Main Page | See live article | Alphabetical index


Keratin is a protein used by numerous groups of animals as a structural element, and is a classic example of a fibrous protein.

It is the main component of:

Keratin molecules are helical and fibrous, twisting around each other to form strands called intermediate filaments. These proteins contain a high percentage of sulfur-containing amino acids, largely cysteine, which form disulfide bridges between the individual molecules resulting in a fairly rigid structure. Human hair is approximately 14% cysteine.