Tyrosine - Definition and Overview

Tyrosine (from the Greek tyros, meaning "cheese", as it was first discovered in cheese), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells to synthesize proteins. It has a phenol side chain.

It plays a key role in signal transduction, since it can be tagged (phosphorylated) with a phosphate group by protein kinases to alter the functionality and activity of certain enzymes. (In its phosphorylated state, it is sometimes referred to as phosphotyrosine.) Other important biological functions of tyrosine are as a precursor of the thyroid hormone, thyroxine and of the biologically active catecholamines (e.g. dopamine, noradrenaline and adrenaline).

Chemical properties:

• Isoelectric point: 5.64
• Mass: 181.19
• Abbreviations: Tyr / Y
• Side chain: hydrophilic
• Chemical formula: C₉O₃H₁₁N (structure)

See also :

• Alkaptonuria
• Tyrosinemia