Tyrosine is an important nutritionally essential amino acid that plays an important role in the metabolism, growth and development of humans and animals, and is widely used in food, feed, medicine and chemical industries. It is often used as a nutritional supplement for patients with phenylketonuria, and as a raw material for the preparation of pharmaceutical and chemical products such as polypeptide hormones, antibiotics, L-dopa, melanin, p-hydroxycinnamic acid, and p-hydroxystyrene. As more high-value-added L-tyrosine derivatives such as danshensu, resveratrol, and hydroxytyrosol are found in organisms, L-tyrosine is increasingly developing in the direction of platform compounds. Tyrosine is one of the 22 kinds of amino acids used by cells to synthesize proteins. It can be used to synthesize proteins in cells. Its codons are UAC and UAU. It is a non-essential amino acid that contains polar side groups and can be synthesized by the human body. The word "tyrosine" comes from the Greek tyros, meaning cheese. It was first discovered in the casein of cheese by the German chemist Justus von Liebig in the early 19th century. When it is used as a functional group or a side group, it is called tyrosyl. Function In addition to being a proteinogenic amino acid, tyrosine has a special role in signal transduction in proteins by means of a phenolic function, which functions as a receptor for phosphate groups transferred by protein kinases (so-called tyrosine kinase receptors). organ, while phosphorylation of hydroxyl groups alters the activity of the target protein. Tyrosine also plays an important role in photosynthesis. In chloroplasts (photosystem II), it is used as an electron donor in the reduction reaction of oxidized chlorophyll, allowing it to deprotonate the phenolic OH-group, and finally in Photosystem II is reduced by four core manganese clusters. Dietary Sources Tyrosine can be synthesized from phenylalanine in the body and can be found in many high-protein foods such as chicken, turkey, fish, milk, yogurt, cheese, cottage cheese, peanuts, almonds, pumpkin seeds, sesame, soybeans, lima beans , found in avocados and bananas.