Tyrosine (abbreviated as Tyr or Y) or 4-hydroxyphenylalanine, is one of the 20 amino acids that are used by cells to synthesize proteins. This is a non-essential amino acid and it's found in large quantities in casein. In fact, the word "tyrosine" is from the Greek tyros, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese. Functions Aside from being a proteogenic amino acid, tyrosine has a special role by virtue of the phenol… (More on Tyrosine)