title: Inducing β-sheets formation in synthetic spider silk fibers by aqueous post-spin stretching.
abstract: As a promising biomaterial with numerous potential applications, various types of synthetic spider silk fibers have been produced and studied in an effort to produce man-made fibers with mechanical and physical properties comparable to those of native spider silk. In this study, two recombinant proteins based on Nephila clavipes Major ampullate Spidroin 1 (MaSp1) consensus repeat sequence were expressed and spun into fibers. Mechanical test results showed that fiber spun from the higher molecular weight protein had better overall mechanical properties (70 KD versus 46 KD), whereas postspin stretch treatment in water helped increase fiber tensile strength significantly. Carbon-13 solid-state NMR studies of those fibers further revealed that the postspin stretch in water promoted protein molecule rearrangement and the formation of β-sheets in the polyalanine region of the silk. The rearrangement correlated with improved fiber mechanical properties and indicated that postspin stretch is key to helping the spider silk proteins in the fiber form correct secondary structures, leading to better quality fibers.
authors.affiliation: Department of Molecular Biology, University of Wyoming, Laramie, WY 82070, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: An
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hinman
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Holland
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Yarger
authors.forename: Randolph V
authors.initials: RV
authors.lastname: Lewis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D003001:Cloning, Molecular; D055119:Elastic Modulus; D004548:Elasticity; D004926:Escherichia coli; D005349:Fibroins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D008969:Molecular Sequence Data; D010957:Plasmids; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D047011:Silk / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013112:Spiders / Q000502:physiology; D013314:Stress, Mechanical; D013718:Tensile Strength; D014162:Transfection; D014867:Water
chemical_list: D001672:Biocompatible Materials; D011994:Recombinant Proteins; D047011:Silk; C086087:spidroin 1; D014867:Water; D005349:Fibroins