Spider silk research papers

Therefore, it would appear that black widow spiders have replaced FLAG silk, which comprises the spiral capture silk fibers, with scaffolding silk or dragline silk.

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During extrusion, these spidroins undergo changes that alter their conformation and orientation. Several different cloning strategies have been applied to overcome these barriers, including codon optimization of silk genes, specialized growth media and conditions, as well as use of a variety of different host organisms for recombinant silk production Fahnestock and Irwin, ; Schmidt et al.

We have taken a novel approach, combining regenerated silk fibroins with recombinant proteins, to study the material properties of synthetic composite spider silk fibers.

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Spider silk contains large and aggregation-prone proteins spidroins which are produced by sequestering their aggregation-prone regions in micellar structures whose shell is formed by the soluble N-terminal domain NT. Both dragline silk fibers and egg sacs have been studied for their biocompatibility in a few human cell culture systems Allmeling et al.

The specific biological function of the SAG or the molecular contents it synthesizes, stores and spins is unclear.

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In our attempt to enhance the properties of regenerated dragline spider silk, we have supplemented this silk with recombinantly expressed truncated dragline silk fibroins, MaSp1 and MaSp2. Raman spectroscopy studies performed on the glandular contents of the tubuliform gland support this supposition, which demonstrate proteins are stored in a globular conformation with a high degree of alpha helical nature; this differs significantly from the conformations of fibroins stored within the major ampullate gland Lefevre et al.

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For certain silk types, supercontraction may provide an important mechanism to tailor silk properties for synthetic composite spider silks. Studies investigating the effects of reeling speeds demonstrate 3 nm nanocrystals are optimal for producing fibers that have exceptionally high tensile strength. Because PTMs are largely restricted to eukaryotic cells, expression systems equipped with the cellular machinery for PTMs offer benefits to potentially achieving fibroin states that resemble in vivo conditions. Previous biochemical analyses performed by our laboratory have demonstrated that aciniform silks are also constituents of egg case silk in black widow spiders. Natural dragline silk fibers have also been used to culture human primary Schwann cells and demonstrate these cells can adhere and elongate Allmeling et al. These studies have revealed that spider silk is well tolerated and generates little, if any, inflammatory response in the host animal. The interior of fractured regenerated egg case fibers showed a solid core, suggesting that fibroin assembly was not impaired during the spinning process Fig. As a result, only the structural analysis of the silk was performed using nuclear magnetic resonance NMR ; results indicated that the silk structure was not significantly changed by incorporation of spider dragline silk protein. Consistent with this observation, molecular modeling stress-strain simulations predict that 3 nm crystals, which correlate to the natural size found in dragline silk, have higher ultimate strengths and toughness relative to fibers with larger nanocrystal sizes Nova et al. To analyze more precisely the physical properties of transgenic silk, herein we generated transgenic silkworms using the C strain, which expresses the modified spider dragline protein reported previously [20]. Composite silk fibers spun from regenerated major ampullate silk spidroins blended with recombinant proteins Although synthetic silk fibers have been spun from recombinant spider silk proteins, silk filaments have also been reported from dissolving natural dragline silk and re-spinning the solubilized fibroin extract, a process that leads to a material known as regenerated silk. This supports that the C-terminus contributes to enhancing the mechanical properties of the blended fibers. All images were collected at a magnification of X. Even natural dragline silk proteins tend be around kDa, although there are a few, bigger outliers. The major ampullate gland of N.

In addition, we thank Kaitlen Colafrancesco and Coby La Mattina for their critical comments on the book chapter.

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Spider Silk Research Papers