melanin


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melanin

(mĕl`ənĭn), water-insoluble polymer of various compounds derived from the amino acid tyrosinetyrosine
, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein.
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. It is one of two pigments found in human skin and hair and adds brown to skin color; the other pigment is carotenecarotene
, long-chained, unsaturated hydrocarbon found as a pigment in many higher plants, particularly carrots, sweet potatoes, and leafy vegetables. Carotene is thought to assist in trapping light energy for photosynthesis or to aid in chemical reduction.
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, which contributes yellow coloring. The synthesis of melanin reactions is catalyzed by the enzyme tyrosinase; an inherited lack of tyrosinase activity results in one of the forms of albinism. Tyrosinase is found in only one specialized type of cell, the melanocyte, and in this cell melanin is found in membrane-bound bodies called melanosomes. Melanosomes can be transferred from their site of synthesis in the melanocytes to other cell types. The various hues and degrees of pigmentation found in the skin of human beings are directly related to the number, size, and distribution of melanosomes within the melanocytes and other cells. Besides it role in pigmentation, melanin, which absorbs ultraviolet light, plays a protective role when skin is exposed to the damaging rays of the sun (see sunburnsunburn,
inflammation of the skin caused by actinic rays from the sun or artificial sources. Moderate exposure to ultraviolet radiation is followed by a red blush, but severe exposure may result in blisters, pain, and constitutional symptoms.
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; skin cancerskin cancer,
malignant tumor of the skin. The most common types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma. Rarer forms include mycosis fungoides (a type of lymphoma) and Kaposi's sarcoma.
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).

melanin

[′mel·ə·nən]
(biochemistry)
Any of a group of brown or black pigments occurring in plants and animals.

melanin

any of a group of black or dark brown pigments present in the hair, skin, and eyes of man and animals: produced in excess in certain skin diseases and in melanomas
References in periodicals archive ?
A Japanese paper, "Supra-nuclear Melanin Caps Reduce UV-induced DNA Photoproducts in Human Epidermis," (4) shows clearly that, under UV irradiation equivalent to several hours of solar exposure in Long Island (or Barcelona or Naples) in July, the number of photoproducts induced under a tan is only four times less than under a non-tanned skin.
Armed with their initial hypothesis that opsin 3 detects UVA radiation, causing calcium ions to flood the melanocytes and triggering melanin production, the team jumped into experiments.
Vipul Gujrati, first author of the study, explains the principle: Melanin absorbs light very readily even in the infrared spectrum.
class="MsoNormalThe exterior seating area at Melanin in Nairobi.
As we get older, the pigmentproducing melanocytes in our hair follicles gradually lose their ability to create melanin. When there are fewer pigment cells in a hair follicle, that hair will appear more transparent as it grows, appearing grey or silver.
"If you produce red melanin, you will have gold, auburn or red hair, while black melanin produces shades of brown or black."
"Akala ng skin mo yung part na yun laging nagagamit, so mas dadami yung melanin na ipo-produce niya sa part na yon ng skin mo, so mas iitim siya.
In African-American skin, melanin provides an SPF of 13.4, compared to 3.4 in white skin.
Cells were seeded on culture plates and supplemented with different concentrations of samples and [alpha]-melanocyte stimulating hormone ([alpha]-MSH) for 72 h to measure the intracellular tyrosinase activity and quantitate melanin contents.
In vitro, the epidermal melanin unit could be established in tissue-engineered, reconstructed human epidermis.
Inflammatory molecules can also trigger melanin formation, so we are not only inhibiting the tyrosinase activity--at the very heart where melanin is built--but we also interrupt the signaling pathways that trigger melanin formation."
The researchers found that the color change induced by melanin and produced by the biomedical tattoo could be detected with the naked eye and could be quantified optically.