Adenine is a purine with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate (ATP) and the cofactors nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD), and protein synthesis, as a chemical component of DNA and RNA. the shape of adenine is complementary to either thymine or uracil.
It forms several tautomers
, compounds that can be rapidly interconverted and are often considered equivalent.
The Purine metabolism
involves the formation of Adenine and Guanine
. Both adenine and guanine are derived from the nucleotide inosine monophosphate (IMP), which is synthesised on a pre-existing ribose through a complex pathway using atoms from the amino acids glycine, glutamine, and aspartic acid, as well as formate ions transferred from the coenzyme tetrahydrofolate.
Adenine is one of the two purine nucleobases
(the other being guanine
) used in forming nucleotides
of the nucleic acids
. In DNA, adenine binds to thymine
via two hydrogen bonds
to assist in stabilizing the nucleic acid structures. In RNA, which is used in the cytoplasm
for protein synthesis
, adenine binds to uracil
Adenine forms adenosine, a nucleoside, when attached to ribose, and deoxyadenosine when attached to deoxyribose. It forms adenosine triphosphate (ATP), a nucleotide, when three phosphate groups are added to adenosine. Adenosine triphosphate is used in cellular metabolism as one of the basic methods of transferring chemical energy between chemical reactions.
In older literature, adenine was sometimes called Vitamin B4
. It is no longer considered a true vitamin or part of the Vitamin B
complex. However, two B vitamins, niacin
, bind with adenine to form the essential cofactors nicotinamide adenine dinucleotide
(NAD) and flavin adenine dinucleotide
Some think that, at the origin of life on Earth, the first adenine was formed by the polymerization of five hydrogen cyanide (HCN) molecules. However, this has been criticized by some chemists.