Correlation of the β-sheet crystal size in silk fibers with the protein amino acid sequence.

Low voltage transmission electron microscopy (LVTEM) and wide angle X-ray scattering (WAXS) are used to independently determine the size of the β-sheet crystalline regions in Bombyx mori silk fibers. The peak in the size distributions of the major and minor axes of the anisotropic crystallites measured from the LVTEM images compare well with the average sizes as determined by Scherrer analysis of the X-ray fiber diagrams. These values are then discussed in the context of the B. mori fibroin heavy chain amino acid sequence, and the underlying mechanism for the organism's control on fiber crystallite size, and therefore mechanical properties, is proposed.

[1]  C. Riekel,et al.  Nanofibrillar Structure and Molecular Mobility in Spider Dragline Silk , 2005 .

[2]  D. Martin,et al.  Morphology and primary crystal structure of a silk‐like protein polymer synthesized by genetically engineered Escherichia coli bacteria , 1994, Biopolymers.

[3]  R. Fraser,et al.  THE FINE STRUCTURE OF SILK FIBROIN , 1967, The Journal of cell biology.

[4]  Yuru Shen,et al.  Microstructural Characterization of Bombyx mori Silk Fibers , 1998 .

[5]  Lawrence F. Drummy,et al.  Regenerated silk fiber wet spinning from an ionic liquid solution , 2005 .

[6]  L. Jelinski,et al.  Small-Angle X-ray Scattering of Spider Dragline Silk , 1997 .

[7]  Laurence Besseau,et al.  Liquid crystalline assemblies of collagen in bone and in vitro systems. , 2003, Journal of biomechanics.

[8]  Oskar Liivak,et al.  Artificial Spinning of Spider Silk , 1998 .

[9]  Y. Termonia.  Molecular modeling of spider silk elasticity , 1994 .

[10]  F Vollrath,et al.  Predicting the mechanical properties of spider silk as a model nanostructured polymer , 2005, The European physical journal. E, Soft matter.

[11]  Fritz Vollrath,et al.  Materials: Surprising strength of silkworm silk , 2002, Nature.

[12]  R. Naik,et al.  Thermally Induced α-Helix to β-Sheet Transition in Regenerated Silk Fibers and Films , 2005 .

[13]  David T. Grubb,et al.  Fiber Morphology of Spider Silk: The Effects of Tensile Deformation , 1997 .

[14]  C. Viney,et al.  Non-periodic lattice crystals in the hierarchical microstructure of spider (major ampullate) silk. , 1997, Biopolymers.

[15]  F. Vollrath,et al.  Biological liquid crystal elastomers. , 2002, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[16]  D A Parry,et al.  The molecular structure of reptilian keratin. , 1996, International journal of biological macromolecules.

[17]  Satish Kumar,et al.  Electron beam damage in high temperature polymers , 1990 .

[18]  A. Hitchcock,et al.  Quantitative mapping of the orientation of fibroin beta-sheets in B. mori cocoon fibers by scanning transmission X-ray microscopy. , 2006, Biomacromolecules.

[19]  Frische,et al.  Elongate cavities and skin–core structure in Nephila spider silk observed by electron microscopy , 1998 .

[20]  David C. Martin,et al.  Low-voltage electron microscopy of polymer and organic molecular thin films. , 2004, Ultramicroscopy.

[21]  Fumio Arisaka,et al.  Silk Fibroin of Bombyx mori Is Secreted, Assembling a High Molecular Mass Elementary Unit Consisting of H-chain, L-chain, and P25, with a 6:6:1 Molar Ratio* , 2000, The Journal of Biological Chemistry.

[22]  M. Kitagawa,et al.  Mechanical properties of dragline and capture thread for the spider Nephila clavata , 1997 .

[23]  M. A. Johnson,et al.  Finite element modeling of banded structures in Bombyx mori silk fibres. , 1999, International journal of biological macromolecules.

[24]  P. Yager,et al.  Comparative Structural Characterization of Naturally- and Synthetically-Spun Fibers of Bombyx mori Fibroin , 1998 .

[25]  Y. H. Park,et al.  Wet spinning of silk polymer. II. Effect of drawing on the structural characteristics and properties of filament. , 2004, International journal of biological macromolecules.

[26]  E. Thomas,et al.  Antiphase boundaries and ordering defects in syndiotactic polystyrene crystals , 1990 .

[27]  B. Lotz,et al.  Twisted single crystals of Bombyx mori silk fibroin and related model polypeptides with beta structure. A correlation with the twist of the beta sheets in globular proteins. , 1982, Journal of molecular biology.

[28]  J. Warwicker.  Comparative studies of fibroins. II. The crystal structures of various fibroins. , 1960, Journal of molecular biology.

[29]  Y. Termonia,et al.  Nylons from Nature: Synthetic Analogs to Spider Silk , 1998 .

[30]  C. Viney,et al.  A Non-Periodic Lattice Model for Crystals in Nephila clavipes Major Ampullate Silk , 1995 .

[31]  R. E. Marsh,et al.  An investigation of the structure of silk fibroin. , 1955, Biochimica et biophysica acta.

[32]  F. Vollrath,et al.  Amyloidogenic nature of spider silk. , 2002, European journal of biochemistry.

[33]  Y. Takahashi,et al.  Structure refinement and diffuse streak scattering of silk (Bombyx mori). , 1999, International journal of biological macromolecules.

[34]  M. Jacquet,et al.  Silk fibroin: Structural implications of a remarkable amino acid sequence , 2001, Proteins.

[35]  W. W. Adams,et al.  Aspects of the Morphology of the Silk of Bombyx Mori , 1996 .

[36]  Steven Arcidiacono,et al.  Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells , 2002, Science.

[37]  I. Um,et al.  Wet spinning of silk polymer. I. Effect of coagulation conditions on the morphological feature of filament. , 2004, International journal of biological macromolecules.

[38]  J. Hinnie,et al.  The primary filament of bovine elastin. , 1978, Journal of ultrastructure research.