What is the chemical composition of silk?

Silk is a proteinaceous fiber and contains the protein fibroin. Fibroin is a less complex protein as compared to the keratin found in wool. The composition of fibroin includes: at least 17 amino acids of which alanine, serine, glycine and tyrosine account for 90%. Sericin is the gummy substance that is present between the filament that holds them together. However, this substance is removed during the silk processing by the method of degumming.

Carboxy and amino are two reactive groups present in silk. The fibroin protein chain has hydrogen bonds which imparts a high degree of crystallinity and strength to silk.