Fibroin

Fibroin is an insoluble protein present in silk produced by numerous insects, such as the larvae of Bombyx mori, and other moth genera such as Antheraea, Cricula, Samia and Gonometa.

[1][2][3] Silk fibroin is considered a β-keratin related to proteins that form hair, skin, nails and connective tissues.

In the fibroin β-sheet there are specific residues that are preserved in the N-terminal domain in order to prevent premature sheet formation at a neutral pH.

By preventing the premature formation, the electrostatic repulsions help ensure that the β-sheet is formed correctly which will allow for fibroin to function properly.

This popularity stems from the discovery that silk fibroin (particularly from Bombyx mori) can be redissolved in chaotropic salt solutions such as calcium chloride or lithium bromide.

[7][8] This process yields an aqueous solution similar to the form found in the silkworm's gland, which can then be used to create various types of materials.