Structural Analysis of Bombyx mori Silk Fibroin Peptides with Formic Acid Treatment Using High-Resolution Solid-State 13C NMR Spectroscopy
详细信息 查看全文
- 作者：Juming Yao ; Kosuke Ohgo ; Rena Sugino ; Raghuvansh Kishore ; and Tetsuo Asakura
- 刊名：Biomacromolecules
- 出版年：2004
- 出版时间：September 2004
- 年：2004
- 卷：5
- 期：5
- 页码：1763 - 1769
- 全文大小：141K
- 年卷期：v.5,no.5(September 2004)
- ISSN：1526-4602
文摘
Bombyx mori silk fibroin fiber is a fibrous protein produced by the silkworm at room temperature and froman aqueous solution whose primary structure is highly repetitive. In this study we analyzed the structuralcharacteristics of native peptides, derived from B. mori silk fibroin, with formic acid treatment using high-resolution solid-state 13C NMR. We establish that the Ser residue bearing a short polar side chain has theability to stabilize the conformation formed in the model peptides due to its ability to form intermolecularhydrogen bonds involving its hydroxyl group as a donor and the carbonyl groups of other residues as acceptors.On the other hand, insertion of Tyr residue in the basic (AG)n and (AGSGAG)n sequence motifs usuallyexhibited disruptive effects on the preferred conformations. Moreover, the environmental effect wasinvestigated by mixing the native Cp fraction with the model peptides, showing that there is no significantstructural difference on the Ser-containing peptides, while structural transformation was observed on thepeptides containing the GAAS unit. This may be attributed to the fact that the Cp fraction promotes theformation of an antiparallel 
-sheet in the Ala-Ala unit. Such periodically disrupted ordered structures inthe semicrystalline region of B. mori silk fibroin may be critical not only for facilitating the conformationaltransformation from silk I to silk II structural form but also for having some correlation with the uniqueproperties of the silk materials.
-sheet in the Ala-Ala unit. Such periodically disrupted ordered structures inthe semicrystalline region of B. mori silk fibroin may be critical not only for facilitating the conformationaltransformation from silk I to silk II structural form but also for having some correlation with the uniqueproperties of the silk materials.