Protein Secondary Structure of Green Lynx Spider Dragline Silk Investigated by Solid-state NMR and X-ray Diffraction
 

Protein Secondary Structure of Green Lynx Spider Dragline Silk Investigated by Solid-state NMR and X-ray Diffraction

Publication date: Available online 29 July 2015
Source:International Journal of Biological Macromolecules</br>
Author(s): Dian Xu, Xiangyan Shi, Forrest Thompson, Warner S. Weber, Qiushi Mou, Jeffery L. Yarger</br>
In this study, the secondary structure of the major ampullate silk from Peucetia viridans (Green Lynx) spiders is characterized by X-ray diffraction and solid-state NMR spectroscopy. From X-ray diffraction measurement, ?-sheet nanocrystallites were observed and found to be highly oriented along the fiber axis, with an orientational order, f _ c ? 0.98. The size of the nanocrystallites was determined to be on average 2.5nm x 3.3nm x 3.8nm. Besides a prominent nanocrystalline region, a partially oriented amorphous region was also observed with an f _ a ? 0.89. Two-dimensional 13C-13C through-space and through-bond solid-state NMR experiments were employed to elucidate structure details of Peucetia viridans silk proteins. It reveals that ?-sheet nanocrystallites constitutes 40.0±1.2% of the protein and are dominated by alanine-rich repetitive motifs. Furthermore, based upon the NMR data, 18±1% of alanine, 60±2% glycine and 54±2% serine are incorporated into helical conformations.
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