Any of a group of naturally occurring dark pigments, especially the pigment found in skin, hair, fur, and feathers.
(protein) The protein of which hair and nails are composed.
A black pigment found in the pigment-bearing cells of the skin (particularly in the skin of the negro), in the epithelial cells of the external layer of the retina (then called fuscin), in the outer layer of the choroid, and elsewhere. It is supposed to be derived from the decomposition of hemoglobin.
A sulfur-containing fibrous protein constituting the main structural protein of hard epidermal tissues, such as horn, hair, feathers, nails, claws, hoofs, and the like. It is an insoluble substance, and, unlike elastin, is not dissolved even by gastric or pancreatic juice. By decomposition with sulphuric acid it yields leucine and tyrosine plus various other acid-stable amino acids. The amino acid composition varies, but it usually has a high percentage of cystine, which stabilizes and insolubilizes the protein by forming intrachain linkages. A softer form of keratin is present in the epidermis and whalebone. Called also epidermose.
insoluble pigments that account for the color of e.g. skin and scales and feathers
a fibrous scleroprotein that occurs in the outer layer of the skin and in horny tissues such as hair feathers nails and hooves
a dark brown to black pigment occurring in the hair, skin, and iris of the eye in people and animals. It is responsible for tanning of skin exposed to sunlight.
a fibrous protein forming the main structural constituent of hair, feathers, hoofs, claws, horns, etc.
Melanin ( (listen); from Greek: μέλας melas, ) is a broad term for a group of natural pigments found in most organisms. Melanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization.
Keratin () is one of a family of fibrous structural proteins known as scleroproteins. α-Keratin is a type of keratin found in vertebrates.