Dissolution of degummed Antheraea yamamai silkworm cocoon

Abstract

Dissolution of Antheraea yamamai silkworm cocoon was carried out in various solvent systems with various dissolving conditions including dissolution salts, salt concentration, dissolving temperature, and time. General chaotropic salt for Bombyx mori silk fibroin does not work for yamamai cocoon. Lithium bromide 9.3 M at 100 o C also does not work to dissolve wild silkworm cocoon. However, 9 M of lithium thiocyanate treatment at 100 o C induced 100% dissolution of wild silkworm cocoon. But it could not be dissolved lower than 60 o C. Like lithium thiocyanate, less than 60 o C treatment with molten calcium nitrate 4 hydrate could not dissolve wild silkworm cocoon. As the dissolution temperature increased up to 100 o C, the solubility of wild one was reached over 90%. SDS-PAGE showed broad tailing stream pattern that means the molecule of wild silk was depolymerized with dissolution temperature and time. From the above results, the best chaotropic salt for A.yamamai silkworm cocoon is calcium nitrate 4 hydrate.