Tyrosine
Tyrosine comes from the Greek 'tyros', which means 'cheese'. German chemist Justus von Liebig discovered this amino acid in 1846. Two years later, Warren de la Rue obtained Tyrosine during an investigation on the composition of the cochineal insect. Finally, Emil Erlenmeyer and Lipp first accomplished the synthesis of this amino acid by treating p-aminophenylalanine with nitrous acid. The optical isomers of synthetic Tyrosine were later separated by Emil Fischer by crystallization of the brucine or cinchonine salts of benzoyltyrosine.
Chemical Structure of L-Tyrosine
Identifiers and properties of Tyrosine
IUPAC Name: (2S)-2-Amino-3-(4-hydroxyphenyl)propanoic acid
Symbol: Three-letter code - Tyr. One-letter code - Y
Molecular Weight (Molar Mass): 181.18854 g/mol
Molecular Formula (Structural Formula): C9H11NO3
Canonical SMILES: C1=CC(=CC=C1CC(C(=O)O)N)O
Isomeric SMILES: C1=CC(=CC=C1C[C@@H](C(=O)O)N)O
InChIKey Identifier: OUYCCCASQSFEME-QAXLLPJCDY
CAS Number: 60-18-4
MDL Number: MFCD00002606
Melting point: 290 °C
RNA codons: TAC, TAT
Solubility in water: 0.45 g/L (25 °C); pKa - 2,20; pKb - 9,11
Rf value in n-butanol/acetic acid/water = 12:3:5 - 0.45
2D Molfile: Get the molfile
3D PDB file: Get the PDB file
Other names: 3-(4-Hydroxyphenyl)-L-alanine; (S)-alpha-Amino-4-hydroxybenzenepropanoic acid; (-)-alpha-Amino-p-hydroxyhydrocinnamic acid; L-p-Tyrosine; p-Tyrosine; (S)-Tyrosine; L-Beta-(p-Hydroxyphenyl)alanine; (S)-alpha-Amino-4-hydroxybenzenepropanoic acid
What is the role of Tyrosine?
Generally speaking, Tyrosine represents a starting material for neurotransmitters. This amino acid also increases plasma neurotransmitter levels, especially dopamine and noradrenalin, as well as participates in the synthesis of enkephalins providing pain-relieving effects in the body. The aforementioned compounds are very important in terms of brain health, since they are responsible for transmitting nerve impulses and preventing conditions like depression. Besides, dopamine is also essential for the mental functioning and mood, and therefore is widely used to treat mild depression and even stimulate sex drive. According to the numerous studies that were carried out throughout the world, this amino acid proved to be efficient in alleviating stress, anxiety and kept the patients generally more alert.
Tyrosine is known worldwide for supporting and assisting neurotransmitters in the brain. It is particularly important for people experiencing stress, aged, or tired, because in these people, the availability of Tyrosine is depleted. This amino acid, if obtained in full, helps reduce stress, improves mental alertness and mood, and even acts as an appetite suppressant.
Tyrosine is admitted to be essential for the production of a number of important hormones like thyroxin, which plays a key role in regulating metabolism, mental health, skin health, and the human growth rate. Besides, it is known for reducing body fat content, for helping to produce skin and hair pigment and for positively influencing thyroid, pituitary and adrenal gland.
Tyrosine is a precursor to thyroid, adrenocortical hormones and to dopamine. Some of the symptoms of its deficiency include low body temperature, low blood-pressure and restless legs'. Tyrosine derives from phenylalanine. Tyrosine is capable of producing toxic reactions, in excessive dosages of itself, or of phenylalanine, as has been demonstrated when rats fed a low protein diet, which contained more than 3% phenylalanine, developed lesions on paws and eyes, and had growth and food intakes depressed, all of which is identical with tyrosine toxicity. The pigment of skin and hair, melanin, is derived from tyrosine.
Therapeutically tyrosine has been employed to enhance its derivatives (dopa, dopamine, norepinephrine, epinephrine) as well as its ability to alter brain function. Brain tyrosine levels are most conveniently raised by ingestion of pure tyrosine, with a high carbohydrate meal to lower levels of competing amino acids. A high protein meal will increase blood and brain tyrosine to a degree but not enough to effect neurotransmitter synthesis greatly. Physiologically active neurons are highly responsive to neurotransmitters such as tyrosine (and choline) and will actively synthesize neurotransmitters from these substances. There are very few side effects resulting from even fairly large doses of tyrosine. Wurtman who has done much research into this area of biochemistry suggests that if neurons (nerve cells) are not active the precursor is not used. If the neurons are active however, a particular dose of tyrosine can either reduce blood pressure in hypertension, or increase it in haemmorrhagic shock, by virtue of the provision of the tyrosine for neurotransmitter synthesis, these active neurons, will then produce the particular physiologically desirable effect.
