The main difference between eumelanin and pheomelanin is that eumelanin is a brown-to-black pigment that is responsible for darker shades of hair, skin, and eyes, whereas pheomelanin is a yellow-to-red pigment that contributes to lighter shades of hair, skin, and eyes.
Eumelanin and pheomelanin are two types of melanin pigments found in humans and other organisms.
Key Areas Covered
1. What is Eumelanin
– Definition, Composition, Features
2. What is Pheomelanin
– Definition, Composition, Features
3. Similarities Between Eumelanin and Pheomelanin
– Outline of Common Features
4. Difference Between Eumelanin and Pheomelanin
– Comparison of Key Differences
Key Terms
Eumelanin, Pigment, Pheomelanin
What is Eumelanin
Eumelanin is a brown-to-black pigment that is responsible for darker shades of hair, skin, and eyes. Eumelanin is a complex polymer derived from the amino acid tyrosine. It is formed through a series of enzymatic reactions involving the key enzyme tyrosinase. The pigment is composed of chains of indole-derived units, which confer its dark coloration. Depending on the specific arrangement and concentration of these units, eumelanin can exhibit two main forms: brown eumelanin and black eumelanin. Brown eumelanin has a more reddish brown color, while black eumelanin appears as deep black.
The production of eumelanin occurs within specialized cells called melanocytes. The synthesis process starts with the conversion of the amino acid tyrosine into a molecule called DOPA by the enzyme tyrosine. Furthermore, enzymatic reactions involving various melanogenic enzymes lead to the formation of eumelanin. Genetic and environmental factors affect the activity of these enzymes and the regulation of eumelanin production.
There are many functions of eumelanin. One such function is protection against ultraviolet radiation. Eumelanin acts as a natural sunscreen by absorbing and dissipating ultraviolet radiation from the sun. It helps to protect the underlying skin cells from damage caused by excessive UV exposure, reducing the risk of sunburn, DNA damage, and skin cancer.
The concentration and distribution of eumelanin in the cells contribute to the variations in human hair and skin color ranging from black to brown. Eumelanin also participates in thermoregulation by influencing the absorption and reflection of sunlight. It also has antioxidant properties. It neutralizes harmful free radicals, which are unstable molecules that cause oxidative damage to cells and tissues.
What is Pheomelanin
Pheomelanin is a yellow-to-red pigment that contributes to lighter shades of hair, skin, and eyes. It has sulfur-containing compounds. Pheomelanin is synthesized by melanocytes, and its production is influenced by genetic factors. People with higher levels of pheomelanin exhibit fairer skin and red or blonde hair, while individuals with higher eumelanin levels have darker skin and hair.
Pheomelanin also has been associated with oxidative stress. The unique chemical structure of pheomelanin makes it prone to generating reactive oxygen species when exposed to UV radiation or other environmental stressors. Studies show that pheomelanin is also involved in regulating cellular and tissue redox balance. Pheomelanin might contribute to cellular responses and influence processes such as inflammation, wound healing, and aging.
Pheomelanin can also act as a metal chelator. It means that it can bind to metal ions and potentially influence their distribution and availability within the body.
Similarities Between Eumelanin and Pheomelanin
- Eumelanin and pheomelanin are responsible for the coloration of various tissues in organisms.
- Both are derived from the amino acid tyrosine.
Difference Between Eumelanin and Pheomelanin
Definition
Eumelanin is a brown-to-black pigment that is responsible for darker shades of hair, skin, and eyes, whereas pheomelanin is a yellow-to-red pigment that contributes to lighter shades of hair, skin, and eyes.
UV Absorption
Eumelanin is more effective in absorbing and dissipating ultraviolet radiation than pheomelanin.
Chemical Composition
Moreover, eumelanin is composed of carbon, hydrogen, nitrogen, and oxygen with little to no sulfur content, whereas pheomelanin contains carbon, hydrogen, nitrogen, oxygen, and sulfur.
Conclusion
The main difference between eumelanin and pheomelanin is that eumelanin is a brown-to-black pigment that is responsible for darker shades of hair, skin, and eyes, whereas pheomelanin is a yellow-to-red pigment that contributes to lighter shades of hair, skin, and eyes.
Reference:
1. “Pheomelanin.” Science Direct.
Image Courtesy:
1. “Pheomelanic pigeon” By Watermelon-lemon – Own work (CC BY-SA 4.0) via Commons Wikimedia
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