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phenylalanine

phenylalanine (fĕn´əlăl´ənēn´), organic compound, one of the 22 α-amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein. It is one of several essential amino acids needed in the diet; human beings cannot synthesize it from simpler metabolites. Young adults need about 31 mg of this amino acid per day per kg (14 mg per lb) of body weight. Phenylalanine can be degraded into simpler compounds by the enzymes of the body and is readily converted to the amino acid tyrosine. Phenylketonuria (PKU), an inherited disease that, if left untreated, results in retarded mental development in children, has been shown to be associated with the lack of activity of the enzyme that converts phenylalanine to tyrosine. This results in the buildup of phenylalanine in the blood, an event leading to several pathological consequences. The incidence of this disease, about one in every 10,000 births, is high enough to have prompted several states to institute regular screening procedures for the detection of the disease in newborns. If diagnosed early the disease can be controlled to a great extent by administering a diet very low in phenylalanine. Phenylalanine contributes to the structure of proteins into which it has been incorporated by the tendency of its side chain to participate in hydrophobic interactions (see isoleucine). This amino acid was first isolated from a natural source (lupine sprouts) in 1879; it was first chemically synthesized in 1882.

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"phenylalanine." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

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"phenylalanine." The Columbia Encyclopedia, 6th ed.. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/phenylalanine

phenylalanine

phen·yl·al·a·nine / ˌfenəlˈaləˌnēn; ˌfēnəl-/ • n. Biochem. an amino acid, C6H5CH2CH(NH2)COOH, widely distributed in plant proteins. It is an essential nutrient in the diet of vertebrates.

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"phenylalanine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

"phenylalanine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (August 21, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/phenylalanine

"phenylalanine." The Oxford Pocket Dictionary of Current English. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/phenylalanine

phenylalanine

phenylalanine An essential amino acid; in addition to its role in protein synthesis, it is the metabolic precursor of tyrosine (and hence noradrenaline, adrenaline, and the thyroid hormones). Dietary tyrosine spares phenylalanine, so reducing the requirement.

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"phenylalanine." A Dictionary of Food and Nutrition. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

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"phenylalanine." A Dictionary of Food and Nutrition. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/phenylalanine

phenylalanine

phenylalanine (fee-nyl-al-ă-neen) n. an essential amino acid that is readily converted to tyrosine. Blockade of this metabolic pathway gives rise to phenylketonuria.

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"phenylalanine." A Dictionary of Nursing. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

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phenylalanine

phenylalanine An aromatic, nonpolar amino acid; it occurs in proteins and is essential for humans.

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"phenylalanine." A Dictionary of Zoology. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

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phenylalanine

phenylalanine An aromatic, non-polar amino acid.

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"phenylalanine." A Dictionary of Plant Sciences. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

"phenylalanine." A Dictionary of Plant Sciences. . Encyclopedia.com. (August 21, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/phenylalanine

"phenylalanine." A Dictionary of Plant Sciences. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/phenylalanine

phenylalanine

phenylalanine See amino acid.

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"phenylalanine." A Dictionary of Biology. . Encyclopedia.com. 21 Aug. 2017 <http://www.encyclopedia.com>.

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"phenylalanine." A Dictionary of Biology. . Retrieved August 21, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/phenylalanine-1