title: Mechanical properties of regenerated Bombyx mori silk fibers and recombinant silk fibers produced by transgenic silkworms.
abstract: Regenerated silk fibroin fibers from the cocoons of silkworm, Bombyx mori, were prepared with hexafluoro solvents, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) or hexafluoroacetone-trihydrate (HFA), as dope solvents and methanol as coagulation solvent. The regenerated fiber prepared from the HFIP solution showed slightly larger tensile strength when the draw ratio is 1:3 than that of native silk fiber, but the strength of the regenerated fiber with draw ratio 1:3 from the HFA solution is much lower than that of native silk fiber. This difference in the tensile strength of the regenerated silk fibers between two dope solvents comes from the difference in the long-range orientation of the crystalline region rather than that of short-range structural environment such as the fraction of beta-sheet structure. The increase in the biodegradation was observed for the regenerated silk fiber compared with native silk fiber. Preparations of regenerated silk fibroin fibers containing spider silk sequences were obtained by mixing silk fibroins and silk-like proteins with characteristic sequences from a spider, Naphila clavipes, to produce drag-line silk in E. coli in the fluoro solvents. A small increase in the tensile strength was obtained by adding 5% (w/w) of the silk-like protein to the silk fibroin. The production of silk fibroin fibers with these spider silk sequences was also performed with transgenic silkworms. Small increase in the tensile strength of the fibers was obtained without significant change in the elongation-at-break.
authors.affiliation: Department of Biotechnology, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan.
authors.forename: Zhenghua
authors.initials: Z
authors.lastname: Zhu
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kikuchi
authors.forename: Katsura
authors.initials: K
authors.lastname: Kojima
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tamura
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kuwabara
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Asakura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D012831:Bombyx / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D005349:Fibroins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010447:Peptide Hydrolases / Q000378:metabolism; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013314:Stress, Mechanical; D013718:Tensile Strength; D014961:X-Ray Diffraction
chemical_list: D011994:Recombinant Proteins; D005349:Fibroins; D010447:Peptide Hydrolases