title: Structural evolution of regenerated silk fibroin under shear: combined wide- and small-angle x-ray scattering experiments using synchrotron radiation.
abstract: The structural evolution of regenerated Bombyx mori silk fibroin during shearing with a Couette cell has been studied in situ by synchrotron radiation small- and wide-angle x-ray scattering techniques. An elongation of fibroin molecules was observed with increasing shear rate, followed by an aggregation phase. The aggregates were found to be amorphous with beta-conformation according to infrared spectroscopy. Scanning x-ray microdiffraction with a 5 microm beam on aggregated material, which had solidified in air, showed silk II reflections and a material with equatorial reflections close to the silk I structure reflections, but with strong differences in reflection intensities. This silk I type material shows up to two low-angle peaks suggesting the presence of water molecules that might be intercalated between hydrogen-bonded sheets.
authors.affiliation: European Molecular Biology Laboratory, Hamburg Outstation, Notkestrasse 85, D-22603 Hamburg, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Rössle
authors.forename: Pierre
authors.initials: P
authors.lastname: Panine
authors.forename: Volker S
authors.initials: VS
authors.lastname: Urban
authors.forename: Christian
authors.initials: C
authors.lastname: Riekel
mesh_terms: D005349:Fibroins / Q000737:chemistry* / Q000528:radiation effects*; D019476:Insect Proteins / Q000737:chemistry* / Q000528:radiation effects; D046911:Macromolecular Substances; D008970:Molecular Weight; D011487:Protein Conformation; D047011:Silk; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013314:Stress, Mechanical; D017356:Synchrotrons; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D019476:Insect Proteins; D046911:Macromolecular Substances; D047011:Silk; D005349:Fibroins