Tyrosine

3D model of tyrosine

Chemical structure of L-Tyrosine

Tyrosine is an amino acid that is used in the biosynthesis of proteins. It is a non-essential amino acid with the chemical formula C_H__NO_. Tyrosine is encoded by the genetic code as the codons UAC and UAU.

Structure and Properties

Tyrosine is classified as a polar amino acid due to the presence of a hydroxyl group in its side chain. This hydroxyl group makes tyrosine more hydrophilic than other amino acids such as phenylalanine. The presence of the aromatic ring in its structure also allows tyrosine to participate in pi stacking interactions.

Biosynthesis

Biosynthesis of tyrosine

In plants and microorganisms, tyrosine is synthesized from prephenate, a product of the shikimate pathway. In animals, tyrosine is derived from phenylalanine through the action of the enzyme phenylalanine hydroxylase. This conversion is crucial for the metabolism of phenylalanine and the production of tyrosine.

Biological Role

Tyrosine is a precursor to several important neurotransmitters and hormones, including dopamine, norepinephrine, and epinephrine. It is also involved in the synthesis of melanin, the pigment responsible for the color of skin and hair.

Metabolism

Conversion of phenylalanine and tyrosine to its biologically important derivatives

Tyrosine is metabolized in the liver by the enzyme tyrosine aminotransferase, which converts it into p-hydroxyphenylpyruvate. This compound is further metabolized into homogentisate, which is eventually broken down into fumarate and acetoacetate, intermediates in the citric acid cycle.

Degradation

Pathway of tyrosine degradation

The degradation of tyrosine involves several steps, ultimately leading to the production of energy and the generation of metabolic intermediates. Disorders in tyrosine metabolism can lead to conditions such as tyrosinemia and alcaptonuria.

Related Pages

• Phenylalanine
• Amino acid
• Protein biosynthesis
• Neurotransmitter

References

• Phenylalanine and Tyrosine
  Phenylalanine and Tyrosine