title: Insight into the structure of single Antheraea pernyi silkworm fibers using synchrotron FTIR microspectroscopy.
abstract: 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.
authors.affiliation: 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.
authors.forename: Shengjie
authors.initials: S
authors.lastname: Ling
authors.forename: Zeming
authors.initials: Z
authors.lastname: Qi
authors.forename: David P
authors.initials: DP
authors.lastname: Knight
authors.forename: Yufang
authors.initials: Y
authors.lastname: Huang
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.forename: Huan
authors.initials: H
authors.lastname: Zhou
authors.forename: Zhengzhong
authors.initials: Z
authors.lastname: Shao
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D017356:Synchrotrons; D013718:Tensile Strength