Tyrosine aminotransferase

Tyrosine_aminotransferase

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  3D structure of Tyrosine aminotransferase

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  Diagram of Tyrosine aminotransferase

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  Final structure of Tyrosine aminotransferase

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  Dimer form of Tyrosine aminotransferase

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  Lysine 280 with PLP in Tyrosine aminotransferase

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  Reaction catalyzed by Tyrosine aminotransferase

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  Tyrosine aminotransferase

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  Active site of Tyrosine aminotransferase

Tyrosine Aminotransferase

Tyrosine aminotransferase (TAT) is an enzyme that plays a crucial role in the metabolism of the amino acid tyrosine. It is a pyridoxal phosphate-dependent enzyme that catalyzes the transamination reaction, converting tyrosine into p-hydroxyphenylpyruvate. This reaction is an important step in the catabolic pathway of tyrosine, ultimately leading to the production of fumarylacetoacetate, which is further broken down into fumarate and acetoacetate.

Function

Tyrosine aminotransferase is primarily found in the liver, where it facilitates the conversion of tyrosine, an aromatic amino acid, into p-hydroxyphenylpyruvate. This reaction involves the transfer of an amino group from tyrosine to an _-keto acid, typically _-ketoglutarate, resulting in the formation of glutamate and p-hydroxyphenylpyruvate. This process is essential for the proper degradation of tyrosine, which is derived from dietary sources or from the hydroxylation of phenylalanine.

Clinical Significance

Deficiency or dysfunction of tyrosine aminotransferase can lead to a metabolic disorder known as tyrosinemia type II, also called Richner-Hanhart syndrome. This condition is characterized by elevated levels of tyrosine in the blood, leading to symptoms such as skin lesions, eye problems, and intellectual disability. The accumulation of tyrosine and its metabolites can cause damage to various tissues, particularly affecting the skin and eyes.

Regulation

The activity of tyrosine aminotransferase is regulated by various factors, including hormonal control and dietary intake. Glucocorticoids and glucagon are known to induce the expression of the TAT gene, increasing the enzyme's activity in response to physiological needs. Conversely, insulin can downregulate its expression. The enzyme's activity is also influenced by the availability of its substrates and cofactors, such as pyridoxal phosphate.

Related Enzymes

Tyrosine aminotransferase is part of a family of aminotransferases, which are enzymes that catalyze the transfer of amino groups between amino acids and _-keto acids. Other related enzymes include alanine aminotransferase and aspartate aminotransferase, which play roles in the metabolism of other amino acids.

Related Pages

• Amino acid metabolism
• Phenylalanine hydroxylase
• Tyrosinemia
• Pyridoxal phosphate