We find that a striking evolution in CD spectral features occurs for Nrpe oligomers between 4 and 12 residues in length, which we attribute to a chain length-dependent population of alternate structured conformers having cis versus trans amide bonds. No significant changes are observed in CD spectra of oligomers between 13 and 20 monomers in length, suggesting a minimal chain length of about 13 residues for the formation of stable poly(Nrpe) helices. Moreover, no dependence of circular dichroism on concentration is observed for an Nrpe hexamer, providing evidence that these helices remain monomeric in solution. In light of these new data, we discuss chain length-related factors that stabilize organosoluble peptoid helices of this class, which are important for the design of helical, biomimetic peptoids sharing this structural motif.