Reversibility of the Denaturation of Silk Fibroin

Abstract

SILK, as it occurs in the silk-glands of the silkworm (Bombyx mori), consists of two distinct protein systems, and, during the spinning by the worm of the double filament which serves as a building material for the cocoon, these two systems are forced through small orifices in a manner such that they respectively produce a central core or medulla of fibrous material and an outer layer or cortex of gum-like substance. The cortical protein material (sericin) is readily dispersed by hot solutions of soap or mild alkali, while the protein material (fibroin) forming the core of the filament is insoluble in water and is resistant to relatively strong chemical reagents; it is these properties of the extruded filament that partly account for its use as a textile fibre.