tyrosin

 A white crystalline nitrogenous substance<--amino acid--> present in small amount in the pancreas and spleen, and formed in large quantity from the decomposition of proteid matter by various means, -- as by pancreatic digestion, by putrefaction as of cheese, by the action of boiling acids, etc. Chemically, it consists of oxyphenol and amidopropionic acid, and by decomposition yields oxybenzoic acid, or some other benzol derivative.  [1913 Webster]