Optical Characterization of Silk Secretions and Fibers

Conformational polymorphism, stability and aggregation in spider dragline silks proteins

“…This intermediate, alike to a molten globule [44,45], could provide compactness [3] without rigid packing of secondary structure; substantial fluctuations of side chains as well as of larger parts of the proteins [23,44,46]. Thus, providing the spider with a structurally complex, storable and transportable protein ready to undergo a transition to a solid fiber.…”

“…␤-sheet structure has been observed in the duct [2,3] and a rheological investigation of dilute native spidroin solutions shows a sudden increase in viscosity at a critical shear rate followed by unstable rheology caused by fiber formation [4] there is no direct evidence for the existence of a favored, strain-sensitive, secondary structure in the protein dope from which the silk thread is formed. In a recent study [5], we observed that the secondary structure changes from the start of the storage ampulla where the conformation was predominantly random coil, to a ␤-sheet/␤-turns structure immediately before the commencement of the spinning duct, suggesting that the preparation for spinning may involve preferential re-arrangement of the protein chains that may facilitate spinning and modulate fiber characteristics.…”

Spider major ampullate silk (drag line): smart composite processing based on imperfect crystals

“…Guided by the early literature, we selected tin as the metal, based both on its apparent effectiveness at weighting and on its rich electron density. Strongly chaotropic solutions are necessary to swell or dissolve silk fibres (Lombardi & Kaplan, 1990;Viney et al, 1994). Consulting the Hofmeister Series, which catalogues the effect of metal salts on the solubility of proteins (Leberman, 1991), led to the choice of chloride as the anion.…”

Dynamic interactions between nematic point defects in the spinning extrusion duct of spiders

“…[7][8][9][10][11] Spider silks, like the majority of high-performance industrial fibers, are spun from a lyotropic nematic liquid crystalline precursor. 2,7,8,12,13 The emergence of this mesophase ͑i.e., intermediate phase͒ is due to the high concentration of rodlike molecules or aggregates in the watery dope solution. A nematic mesophase can flow as a liquid at the same time possessing some degree of orientational order as a crystal.…”