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Selenium in biology. Selenocysteine is the main organic molecule involving selenium in humans. Selenium is an essential micronutrient for animals, though it is toxic in large doses. In plants, it sometimes occurs in toxic amounts as forage, e.g. locoweed. Selenium is a component of the amino acids selenocysteine and selenomethionine.
The selenium cycle is a biological cycle of selenium similar to the cycles of carbon, nitrogen, and sulfur. Within the cycle, there are organisms which reduce the most oxidized form of the element and different organisms complete the cycle by oxidizing the reduced element to the initial state. In the selenium cycle it has been found that ...
Selenium is a chemical element; it has the symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elemental state or as pure ore compounds in Earth's crust.
Selenium, which is an essential element for animals and prokaryotes and is a beneficial element for many plants, is the least-common of all the elements essential to life. [3] [61] Selenium acts as the catalytic center of several antioxidant enzymes, such as glutathione peroxidase, [10] and plays a wide variety of other biological roles.
Selenium deficiency occurs when an organism lacks the required levels of selenium, a critical nutrient in many species.Deficiency, although relatively rare in healthy well-nourished individuals, [1] can have significant negative results, [2] affecting the health of the heart and the nervous system; contributing to depression, anxiety, and dementia; and interfering with reproduction and gestation.
Selenocysteine (symbol Sec or U, [ 4] in older publications also as Se-Cys) [ 5] is the 21st proteinogenic amino acid. Selenoproteins contain selenocysteine residues. Selenocysteine is an analogue of the more common cysteine with selenium in place of the sulfur . Selenocysteine is present in several enzymes (for example glutathione peroxidases ...
Selenate is the form required by organisms that need selenium as a micronutrient. These organisms have the ability to acquire, metabolize and excrete selenium. [ 7 ] The level at which selenium becomes toxic varies from species to species and is related to other environmental factors like pH and alkalinity that influence the concentration of ...
gladyshevlab .bwh .harvard .edu. Vadim N. Gladyshev is a professor of medicine at Brigham and Women's Hospital, [1] Harvard Medical School, who specializes in antioxidant biology. He is known for his characterization of the human selenoproteome. [2] He is also known for his work on the effects of aging in humans.