Keratin is a fibrous, sulfur - containing protein manufactured by the body of man and animal and is the basic building block of hair, nails, feathers, hooves, and horns.
Keratiin on kiudjas väävlit sisaldav valk, mida sünteesib nii inim - kui ka loomorganism ning see on karvade, küünte, sulgede, kapjade ja sarvede peamiseks koostisosaks.