Phenylalanine is an essential α-amino acid with the formula C9H11NO2. It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine; this essential amino acid is classified as neutral, nonpolar because of the inert and hydrophobic nature of the benzyl side chain. The L-isomer is used to biochemically form proteins, coded for by DNA. Phenylalanine is a precursor for tyrosine, the monoamine neurotransmitters dopamine and epinephrine, the skin pigment melanin, it is encoded by the codons UUU and UUC. Phenylalanine is found in the breast milk of mammals, it is used in the manufacture of food and drink products and sold as a nutritional supplement for its reputed analgesic and antidepressant effects. It is a direct precursor to the neuromodulator phenethylamine, a used dietary supplement; as an essential amino acid, phenylalanine is not synthesized de novo in humans and other animals, who must ingest phenylalanine or phenylalanine-containing proteins.
The first description of phenylalanine was made in 1879, when Schulze and Barbieri identified a compound with the empirical formula, C9H11NO2, in yellow lupine seedlings. In 1882, Erlenmeyer and Lipp first synthesized phenylalanine from phenylacetaldehyde, hydrogen cyanide, ammonia; the genetic codon for phenylalanine was first discovered by J. Heinrich Matthaei and Marshall W. Nirenberg in 1961, they showed that by using mRNA to insert multiple uracil repeats into the genome of the bacterium E. coli, they could cause the bacterium to produce a polypeptide consisting of repeated phenylalanine amino acids. This discovery helped to establish the nature of the coding relationship that links information stored in genomic nucleic acid with protein expression in the living cell. Good sources of phenylalanine are eggs, liver, beef and soybeans. Another common source of phenylalanine is anything sweetened with the artificial sweetener aspartame, such as diet drinks, diet foods and medication; the Food and Nutrition Board of the U.
S. Institute of Medicine set Recommended Dietary Allowances for essential amino acids in 2002. For phenylalanine plus tyrosine, for adults 19 years and older, 33 mg/kg body weight/day. L-Phenylalanine is biologically converted into L-tyrosine, another one of the DNA-encoded amino acids. L-tyrosine in turn is converted into L-DOPA, further converted into dopamine and epinephrine; the latter three are known as the catecholamines. Phenylalanine uses the same active transport channel as tryptophan to cross the blood–brain barrier. In excessive quantities, supplementation can interfere with the production of serotonin and other aromatic amino acids as well as nitric oxide due to the overuse of the associated cofactors, iron or tetrahydrobiopterin; the corresponding enzymes in for those compounds are the aromatic amino acid hydroxylase family and nitric oxide synthase. Phenylalanine is the starting compound used in the synthesis of flavonoids. Lignan is derived from tyrosine. Phenylalanine is converted to cinnamic acid by the enzyme phenylalanine ammonia-lyase.
The genetic disorder phenylketonuria is the inability to metabolize phenylalanine because of a lack of the enzyme phenylalanine hydroxylase. Individuals with this disorder are known as "phenylketonurics" and must regulate their intake of phenylalanine. Phenylketonurics use blood tests to monitor the amount of phenylalanine in their blood. Lab results may report phenylalanine levels using either mg/dL and μmol/L. One mg/dL of phenylalanine is equivalent to 60 μmol/L. A "variant form" of phenylketonuria called hyperphenylalaninemia is caused by the inability to synthesize a cofactor called tetrahydrobiopterin, which can be supplemented. Pregnant women with hyperphenylalaninemia may show similar symptoms of the disorder, but these indicators will disappear at the end of gestation. Pregnant women with PKU must control their blood phenylalanine levels if the fetus is heterozygous for the defective gene because the fetus could be adversely affected due to hepatic immaturity. A non-food source of phenylalanine is the artificial sweetener aspartame.
This compound is metabolized by the body into several chemical byproducts including phenylalanine. The breakdown problems phenylketonurics have with the buildup of phenylalanine in the body occurs with the ingestion of aspartame, although to a lesser degree. Accordingly, all products in Australia, the U. S. and Canada that contain aspartame must be labeled: "Phenylketonurics: Contains phenylalanine." In the UK, foods containing aspartame must carry ingredient panels that refer to the presence of "aspartame or E951" and they must be labeled with a warning "Contains a source of phenylalanine." In Brazil, the label "Contém Fenilalanina" is mandatory in products which contain it. These warnings are placed to help individuals avoid such foods. Geneticists sequenced the genome of macaques in 2007, their investigations found "some instances where the normal form of the macaque protein looked like the diseased human protein" including markers for PKU. The stereoisomer D-phenylalanine can be produced by conventional organic synthesis, either as a single enantiomer or as a component of the racemic mixture.
It does not participate in protein biosynthesis although it is found in proteins in small amounts - aged proteins and food proteins that have been processed. The biolog
A double referendum was held in Egypt on 23 June 1956. The two issues were the candidacy of Gamal Abdel Nasser for the post of president, a new constitution. Both were approved, with the official figures showing 99.9% in favour of Nasser's candidacy and 99.8% in favour of the constitution. Prior to the vote, Nasser had been consolidating power after ousting Muhammad Naguib and launching a massive crackdown against the Muslim Brotherhood in 1954. Other opposition forces had been outflanked by the Liberation Rally, the official political movement of the state set up by the Revolutionary Command Council following the abolition of political parties in 1953; the Liberation Rally's purpose was to acquire mass support for the RCC across the country and was reorganized into the National Union in 1956. The press endorsed and urged support for the referendums. Another chief contributor to Nasser's growing legitimacy was his personal charisma; the NU chose a constitutional committee to pen the new constitution, although its members were picked by Nasser himself.
The referendums were overwhelmingly supported by the electorate. According to government tallies, Nasser's bid for the presidency and the proposed constitution received unanimous approval by voters. Nasser ran uncontested, nominated by the National Union. Historian Kirk J. Beatie wrote the government figures were fictitious, but it is "impossible to know how accurate they were." Nasser used the vote to promote himself as the protector of democracy, but according to author May Kassem, the vote "was utilized in an authoritarian manner" that only served to consecrate Nasser's rule
Kobuleti Managed Reserve is a protected area in Kobuleti Municipality, Adjara region of Georgia along the Black Sea coast in the northern part of the resort town Kobuleti. Kobuleti Protected Areas were established in 1998 to preserve unique wetland ecosystems recognized by the Ramsar Convention. Kobuleti Protected Areas include Kobuleti Managed Reserve and Kobuleti Strict Nature Reserve located on left and right banks of Shavi Ghele river respectively. Reserve has flat surface with minor erosion by the rivers of Shavi Ghele and Togoni and by a few water drains, it is peat bog which consists of peat moss with hardly noticeable surface elevations which are called locally peat domes. These minor elevations rise 1–3 m above it surroundings. Bog in this area is composed of a single peat layer with thickness from 5 m up to 9 m. Kabuleti is an ancient cultural and trading center with many tourist attractions. In late antiquity major trading routes. Christianity was introduced here by St. Andrew the Apostle in the 1st century.
Since the 1950s local population started building sophisticated houses with huge stairs and balconies. The size of the house represented major investment. Villages around Kobuleti till present day has examples of traditional Lazeti dwellings. In vicinity of Kobuleti there are ruins of bridges from early middle ages. Kobuleti Managed Reserve arranged trails, it is possible to walk along sphagnum bog. Kobuleti Strict Nature Reserve