Tyrosine is reported to help some Parkinson patients, and to aid in relieving some depression cases. The use in depression of such drugs as monoamine oxidase inhibitors and tricyclic antidepressants involves an increase in the brain's levels of substances such as serotonin and norepinephrine, either by slowing down their degradation, or by prolonging their action. The use of neurotransmitter precursors, which can increase the levels of serotonin and norepinephrines is another way of achieving a similar end. The use of their precursors tryptophan and tyrosine can therefore be seen to be a logical step in this direction. Tyrosine has been found to be most effective when there exists a deficiency state. Patients who have previously responded to amphetamines may respond well to tyrosine therapy.
There is evidence that small doses of tyrosine are more effective in increasing brain levels of neurotransmitters, than large doses. Although blood and brain levels of tyrosine will increase with large doses, there appears to be an inhibition of the enzyme tyrosine hydroxylase which converts tyrosine to neurotransmitters, when large amounts of tyrosine are present.
Tyrosinemia
Tyrosinemia is a rare genetic disorder characterized by elevated levels of the amino acid tyrosine in the blood. This condition is caused by a deficiency in one of the enzymes responsible for breaking down tyrosine, leading to its accumulation. There are three main types of tyrosinemia, each resulting from a deficiency in a different enzyme:
Tyrosinemia Type 1 (I) - hepatorenal tyrosinemia: This is the most severe form, caused by a deficiency in the enzyme fumarylacetoacetate hydrolase (FAH). It primarily affects the liver and kidneys, leading to liver failure, kidney dysfunction, and neurological problems. Symptoms typically appear in infancy.
Tyrosinemia Type 2 (II) - oculocutaneous tyrosinemia: This form is due to a deficiency in tyrosine aminotransferase (TAT). It primarily affects the eyes, skin, and mental development. Symptoms include painful eye lesions, skin abnormalities, and intellectual disabilities.
Tyrosinemia Type 3 (III): This rare form is caused by a deficiency in the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPD). It is less severe than Type I and II and primarily affects the nervous system, potentially leading to intellectual disabilities and seizures.
Diagnosis of tyrosinemia is typically made through blood and urine tests that reveal elevated levels of tyrosine and its byproducts. Genetic testing can confirm the specific enzyme deficiency.
Treatment varies depending on the type but generally includes a low-tyrosine diet to limit the intake of this amino acid and medications such as nitisinone, which can inhibit the production of toxic byproducts. Early diagnosis and management are crucial to prevent serious health complications and improve the quality of life for affected individuals.
Dietary Sources
Tyrosine is a non-essential amino acid, meaning that the human body can synthesize it from another amino acid called phenylalanine. However, certain dietary sources can provide tyrosine directly, contributing to the overall availability of this amino acid in the body. Here are some common sources of tyrosine.
1. Protein-Rich Foods
• Meat: Tyrosine is abundant in various types of meat, such as beef, pork, lamb, and poultry.
• Fish: Fish, especially high-protein varieties like salmon, tuna, and trout, are good sources of tyrosine.
• Eggs: Both egg whites and yolks contain tyrosine, with slightly higher concentrations found in the egg whites.
2. Dairy Products
• Cheese: Certain types of cheese, including Swiss, cheddar, and mozzarella, contain notable amounts of tyrosine.
• Yogurt: Yogurt is another dairy product that contributes to dietary tyrosine intake.
3. Plant-Based Sources
• Soy Products: Foods like tofu and tempeh made from soybeans are good sources of tyrosine for individuals following a vegetarian or vegan diet.
• Nuts and Seeds: Almonds, peanuts, pumpkin seeds, and sesame seeds contain tyrosine.
• Legumes: Beans, lentils, and peas also provide some amount of tyrosine.
4. Whole Grains
• Quinoa: This whole grain is not only a good source of protein but also contains tyrosine.
• Oats: Oats and oatmeal can contribute to tyrosine intake.
5. Darker Colored Fruits
• Bananas: While not exceptionally high in tyrosine, bananas contain some of this amino acid.
• Avocado: Avocados are rich in various nutrients, including tyrosine.
6. Dietary Supplements
• In some cases, individuals may choose to take tyrosine supplements to meet their nutritional needs, particularly if they have specific dietary restrictions or conditions affecting tyrosine synthesis.
It's important to note that a balanced and varied diet usually provides the necessary amino acids, including tyrosine. However, individuals with certain medical conditions, such as phenylketonuria (PKU), need to be cautious about their phenylalanine intake, as excessive levels can lead to the accumulation of harmful byproducts. Always consult with a healthcare professional or a registered dietitian before making significant changes to your diet or taking supplements.