Evolution and Application of Coiled Coil Silks from Insects

Kameda, Tsunenori; Walker, Andrew A.; Sutherland, Tara D.

doi:10.1007/978-94-007-7119-2_5

Cited by 3 publications

(2 citation statements)

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“…The silk feedstock is subjected to shear and extensional flow in the fiber spinning process, which initiates its conversion into a crystalline β-sheet structure (silk II) (see Figure ). Similarly, the dominant regions in the high-strength silk structure of spiders ( Araneae ) are oriented spidroin β-sheets formed out of 3 1 -helical or α-helical conformation chains or of random coils present in the glands. − In contrast, the silk proteins of aculeates (stinging Hymenopterans ) are characterized by quite different features in their amino acid sequences . Each silk protein contains alanine-rich domains with a repetition of a heptad sequence motif ( a - b - c - d - e - f - g ) n , in which the positions a and d contain hydrophobic residues and the other positions ( b , c , e , f , and g ) are hydrophilic with a high probability.…”

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confidence: 99%

Transformation of Coiled α-Helices into Cross-β-Sheets Superstructure

et al. 2017

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The fibrous silk produced by bees, wasps, ants, or hornets is known to form a four-strand α-helical coiled coil superstructure. We have succeeded in showing the formation of this coiled coil structure not only in natural fibers, but also in artificial films made of regenerated silk of the hornet Vespa simillima xanthoptera using wide- and small-angle X-ray scatterings and polarized Fourier transform infrared spectroscopy. On the basis of time-resolved simultaneous synchrotron X-ray scattering observations for in situ monitoring of the structural changes in regenerated silk material during tensile deformation, we have shown that the application of tensile force under appropriate conditions induces a transition from the coiled α-helices to a cross-β-sheet superstructure. The four-stranded tertiary superstructure remains unchanged during this process. It has also been shown that the amorphous protein chains in the regenerated silk material are transformed into conventional β-sheet arrangements with varying orientation.

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Section: Introductionmentioning

confidence: 99%

Transformation of Coiled α-Helices into Cross-β-Sheets Superstructure

et al. 2017

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“…13 C CP-MAS NMR spectra of lyophilized hornet silk after dialysis in deionized water at 5 C (DW 5 C), 0.1N ammonia water at 5 C (AW 5 C), deionized water at 45 C (DW 45 C), and 0.1N ammonia water at 45 C (AW 45 C), together with the spectrum of native hornet cocoon for compression.…”

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Influence of pH, temperature, and concentration on stabilization of aqueous hornet silk solution and fabrication of salt‐free materials

Kameda

2014

Biopolymers

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We found that an aqueous solution of silk from cocoons produced by hornet larvae (hornet silk) can be obtained when the solution is adjusted to basic conditions of pH > 9.2. It is known that native hornet cocoons can be dissolved in concentrated aqueous solution of salts, such as lithium bromide (LiBr) and calcium chloride (CaCl2). Upon the removal of these salts from solution by dialysis, solidification, gelation, or sedimentation of hornet silk is known to occur. In the present study, under basic conditions, however, no such solidification occurred, even after salt removal. In this study, ammonia was used for alkalization of solution because it is volatilized during the casting process and pure hornet silk materials can be obtained after drying. The effects of the concentrations of hornet silk and ammonia, as well as dialysis temperature, on preventing gelation during dialysis were investigated. Dialysis conditions that limit the degradation of hornet silk by hydrolysis in alkali solution were identified. Moreover, casting conditions to prepare flexible and transparent hornet silk film from aqueous ammonia solution were optimized. Molecular structural analysis of hornet silk in aqueous ammonia solution and cast film indicated the formation of α-helix conformations.

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