Mixture of Rectangular and Staggered Packing Arrangements of Polyalanine Region in Spider Dragline Silk in Dry and Hydrated States As Revealed by 13C NMR and X-ray Diffraction
| Autor: | Tetsuo Asakura, Akihiro Aoki, Akio Nishimura, Yugo Tasei |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Diffraction
Spider Nephila clavata Materials science Polymers and Plastics biology Organic Chemistry 02 engineering and technology Carbon-13 NMR 010402 general chemistry 021001 nanoscience & nanotechnology Antiparallel (biochemistry) biology.organism_classification 01 natural sciences Spectral line 0104 chemical sciences Inorganic Chemistry Crystallography SILK X-ray crystallography Materials Chemistry 0210 nano-technology |
| Zdroj: | Macromolecules. 51:1058-1068 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/acs.macromol.7b02627 |
| Popis: | For the first time, we determined the relative percentages of “rectangular” and “staggered” packing arrangements in the crystalline polyalanine regions with antiparallel β-sheet structure within spider dragline silk fiber from Nephila clavata (NCF) and recombinant silk protein (RSP). The methods used included X-ray diffraction and 13C NMR coupled with selective 13C isotope labeling of the Ala Cβ carbons. From deconvolution analyses of the Ala Cβ peaks in the 13C CP/MAS NMR spectra, the relative percentages of the rectangular arrangements in [3-13C]Ala-NCF were determined to be 49 ± 8% and 40 ± 7% in the dry and hydrated states, respectively, and in [3-13C]Ala-RSP 62 ± 11% and 81 ± 5% in the dry and hydrated states, respectively. Thus, the packing structure changed significantly between the two spider silks and also between the two physical states. The use of NMR was critical in this analysis; from X-ray diffraction patterns alone it would have been difficult to obtain these quantitative data. |
| Databáze: | OpenAIRE |
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