Definition
Cytosine (C) is one of the four heterocyclic nitrogenous bases found in DNA (A, T, C, and G) and RNA (A, U, C, and G). It is a pyrimidine with two functional group substituents: an amine at the C4 position and a keto group at the C2 position. When cytosine is combined with ribose via a glycosidic linkage between its N1 nitrogen and the C1 position of the sugar, it forms a nucleoside called cytidine; removal of the 2′OH group of this molecule results in the formation of 2′-deoxycytidine also known as deoxycytidine. In Watson-Crick base pairing in nucleic acids, these derivatives form three hydrogen bonds with guanine.
Cytosine and its derivatives hydrolyze fairly rapidly under physiological conditions to give uracil via deamination, with a half-life of approximately 73 years at 37 °C at pH 7. In biological systems, this relatively rapid loss of structural genetic information is corrected by DNA repair enzymes.
Cytosine has been synthesized under simulated prebiotic conditions...
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Cleaves, H.J.(. (2014). Cytosine. In: Amils, R., et al. Encyclopedia of Astrobiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-27833-4_387-4
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DOI: https://doi.org/10.1007/978-3-642-27833-4_387-4
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Publisher Name: Springer, Berlin, Heidelberg
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