It is used as an additive in skin and hair care products due to its high levels of serine which has excellent moisture preservation characteristics.
As a water-based additive[clarification needed] it is used to provide a protective barrier and silky feel to lotions, soaps, personal lubricants, hair and skincare products.
It also has a unique carbohydrate moiety and a unique repetitive amino acid sequence which give it a high affinity for bonding to adhering proteins resulting in a tightening, anti-wrinkle effect.[how?]
In addition, because of its high molecular weight, it leaves a substantive semi-occlusive film that persists even after washing, and can increase the skins permeability.
[clarification needed] Predominant composition of silk amino acids (by weight*): [1][verification needed] Due to its proteinous nature, sericin is susceptible to the action of proteolytic enzymes, making it digestible; and because of properties like its gelling ability, moisture retention capacity and skin adhesion, it has numerous medical, pharmaceutical and cosmetic applications.