Sericin (inci)

Sericin is a soluble (soluble in propylene glycol or glycerin) glycoprotein derived from natural silkworm extract from silkworms (Bombyx mori).

Note: Natural silk is made up of long chain protein molecules (scleroprotein) the fibroin (70-80 %). It also contains silk bast, the glycoprotein sericin (20-30 %), which has a high content of the amino acid serine. The structure of the natural silk thread is similar to that of human keratin.

Fibroin is a β keratin with a molecular mass of 365,000 kDa. The repeating sequence of amino acids in fibroin is: Gly-Ser-Gly-Ala-Gly-Ala. The amino acid frequency is repeated over long distances. The result is fine, elongated fibrils which aggregate to form a resistant, firm but hardly elastic fibre.

Sericin is used in cosmetic formulations. The protein acts as an antistatic agent (reduces electrostatic charges, e.g. of the hair), smoothing agent (reduces the roughness of the skin and smoothes out irregularities), hair conditioning agent (makes the hair easy to comb, smooth, soft and shiny and gives it volume) and as a skin care agent (keeps the skin in good condition)

For the allergological significance of sericin see "Silk allergy" below