What Is L-Tyrosine?
L-tyrosine is an aromatic amino acid found mainly in dairy products and legumes.
L-tyrosine is a non-essential amino acid and is synthesized in the body from the essential amino acid phenylalanine by the action of enzymes in liver cells. It is a raw material for neurotransmitters (dopamine, adrenaline, noradrenaline, etc.) and melanin. In the thyroid gland, thyroxine, one of the thyroid hormones, is synthesized from L-tyrosine and iodine.
Uses of L-Tyrosine
1. Food and Medical Applications
L-tyrosine is used in food applications (food additives, supplements, etc.) and medical applications.
L-tyrosine is seldom deficient in the body since it is synthesized by the body and is available through food sources. Under these circumstances, the neurotransmitter made from L-tyrosine is deficient, necessitating the need to supplement L-tyrosine externally.
By actively taking L-tyrosine supplements or consuming L-tyrosine-rich foods, the neurotransmitter can be replenished, maintaining normal brain function. In medical use, this amino acid is used as a component of infusions administered to patients undergoing surgery.
Properties of L-Tyrosine
L-tyrosine’s molecular formula is C9H11NO3 and its molecular weight is 181.19. It is a shiny needle-like crystal that is insoluble in water. It also contains a benzene ring, which can be detected by the “xanthoprotein reaction,” a protein coloration reaction. L-tyrosine has optical isomers (L-L-tyrosine and D-L-tyrosine) with CAS numbers 60-18-4 (L-L-tyrosine) and 556-02-5 (D-L-tyrosine).
Types of L-Tyrosine
Of the optical isomers of L-tyrosine, the L-L-tyrosine is found in most living organisms. L-L-tyrosine is also used in food additives and pharmaceuticals.
L-L-tyrosine is produced by various manufacturers and sold in milligram to kilogram volumes. The D-body of the amino acid is distributed in very few organisms, and D-L-tyrosine is an amino acid produced by the bacterium Bacillus subtilis.
Other Information on L-Tyrosine
1. Xanthoprotein Reaction
This reaction detects amino acids containing benzene rings (L-tyrosine, phenylalanine, tryptophan, etc.). Concentrated nitric acid is added to an aqueous solution of amino acids containing benzene rings, and the solution turns yellow when boiled. The solution is then cooled, and when ammonia water is added, the color of the solution changes to orange-yellow.
2. Relationship to Disease
Phenylketonuria
L-tyrosine is a substance produced by the hydroxylation of phenylalanine by the enzyme phenylalanine hydroxylase. A congenital abnormality in phenylalanine hydroxylase results in a disease called phenylketonuria. In phenylketonuria, phenylalanine is not easily metabolized, resulting in L-tyrosine deficiency.
Leukoderma
L-tyrosine is the raw material for melanin. When melanin is produced, the benzene ring of L-tyrosine is hydroxylated by the enzyme tyrosinase to produce a substance called L-dopa. Mutations in the tyrosinase gene result in leukoderma. Leukoderma causes the skin and hair to become whitish because melanin is not produced as easily.
Cancer
L-tyrosine in proteins is phosphorylated by the enzyme L-tyrosine kinase, which converts the hydroxy group to a phosphate ester. L-tyrosine kinase is a substance that stimulates cell growth. If L-tyrosine kinase is constantly activated for some reason, cells increase abnormally and cancer develops.
3. Effect on Prevention of Gray Hair
L-tyrosine is believed to be effective in preventing gray hair because it is involved in the production of melanin. However, excessive intake may increase skin blemishes due to melanin production.