Melanin
Family of biomolecules providing pigments in many organisms.
Melanin is a family of biomolecules organized as oligomers or polymers that provide pigments in many organisms. Produced in specialized cells called melanocytes, melanin pigments are generated through a multistage chemical process known as melanogenesis, involving oxidation of the amino acid tyrosine followed by polymerization.
- types
- Five basic types: eumelanin, pheomelanin, neuromelanin, allomelanin, pyomelanin
- primary_function
- Provides pigments; eumelanin absorbs over 99.9% of UV radiation
- human_epidermal_composition
- Approximately 74% eumelanin, 26% pheomelanin in absence of albinism or hyperpigmentation
- retinal_melanin_change
- Diminishes 2.5-fold between first and ninth decades of life
- associated_cancer
- Melanoma, a cancer of melanocytes
Lore & Background
Melanin is produced in melanocytes through melanogenesis, where tyrosine oxidation leads to polymerization. There are five basic types: eumelanin, pheomelanin, neuromelanin, allomelanin, and pyomelanin. Eumelanin has two forms—DHI-derived (dark brown/black, insoluble) and DHICA-derived (lighter, alkali-soluble)—which often co-polymerize. Pheomelanin, a cysteinated form with polybenzothiazine portions, gives red or yellow tints and is concentrated in lips, nipples, glans of the penis, and vagina. Neuromelanin is found in the brain and binds transition metals such as iron. Allomelanin and pyomelanin are nitrogen-free.
Reader's Guide
Melanin is significant as the primary determinant of human skin color and provides photoprotection by dissipating over 99.9% of absorbed UV radiation. Its levels correlate with UV exposure in the epidermis and with age in the retina, where levels drop 2.5-fold between the first and ninth decades due to oxidative degradation. Studies show lower skin cancer incidence in individuals with more concentrated melanin (darker skin tone). Research into neuromelanin investigates its efficacy in treating neurodegenerative disorders such as Parkinson's disease. The discovery of peptidomelanin and selenomelanin expands understanding of melanin diversity, with selenomelanin offering potential protection against ionizing radiation for space travel.
Did You Know?
- Eumelanin can dissipate over 99.9% of absorbed UV radiation.
- Retinal melanin levels diminish 2.5-fold between the first and ninth decades of life.
- Pheomelanin is concentrated in the lips, nipples, glans of the penis, and vagina.
- Selenomelanin, a selenium analogue of pheomelanin, may provide better protection against ionising radiation.
Frequently Asked Questions
What is Melanin?
Melanin is a family of biomolecule oligomers and polymers that serve as pigments across a wide range of organisms. In humans, these pigment molecules are synthesized inside dedicated cells called melanocytes.
What are the main types of melanin?
Five recognized forms exist: eumelanin, pheomelanin, neuromelanin, allomelanin, and pyomelanin. In a typical human epidermis without albinism or hyperpigmentation, eumelanin accounts for roughly 74% of the pigment while pheomelanin makes up the remaining 26%.
How is melanin actually produced?
The multistage pathway known as melanogenesis begins with the oxidation of the amino acid tyrosine and then proceeds through a series of chemical steps culminating in polymerization into the final pigment molecules.
Why is eumelanin so critical for skin protection?
Eumelanin absorbs more than 99.9% of incoming ultraviolet radiation, making it the body's primary chemical shield against UV-driven DNA damage. This extraordinary absorption capacity is what gives darker skin its superior natural sun protection.
What serious disease is linked to melanocyte dysfunction?
Melanoma is a malignant cancer that arises when melanocytes begin dividing uncontrollably. It represents the most dangerous clinical consequence of dysregulation in the melanin-producing cell lineage.
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