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首页> 外文期刊>Biochemistry >Synthesis and characterization of a beta-hairpin peptide that represents a 'core module' of bovine pancreatic trypsin inhibitor (BPTI).
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Synthesis and characterization of a beta-hairpin peptide that represents a 'core module' of bovine pancreatic trypsin inhibitor (BPTI).

机译：β-发夹肽的合成和表征，其代表牛胰胰蛋白酶抑制剂（BPTI）的“核心模块”。

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摘要

A new strategy for the design and construction of peptide fragments that can achieve defined, nativelike secondary structure is presented. The strategy is based upon the hypothesis that 'core elements' of a protein, synthesized in a single polypeptide molecule, will favor nativelike structure, and that by incorporating a cross-link, nativelike core structure will dominate the ensemble as the more extended conformations are excluded. 'Core elements' are the elements of packed secondary structure that contain the slowest exchanging backbone amide protons in the native protein. The 'core elements' in bovine pancreatic trypsin inhibitor (BPTI) are the two long strands of antiparallel beta-sheet (residues 18-24 and 29-35) and the small beta-bridge (residues 43-44). To test the design strategy, we synthesized an 'oxidized core module', which contains the antiparallel strands connected by a modified reverse turn (A27 replaced by D), a natural disulfide cross-link at the open end of the hairpin, and N- and C-termini blocking groups. A peptide with identical sequence but lacking the disulfide cross-link at the open end was used as the 'reduced core module' control. The conformational behavior of both peptides was examined using (1)H NMR spectroscopy. Chemical shift dispersion, chemical shift deviation from random coil values, sequential and long-range NOEs, and H/D amide exchange rates were compared for the two peptides. We conclude that the ensemble of oxidized and reduced core module conformations samples both nativelike 4:4 and non-native 3:5 beta-hairpin structure, and that the oxidized module samples nativelike structure for a greater fraction of the time than the reduced module.
机译：提出了一种新的肽段设计和构建策略，可以实现确定的，类似天然的二级结构。该策略基于以下假设：在单个多肽分子中合成的蛋白质的“核心元素”将有利于天然结构，并且通过引入交联，天然结构的核心结构将主导整个集合，因为构象的延伸性更大。排除在外。 “核心元素”是堆积的二级结构的元素，在天然蛋白质中包含最慢的交换骨架酰胺质子。牛胰胰蛋白酶抑制剂（BPTI）中的“核心元素”是两条平行的反平行β-折叠（残基18-24和29-35）和小β-桥（残基43-44）的长链。为了测试设计策略，我们合成了一个“氧化核心模块”，其中包含反平行链，这些反向平行链通过修饰的反向匝（由A27替换为D），发夹开口端的自然二硫键交联和N-和C端封闭基团。具有相同序列但在开放端缺乏二硫键交联的肽被用作“还原核心模块”对照。使用（1）H NMR光谱检查了这两种肽的构象行为。比较了这两种肽的化学位移分散度，与随机线圈值的化学位移偏差，连续和远距离NOE以及H / D酰胺交换率。我们得出的结论是，氧化和还原的核心模块构象的集合会同时采样自然样4：4和非天然3：5β-发夹结构，并且氧化模块对自然样结构的采样时间要比还原的模块长。

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