Aromatic amino acid. Structure is the same as phenylalanine, but with a hydroxyl group added to the aromatic ring. This hydroxyl group is a common site of phosphorylation by tyrosine kinases.

Formula: C₉H₁₁NO₃
Molecular Weight: 181.19
Three-letter code: Tyr
One-letter code: Y

A nonessential amino acid which is derived by the body from phenylalanine. Tyrosine is used to make the neurotransmitters dopamine, norepinephrine, and epinephrine by combining with vitamin B6, folic acid, and copper; it is also used to make the skin pigmentation melanin.

A lack of tyrosine can result in depression or Parkinson's disease. People affected by Phenylketonuria cannot metabolize phenylalanine, and therefore tend to lack tyrosine as well.

Dietary supplements can be taken in the form of L-Tyrosine. Dairy products, meat, fish, wheat, oats, and many other foods also contain tyrosine.

structural formula of tyrosine:

     H        H
      \      /
       C == C      H    H      O
      /      \     |    |     //
O -- C        C -- C -- C -- C -- O
|     \\    //     |    |          \
H      C -- C      H    N           H
      /      \         / \
     H        H       H   H

        tyrosine
        C9H11NO3