Literally meaning: “protein of horn”
Origin: Anc Greek
κέρας/keras(=horn) > (genitive): κέρατος/keratos
The word appeared in literature around 1849 but the first attempt to extract keratins was by John Hoffmeier in 1905.
Keratins is a group of insoluble and tough fibrous proteins that are the main structural component in skin, nails, hair, horns, feathers, hooves and teeth. Keratins are rich in sulfur-containing aminoacids such as cysteine.