Amino Acid Phenylalanine Applications

Amino Acid Phenylalanine Applications Phenylalanine is an electrically neutral amino acid with the chemical formula C9H11NO2. This essential amino acid is one of 20 building blocks of proteins in humans. Due to its benzyl group, phenylalanine is hydrophobic. Since its discovery in 1879, phenylalanine has been studied for its antidepressant and analgesic effects. The synthesis of phenylalanine is complex and does not occur in mammals. The metabolism of phenylalanine produces various hormones and neurotransmitters. Genetic mutations can result in several disorders relating to the metabolism of phenylalanine. This report will identify the biological importance of the amino acid phenylalanine by examining its history, uses, metabolic pathways and disorders, and biological synthesis. Discovery and History Schulze and Barbieri discovered phenylalanine in plant sprouts in 1879. The researchers extracted phenylalanine copper salts from Lupinus Zuteus seedlings, which were refined to isolate phenylalanine (â€Å"L-Phenylalanine ,† n.d.). Before 1940, research on phenylalanine did not describe its biological metabolism during the formation of tyrosine. Womack and Rose showed the essentiality and dependence on phenylalanine in the diet of rats. Dietary intake of tyrosine in the rats was deemed nonessential. Evidence from the trials proved that phenylalanine is the precursor of tyrosine, but phenylalanine cannot be synthesized from tyrosine (Matthews, 2007). The discovery of the codon of phenylalanine was a significant breakthrough in determining the relationship between messenger ribonucleic acid and protein production. In 1961, Matthaei and Nirenberg repeatedly inserted uracil nucleotides into E. coli bacteria, producing long phenylalanine peptide chains. The researchers deduced that the codons for phenylalanine include UUU and UUC (â€Å"Phenylalanine,† 2009). In the 1960s, a more efficient method of phenylalanine production resulted in the large-scale fermentation of phenylalanine. This metho d was incorporated into the nutritional supplement and drug industries (â€Å"L-Phenylalanine,† n.d.). Phenylalanine supplements are currently used to treat depression, chronic pain, Parkinson’s disease, and vitiligo (â€Å"Supplements with Similar,† n.d.). Since 1981, aspartame has been used as a food additive in Canada. Aspartame degrades through metabolism and digestion to form phenylalanine. Phenylalanine has recently been under intense scrutiny due to its elevated levels in aspartame, and the occurrence of phenylketonuria (â€Å"Aspartame,† 2005). Importance and Uses Phenylalanine is an essential amino acid in the diet of humans. Mammals cannot form benzene rings, therefore limiting the biosynthesis of phenylalanine in humans (Kretchmer & Etzwiler, 1958). Phenylalanine is important in amino acid metabolism and the synthesis of structural proteins in tissue. The concentrations of phenylalanine control the amounts of other electrically neutral amino ac ids in the brain (Humphries, Pretorius, & Naude, 2007). Phenylalanine is an essential building block for many hormones and neurotransmitters. Phenylalanine is converted into DOPA, dopamine, epinephrine, norepinephrine, phenylethylamine, and phenylacetate (Humphries et al., 2007). Depression can be treated with phenylalanine medication. Treatment of oral and intravenous application of deprenyl plus phenylalanine has significant antidepressant action (Birkmayer, Linauer, Riederer, & Knoll, 1984). While many natural health and nutritional companies claim D-phenylalanine is effective in chronic pain reduction, clinical studies have determined no significant analgesic results (Walsh, Ramamurthy, Schoenfeld, & Hoffman, 1986). L-DOPA, a molecule composed of a phenylalanine base, has been used as a symptom repressor in Parkinson’s disease for over fifty years. In 1967, Cortzias showed in his report on Parkinson’s disease, that L-DOPA has a noteworthy rehabilitative quality in reducing rigidity and akinesia (McDowell & Lee, 1970). The major problem of Parkinson’s disease is lowered levels of dopamine in the brain due to trauma or dysfunction of dopaminergic cells. Administered L-DOPA is able to cross the blood-brain barrier for conversion into dopamine, thus increasing dopamine levels (â€Å"Oxidation of L-dopa,† 2002). Current research suggests that phenylalanine administration along with ultraviolet radiation aids in vitiligo patients. The phenylalanine absorbs the radiation resulting in slight pigmentation changes in the skin (â€Å"Supplements with Similar,† n.d.).