Question

Protein present in silk fibre is

• A. collagen
• B. fibroin
• C. elastin
• D. casein

Answer 1

Answer: (B)

Silk protein fibroin (a $\beta$-keratin protein) is produced by modified salivary glands of silk worms (silk moth larvae) and by spiders, among other arthropods. Silk is composed of two kinds of very large molecular weight amphoteric colloidal proteins-fibroin and sericin where fibroin constitutes about $75\%$, and sericin $25\%$ of the thread.