keratin

[ ker-uh-tin ]

noun

1. a fibrous, structural protein that is the principal constituent of hoofs, nails, claws, talons, bills, horn, hair, feathers, etc., and that is found in the outermost layers of skin.

keratin

/ ˈkɛrətɪn /

noun

1. a fibrous protein that occurs in the outer layer of the skin and in hair, nails, feathers, hooves, etc

keratin

/ kĕr′ə-tĭn /

1. Any of a class of tough, fibrous proteins that are the main structural component of hair, nails, horns, feathers, and hooves. Keratins are rich in sulfur-containing amino acids, especially cysteine. Individual keratin molecules are entwined helically around each other in long filaments, which are cross-linked by bonds between sulfur atoms on different chains. The twining and cross-linking produce strength and toughness.

Word History and Origins

Origin of keratin¹

First recorded in 1840–50; kerat- + -in ²

Example Sentences

Light scattering off of microscopic layers of air, the protein keratin and melanin-containing structures called melanosomes creates iridescent feathers’ sheen.

From Science News

Rhino horns are made of keratin, the same protein found in our fingernails.

From The Daily Beast

Keratin is particularly rich in sulphur, and is quite insoluble in cold water.

From Project Gutenberg

Keratin, a substance forming the chief constituent in the hair, nails, and horn of animals.

From Project Gutenberg