A repeated β-turn structure in poly(Ala-Gly) as a model for silk I of Bombyx mori silk fibroin studied with two-dimensional spin-diffusion NMR under off magic angle spinning and rotational echo double resonance
A repeated β-turn structure in poly(Ala-Gly) as a model for silk I of Bombyx mori silk fibroin studied with two-dimensional spin-diffusion NMR under off magic angle spinning and rotational echo double resonance
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DOI：
10.1006/jmbi.2000.4394
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发表时间：
2001-02-16
影响因子：
5.6
通讯作者：
Komatsu, K
中科院分区：
文献类型：
--
作者：
Asakura, T;Ashida, J;Komatsu, K
家蚕丝素蛋白是在纺丝过程前常见的一种晶型丝素蛋白的结构，它是通过结合脱魔角纺丝下的二维自旋扩散核磁共振、旋转回波双共振(REDOR)、X-射线衍射分析和C-13核磁共振化学位移的数据提出的。我们使用序列模型肽(Ala-Gly)(15)来代替具有丝素I结构的家蚕丝素蛋白。序列模型肽在9M溴化锂溶液中溶解后，经水透析后，结构鉴定为丝素I。此外，在这些核磁共振实验中，C-13或N-15标记中心可以通过固相合成法很容易地引入到(Ala-Gly)(15)中的任何位置。测得具有丝素I结构的(Ala-Gly)(15)对丙氨酸和甘氨酸残基的扭转角分别为(-60(+/-5)度，130(+/-5)度)和(70(+/-5)度，30(+/-5)度)。通过测定组成分子内氢键的氮原子和碳原子之间的原子间距离，从REDOR核磁共振中证实了沿着链形成了分子内氢键。这种结构被命名为重复的贝塔转折II型结构。(C)2001年学术出版社。
The structure of a crystalline form of Bombyx mori silk fibroin, commonly found before the spinning process (known as silk I), was proposed by combining data obtained from two-dimensional spin-diffusion nuclear magnetic resonance under off magic angle spinning, rotational-echo double-resonance (REDOR), previously reported X-ray diffraction analyses and C-13 NMR chemical shifts. Instead of B. mori silk fibroin with silk I structure, we used the sequential model peptide (Ala-Gly)(15). The structure of the sequential model peptide is characterized as silk I after dissolving the peptide in 9 M LiBr and then dialyzing against water. Moreover, C-13 or N-15-labeled sites may be introduced easily at any position in (Ala-Gly)(15) by the solid phase synthesis method for these NMR experiments. The torsional angles of (Ala-Gly)(15) with silk I structure were determined as (-60(+/-5)degrees, 130(+/-5)degrees) and (70(+/-5)degrees, 30(+/-5)degrees) for Ala and Gly residues, respectively. The formation of the intra-molecular hydrogen bonding along the chain was confirmed from REDOR NMR by determination of the inter-atomic distance between the nitrogen and carbon atoms comprising the intra-molecular hydrogen bonding. The structure is named a repeated beta -turn type II-like structure. (C) 2001 Academic Press.