Britannica
Sources used in this answer
How does keratin help make the outer layer of skin tough?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
human skin
Human skin, whose cells are generated continuously by the body, serves as a protective barrier between the inside of the human body and the environment.
Keratin is a tough, insoluble filamentous protein that provides structural integrity to the outermost layer of the skin, known as the stratum corneum. Its ability to make the skin tough and stable is primarily due to its unique chemical composition and structure:12
- Disulfide Bonds: Keratin molecules are stabilized by numerous disulfide bonds formed between cysteine residues. These covalent links create a highly stable, rigid network that resists degradation.134
- Insolubility: Keratin is completely insoluble in water and is resistant to proteolytic enzymes, which prevents the skin from being easily broken down or dissolved.34
- Structural Arrangement: The protein is composed of polypeptide chains that form a dense, packed structure within the cornified cells of the epidermis.14
Together, these properties allow keratin to act as a durable, protective barrier against environmental threats, including chemicals, microbes, and physical wear.23