It is an amino acid that we find in many proteins, both in animal and vegetable ones, it is the Phenylalanine, a very useful substance for our health if we take it in the correct quantity. I say "take it" because humans are unable to synthesize it from other amino acids, so it is considered an essential amino acid and we must find a way to obtain it from what we eat.
Those who know chemistry will also know that it is an aromatic, neutral and non-polar (therefore hydrophobic) alpha-amino acid, with a chemical formula C9H11NO2.
Phenylalanine in plants
We also find this amino acid in many plants and it is the starting compound used in the synthesis of flavonoids even if the phenylalanine also derive lignans, non-flavonoid polyphenols, as well as tyrosine.
Let's see better what happens. In plants thanks toammoniacal phenylalanine enzyme our amino acid is converted into cinnamic acid, an acid with a very bitter taste and white in color and very fragrant. It is very reminiscent of honey and flowers, which is why we find it very often used in the field of cosmetics. From this acid we can also obtain cinnamate, a compound that we can find in pharmacology where it is used to make anthelmintic drugs, that is, which eliminate some worm infestations.
Schulze and Barbieri they were the first to describe phenylalanine when in 1879 they identified a compound with the empirical formula C9H11NO2 in yellow lupine seeds (botanical name Lupinus luteus). Less than 5 years later and Erlenmeyer and Lipp, in 1882, synthesized phenylalanine from phenylacetaldehyde, hydrogen cyanide and ammonia. Many years pass and then, in 1961, the genetic codon for phenylalanine is discovered.
This step forward is attributed to J. Heinrich Matthaei and Marshall W. Nirenberg who managed to do this by establishing the coding relationship between the information stored in the genomic nucleic acids with the protein expression of the cells.
This amino acid plays a vital role in the synthesis process any type of peptide, not only plastic, but also enzymatic, hormonal, etc., therefore in its L- form it can be considered a sort of “structural brick” of proteins.
Another important role played is that of precursor, and it is so on many occasions, even completely different ones.
It is a precursor for example dopamine, noradrenaline and adrenaline.
Dopamine is a very important neurotransmitter for brain metabolism, it is missing when you get Parkinson's disease and is essential for noradrenaline production. The latter is also an important neurotransmitter of the catecholamine type and belongs to the sympathetic nervous system.
It is one of the "stress hormones" and the well-known adrenaline, the main catecholamine-type neurotransmitter of the sympathetic nervous systemas well as another stress hormone. Phenylalanine is also a precursor of the amino acid tyrosine, thanks to which the biosynthesis of thyroid hormones and levodopa and 2-phenylethylamine, an alkaloid neurotransmitter essential in falling in love, can occur.
When this amino acid accumulates in our body in abnormal quantities, then a genetic pathology called phenylketonuria. Even healthy people with an excess of this substance can experience damage. In much higher than normal quantities, phenylalanine can interfere with the production of serotonin and other aromatic amino acids and also with the production of nitric oxide
To hire Phenylalanine it is necessary to eat foods that contain proteins. We find large quantities of it in meat (for example chicken and beef), in offal (especially liver) but also in fish, eggs, milk and its derivatives. We also find it in legumes, especially in soy, but the first essential source of phenylalanine for humans is breast milk.
Thanks to its function of hormonal precursor - neurotransmitter, phenylalanine is also used in the formulation of analgesic and antidepressant supplements.
We also find it surprisingly in aspartame, a sweetener 200 times more powerful than sugar. If you suffer from phenylketonuria it is best not to use it and avoid all products in which it is contained, including soft drinks.
At the end of the article, let's find out how it is possible to produce the L-phenylalanine. A bacterium from the Escherichia coli group is used which is capable of naturally producing various aromatic amino acids and among these there is phenylalanine, especially in its genetically modified form for industrial use.
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