State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University , Shanghai, 200433, People's Republic of China.
Biomacromolecules. 2013 Jun 10;14(6):1885-92. doi: 10.1021/bm400267m. Epub 2013 May 3.
Synchrotron FTIR (S-FTIR) microspectroscopy was used to monitor both protein secondary structures (conformations) and their orientations in single cocoon silk fibers of the Chinese Tussah silk moth ( Antheraea pernyi ). In addition, to understand further the relationship between structure and properties of single silk fibers, we studied the changes of orientation and content of different secondary structures in single A. pernyi silk fibers when subjected to different strains. The results showed that the content and orientation of β-sheet was almost unchanged for strains from 0 to 0.3. However, the orientation of α-helix and random coil improved progressively with increasing strain, with a parallel decrease in α-helix content and an increase in random coil. This clearly indicates that most of the deformation upon stretching of the single fiber is due to the change of orientation in the amorphous regions coupled with a conversion of some of the α-helix to random coil. These observations provide an explanation for the supercontraction behavior of certain animal silks and are likely to facilitate understanding and optimization of postdrawing used in the conjunction with the wet-spinning of silk fibers from regenerated silk solutions. Thus, our work demonstrates the power of S-FTIR microspectroscopy for studying biopolymers.
同步辐射傅里叶变换红外（S-FTIR）微光谱技术被用于监测中国柞蚕茧丝中单根茧丝中蛋白质二级结构（构象）及其取向。此外，为了进一步了解单根丝纤维结构与性能之间的关系，我们研究了单根 A. pernyi 丝纤维在不同应变下不同二级结构的取向和含量的变化。结果表明，在应变从 0 到 0.3 的范围内，β-折叠的含量和取向几乎不变。然而，α-螺旋和无规卷曲的取向随着应变的增加逐渐改善，α-螺旋的含量平行减少，无规卷曲的含量增加。这清楚地表明，单纤维拉伸时的大部分变形是由于无定形区取向的变化以及部分α-螺旋向无规卷曲的转变所致。这些观察结果为某些动物丝的超收缩行为提供了一种解释，并且可能有助于理解和优化与再生丝溶液纺丝相结合的后拉伸工艺。因此，我们的工作证明了 S-FTIR 微光谱技术在研究生物聚合物方面的强大功能。
