title: Structural Transition of Bombyx mori Liquid Silk Studied with Vibrational Circular Dichroism Spectroscopy.
abstract: We investigated the structural transition from liquid silk to silk fibers with vibrational circular dichroism spectroscopy. Liquid silk showed a major right-handed optically active band at around 1650 cm(-1) and a minor one at around 1680 cm(-1). The former disappeared over time, while the intensity in the latter increased. With the former wavenumber, liquid silk mainly adopted a random-coil structure. In contrast, the latter may reflect an intermediate structure in the transition. Furthermore, two right-handed bands at around 1630 and 1660 cm(-1) appeared with the disappearance of the major band, and then the wavenumber of the former shifted to around 1620 cm(-1). The shift results from the decrease in the frequency of the CO stretching mode due to the stacking of the β-sheet that comprises fibers. The band at 1660 cm(-1) may reflect another intermediate structure due to its strong correlation with that at 1620 cm(-1) in terms of their temporal change in intensity.
authors.affiliation: Department of Chemistry, Faculty of Science, Tokyo University of Science.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Morisaku
authors.forename: Sho
authors.initials: S
authors.lastname: Arai
authors.forename: Kohzo
authors.initials: K
authors.lastname: Konno
authors.forename: Yu
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Asakura
authors.forename: Hiroharu
authors.initials: H
authors.lastname: Yui
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry*; D002942:Circular Dichroism; D005349:Fibroins / Q000737:chemistry*; D014732:Vibration
chemical_list: D005349:Fibroins