Which one of the following proteins gives lustrous shiny appearance to silk fibre?

Silk fibre is primarily composed of two proteins: fibroin and sericin [1]. Fibroin forms the structural core of the fibre, while sericin acts as a gummy, protective coating that binds the fibroin filaments together [1]. Sericin is a water-soluble protein that provides the silk with its characteristic lustrous and shiny appearance. While fibroin's triangular structure contributes to light refraction and shimmering, sericin is specifically recognized for enhancing the shine and providing a smooth, glossy finish to the fibre. In the textile industry, the process of degumming involves removing sericin to reveal the underlying fibroin, but the presence of sericin in raw silk is what provides the initial luster and protective glow [1]. Other options like fibrin (blood clotting), collagen (connective tissue), and nectin (cell adhesion) are unrelated to silk production.

Sources

1. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 9: Agriculture > Production > p. 95