ADENINE occurs in the pancreas and widely elsewhere in the animal kingdom, as well as in beer yeast and tea leaves. It has been prepared synthetically and also by decomposition of nucleic acids and other complex animal substances. It is a colour less solid, crystallizing with three molecules of water, and melting, with decomposition, at 360-365° C. It is a purine base, 6-amino purine (See PURINES. )