Adenine

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Adenine is one of the two purine nucleobases used in forming nucleotides of the nucleic acids DNA and RNA. In DNA, adenine (A) binds to thymine (T) via two hydrogen bonds to assist in stabilizing the nucleic acid structures. In RNA, adenine binds to uracil (U).

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Adenine forms adenosine, a nucleoside, when attached to ribose, and deoxyadenosine when attached to deoxyribose, and 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 reactions.

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In older literature, adenine was sometimes called Vitamin B4. However it is no longer considered a true vitamin (see Vitamin B).

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Some think that at the origin of life on Earth, the first adenine was formed by five hydrogen cyanide (HCN) molecules polymerizing.

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Nucleotide: A nucleotide is a monomer or the structural unit of nucleotide chains forming nucleic acids as RNA and DNA. A nucleotide consists of a heterocyclic nucleobase, a pentose sugar (ribose or deoxiribose), and a phosphate or polyphosphate group. Nucleotides also play important roles in cellular energy t...

DNA: :For other uses, see DNA (disambiguation)....

RNA: Ribonucleic acid (RNA) is a nucleic acid consisting of a string of covalently-bound nucleotides. It is biochemically distinguished from DNA by the presence of an additional hydroxyl group, attached to each pentose ring. While RNA usually contains uracil instead of thymine, this is not always true, f...