Phenylalanine

Phenylalanine
Systematic name	2-Amino-3-phenyl- propanoic acid
Abbreviations	Phe F
Chemical formula	C₉H₁₁NO₂
Molecular mass	165.19 g mol^-1
Melting point	283 °C
Density	1.29 g cm^-3
Isoelectric point	5.5
pK_a	2.20 9.09
CAS number	63-91-2
SMILES	C1=CC=C(C=C1)CC(C(=O)O)N
Chemical infobox

Phe redirects here. For the BitTorrent feature, see PHE.

Phenylalanine is an essential alpha-amino acid which exists in two forms, a D and an L form, which are enantiomers (mirror-image molecules) of each other. It has a benzyl side chain. Its name comes from its chemical structure's consisting of a phenyl group substituted for one of the hydrogens in the side chain of alanine. Because of its phenyl group, phenylalanine is an aromatic compound. At room temperature, it is a white, powdery solid.
L-Phenylalanine (LPA) is an electrically-neutral amino acid, one of the twenty common amino acids used to biochemically form proteins, coded for by DNA. Its enantiomer, D-phenylalanine (DPA), can be synthesized artificially.

L-phenylalanine is used in living organisms, including the human body, where it is an essential amino acid. L-phenylalanine can also be converted into L-tyrosine, another one of the twenty protein-forming amino acids. L-tyrosine is converted into L-DOPA, which is further converted into dopamine, norepinephrine, and epinephrine (latter three are known as the catecholamines). D-phenylalanine can be converted only into phenylethylamine.

The genetic disorder phenylketonuria (PKU) is an inability to metabolize phenylalanine. Individuals with this disorder are known as "phenylketonurics", and must abstain from consumption of phenylalanine. It is present in many sugarless gums, Monster Munch crisps, and other food products, which are labeled: "Phenylketonurics: Contains phenylalanine." The reason is not that phenylalanine is in the food per se. Aspartame (NutraSweet) is an ester that is hydrolyzed in the body to form phenylalanine, aspartic acid and methanol (wood alcohol), and it is the phenylalanine portion of aspartame which then builds up in the person with PKU. The amounts used in aspartame are an incredibly low risk factor however, as far larger quantities of the amino acid would be obtained through simply consuming any protein at all with phenylalanine content, which would include all complete proteins, as phenylalanine is an essential amino acid.

The synthesized mix DL-Phenylalanine (DLPA), which is a combination of the D- and L- forms (e.g. a racemate: a racemic compound or mixture), is used as a nutritional supplement. Research indicates that DLPA can be an effective part of an overall program to fight chronic pain and depression in some cases, including the mood swings of premenstrual syndrome (PMS). Some sources contend that DLPA can increase energy and mental alertness, as well as heighten the ability to focus in individuals with attention deficit hyperactivity disorder (ADHD).

The genetic codon for phenylalanine was the first to be discovered. Marshall W. Nirenberg discovered that, when he inserted m-RNA made up of multiple uracil repeats into E. coli, the bacterium produced a new protein, made up solely of repeated phenylalanine amino acids.

Phenylalanine uses the same active transport channel as tryptophan to cross the blood-brain barrier, and, in large quantities, interferes with the production of serotonin.

Phenylalanine is contained in most protein rich foods, but especially good sources are dairy products (curd, milk, cottage cheese), avocados, pulses and legumes (particularly lima beans), nuts (peanuts, pistachios, almonds), seeds (piyal seeds), leafy vegetables, whole grains, poultry, fish and other seafoods.

Forms of Phenylalanine
Common name	phenylalanine	D-phenylalanine	L-phenylalanine	DL-phenylalanine
Synonyms	alpha-Amino-beta- phenylpropionic acid	(2R)-2-amino-3- phenylpropanoic acid	(2S)-2-amino-3- phenylpropanoic acid
PubChem
EINECS number
CAS number		673-06-3	63-91-2	150-30-1

Biosynthesis

Phenylalanine cannot be made by animals, which have to obtain it from their diet. It is produced by plants and most microorganisms from prephenate, an intermediate on the shikimate pathway.

Prephenate is decarboxylated with loss of the hydroxyl group to give phenylpyruvate. This is transaminated using glutamate as the nitrogen source to give phenylalanine and α-ketoglutarate.

References

External links

Essential amino acids | Aromatic amino acids

Gourt Home::Gourt :: Phenylalanine

Biosynthesis

References

See also

External links