Tyrosine (from the Greek tyros, for "cheese", where it was first discovered) is one of the 20 amino acids that are used by cells to synthesize proteins. 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. Other important biological functions of tyrosine are as a precursor of the thyroid hormone, thyroxine and of the biologically active catecholamines, dopamine, noradrenaline and adrenaline.
Chemical properties: