Heterogeneous structure of silk fibers from Bombyx mori resolved by 13C solid-state NMR spectroscopy
Heterogeneous structure of silk fibers from Bombyx mori resolved by 13C solid-state NMR spectroscopy
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DOI：
10.1021/ja020244e
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发表时间：
2002-07-31
影响因子：
15
通讯作者：
Ulrich, AS
中科院分区：
文献类型：
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作者：
Asakura, T;Yao, JM;Ulrich, AS
用固态13c核磁共振表征了纺丝前（丝I结构）和纺丝后（丝II结构）的分子构象。我们将天然丝纤维与准结晶cp -部分和合成模型肽（Ala-Gly）15进行了比较，两者都可以通过9 M LiBr透析转化为丝I或通过甲酸处理转化为丝II。我们的研究结果表明，丝II纤维本质上是不均匀的，由β-片、扭曲的β-弯和扭曲的β-片组成。Ala的13c - nmr c - β峰揭示了这种高阶非均质性，表明Ala侧链部分平行，部分面对面，以1:2的比例堆叠。
The molecular conformation of silk fibrion is characterized by solid-state13C NMR before spinning (silk I structure) and after spinning (silk II structure). We compare native silk fibers with the quasi-crystalline Cp-fraction and a synthetic model peptide (Ala-Gly)15, both of which can be converted either into silk I by dialysis from 9 M LiBr or into silk II by treatment with formic acid. Our results demonstrate that silk II fibers are intrinsically heterogeneous, consisting of β-sheets, distorted β-turns, and distorted β-sheets. This higher-order heterogeneity is revealed by the13C-NMR Cβ-peak of Ala, indicating that the Ala side chains are stacked partially in parallel and partially face-to-face, at a ratio of 1:2.