Adenine[a] (symbolA,[2] orAde) is apurinenucleotide base that is found inDNA,RNA, andATP.[3] Usually a white crystalline subtance.[3] The shape of adenine is complementary and pairs to eitherthymine in DNA oruracil in RNA.[3] In cells adenine, as an independent molecule, is rare. It is almost alwayscovalently bound to become a part of a larger biomolecule.
Adenine forms severaltautomers, 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.[5][6]
Adenine on Crick and Watson's DNA molecular model, 1953. The picture is shown upside down compared to most modern drawings of adenine, such as those used in this article.
In older literature, adenine was sometimes calledVitamin B4, but is no longer considered a vitamin.[8][3] Due to it being synthesized by the body and not essential to be obtained by diet, it does not meet the definition ofvitamin and is no longer part of theVitamin B complex. However, two B vitamins,niacin andriboflavin, bind with adenine to form the essential cofactorsnicotinamide adenine dinucleotide (NAD) andflavin adenine dinucleotide (FAD), respectively.Hermann Emil Fischer was one of the early scientists to study adenine.
It was named in 1885 byAlbrecht Kossel afterGreekἀδήν aden "gland", in reference to the pancreas, from which Kossel's sample had been extracted.[9][10]
On August 8, 2011, a report, based onNASA studies withmeteorites found onEarth, was published suggesting building blocks ofDNA andRNA (adenine,guanine and relatedorganic molecules) may have been formed extraterrestrially inouter space.[13][14][15] In 2011, physicists reported that adenine has an "unexpectedly variable range of ionization energies along its reaction pathways" which suggested that "understanding experimental data on how adenine survives exposure toUV light is much more complicated than previously thought"; these findings have implications forspectroscopic measurements ofheterocyclic compounds, according to one report.[16]
^Plützer, Chr.; Kleinermanns, K. (2002). "Tautomers and electronic states of jet-cooled adenine investigated by double resonance spectroscopy".Phys. Chem. Chem. Phys.4 (20):4877–4882.Bibcode:2002PCCP....4.4877P.doi:10.1039/b204595h.
^M. J. Nowak; H. Rostkowska; L. Lapinski; J. S. Kwiatkowski; J. Leszczynski (1994). "Experimental matrix isolation and theoretical ab initio HF/6-31G(d, p) studies of infrared spectra of purine, adenine and 2-chloroadenine".Spectrochimica Acta Part A: Molecular Spectroscopy.50 (6):1081–1094.Bibcode:1994AcSpA..50.1081N.doi:10.1016/0584-8539(94)80030-8.ISSN0584-8539.
^[1], "Process for preparing adenine", issued 1966-11-10
^Oro J, Kimball AP (August 1961). "Synthesis of purines under possible primitive earth conditions. I. Adenine from hydrogen cyanide".Archives of Biochemistry and Biophysics.94 (2):217–27.doi:10.1016/0003-9861(61)90033-9.PMID13731263.
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