Organic compound of the purine family, often called a base, consisting of two rings, each containing both nitrogen and carbon atoms, and an amino group.
It occurs free in tea and in combined form in nucleic acid s, ATP , 12 {{/link}}, and several {{link=coenzyme">coenzyme s. In DNA its complementary base is thymine . It or its corresponding nucleoside or nucleotide may be prepared from nucleic acids by selective techniques of hydrolysis .