Nephila edulis

Figure 10 shows polarized spectra of two types of silks recorded by Raman spectromicroscopy the dragline silk (the lifeline) of the spider Nephila edulis and the cocoon silk of a wild silkworm Sarnia cynthia ricini. The position of the amide I band at 1,668-1,669 cm-1 for both threads is characteristic of the /i-sheet... 

Figure 10 Polarized spectra obtained by Raman microspectroscopy of (A) the dragline silk of the spider Nephila edulis and (B) the cocoon silk of the silkworm Sarnia cynthia ricini. Adapted with permission from Rousseau et al. [63]. Copyright 2004 American Chemical Society.

Fig. 5. The effect of protein-protein interactions on Nephila edulis major ampullate circular dichroism spectra in solution. A change in secondary structure with increasing concentration is observed. At low concentration (minimal protein-protein interactions) silk proteins appear partially unfolded in solution. At higher concentration (higher protein-protein interactions) silk proteins refold into a helix-like structure, most likely a molten-like globule (from Dicko et al., 2004c). This final molten structure would facilitate local chain rearrangement while preserving the global structure for protein storage and transport. (Copyright 2004 American Chemical Society.)...

Fig. 6. Structural stability of major ampullate silk protein in constrained Nephila edulis. The graph shows a time series of circular dichroism spectra of major ampullate (MA) protein at 1% w/v in distilled water. The spiders prior to dissection were prevented from spinning, but fed and watered for at least 2 weeks. With time, the secondary structure of silk protein is becoming more and more disordered. The arrow indicates increasing time (days). Note that the amino acid composition of the silk protein was similar to that of a native N. edulis spider. Interestingly, silk protein extracted from the constrained spider did not respond to denaturing conditions (detergents, alcohols, pH, and salts Dicko et al, 2004a, 2005).

Hronska, M., Van Beek, J. D., Williamson, P. T., Vollrath, F., and Meier, B. H. (2004). NMR characterization of native liquid spider dragline silk from Nephila edulis. Biomacromolecules 5, 834-839. 

Shao, Z., Hu, X. W., Frische, S., and Vollrath, F. (1999). Heterogeneous morphology of Nephila edulis spider silk and its significance for mechanical properties. Polymer 40, 4709-4711. 

Sirichaisit, J., Brookes, V. L., Young, R.J., and Vollrath, F. (2003). Analysis of structure/ property relationships in silkworm (Bombyx mori) and spider dragline (Nephila edulis) silks using Raman spectroscopy. Biomacromolecules 4, 387-394. 

Vollrath, F., and Knight, D.P. "Structure and function of the silk production pathway in the Spider Nephila edulis". Int. ]. Biol. Macromol. 24(2-3), 243-249 (1999). 

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