Structural Determination of the Tandem Repeat Motif in Samia cynthia ricini Liquid Silk by Solution NMR

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• 作者：Yu Suzuki ; Shuto Kawanishi ; Toshimasa Yamazaki ; Akihiro Aoki ; Hitoshi Saito ; Tetsuo Asakura
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：September 22, 2015
• 年：2015
• 卷：48
• 期：18
• 页码：6574-6579
• 全文大小：410K
• ISSN：1520-5835

文摘

The wild silkworm Samia cynthia ricini produces silk fibroin containing polyalanine sequences. The structure of a typical tandem repeat sequence YGGDGG(A)₁₂GGAG within S. c. ricini silk fibroin in liquid silk was determined by solution NMR. ¹³C, ¹⁵N, and ¹H shifts were assigned from solution NMR spectra for the tandem repeat. TALOS-N was then used to predict the backbone dihedral angles from the chemical shifts. Dihedral angles revealed a well-structured 伪-helix for the polyalanine region and less stable capping motifs for the N- and C-terminal regions. Consistent with this, the amide proton temperature coefficients of the last glycine in the N-terminal region and the first two glycines in the C-terminal region show more positive values than that of a random coil structure. Thus, the 伪-helical structure of the polyalanine region of S. c. ricini liquid silk is stabilized by capping motifs.