Adenine (A, Ade) is a nucleobase (a purine derivative). Its derivatives have 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). It also has functions in protein synthesis and as a chemical component of DNA and RNA.〔(Definition of Adenine from the Genetics Home Reference ) - National Institutes of Health〕 The shape of adenine is complementary to either thymine in DNA or uracil in RNA.
The image right shows pure adenine, as an independent molecule. When connected into DNA, a covalent bond is formed between deoxyribose sugar and the bottom left nitrogen, so removing the hydrogen. The remaining structure is called an ''adenine residue'', as part of a larger molecule. Adenosine is adenine reacted with ribose as used in RNA and ATP; deoxyadenosine adenine attached to deoxyribose, as is used to form DNA.
Adenine forms several tautomers, compounds that can be rapidly interconverted and are often considered equivalent. However, in isolated conditions, i.e. in an inert gas matrix and in the gas phase, mainly the 9H-adenine tautomer is found.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』