title: Reproducing natural spider silks' copolymer behavior in synthetic silk mimics.
abstract: Dragline silk from orb-weaving spiders is a copolymer of two large proteins, major ampullate spidroin 1 (MaSp1) and 2 (MaSp2). The ratio of these proteins is known to have a large variation across different species of orb-weaving spiders. NMR results from gland material of two different species of spiders,  N. clavipes  and  A. aurantia , indicates that MaSp1 proteins are more easily formed into β-sheet nanostructures, while MaSp2 proteins form random coil and helical structures. To test if this behavior of natural silk proteins could be reproduced by recombinantly produced spider silk mimic protein, recombinant MaSp1/MaSp2 mixed fibers as well as chimeric silk fibers from MaSp1 and MaSp2 sequences in a single protein were produced based on the variable ratio and conserved motifs of MaSp1 and MaSp2 in native silk fiber. Mechanical properties, solid-state NMR, and XRD results of tested synthetic fibers indicate the differing roles of MaSp1 and MaSp2 in the fiber and verify the importance of postspin stretching treatment in helping the fiber to form the proper spatial structure.
authors.affiliation: Department of Molecular Biology, University of Wyoming, 1000 East University Avenue, Laramie, Wyoming 82070, United States. orvyan@gmail.com
authors.forename: Bo
authors.initials: B
authors.lastname: An
authors.forename: Janelle E
authors.initials: JE
authors.lastname: Jenkins
authors.forename: Sujatha
authors.initials: S
authors.lastname: Sampath
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Holland
authors.forename: Mike
authors.initials: M
authors.lastname: Hinman
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Yarger
authors.forename: Randolph
authors.initials: R
authors.lastname: Lewis
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D040761:Biomimetic Materials / Q000737:chemistry*; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005349:Fibroins / Q000737:chemistry* / Q000235:genetics; D015870:Gene Expression; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011108:Polymers / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D017422:Sequence Analysis, DNA; D047011:Silk / Q000138:chemical synthesis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013112:Spiders / Q000737:chemistry / Q000235:genetics; D014961:X-Ray Diffraction
chemical_list: D011108:Polymers; D011994:Recombinant Proteins; D047011:Silk; C086087:spidroin 1; C076815:spidroin 2; D005349:Fibroins