CYTOSINE (/ˈsaɪtəˌsiːn, -ˌziːn, -ˌsɪn/ ; C) is one of the
four main bases found in
RNA , along with adenine , guanine ,
and thymine (uracil in RNA). It is a pyrimidine derivative, with a
heterocyclic aromatic ring and two substituents attached (an amine
group at position 4 and a keto group at position 2). The nucleoside of
cytosine is cytidine . In Watson-Crick base pairing , it forms
three(3) hydrogen bonds with guanine .
* 1 History
* 2 Chemical reactions
* 3 Theoretical aspects
* 4 References
* 5 External links and citations
Cytosine was discovered and named by
Albrecht Kossel and Albert
Neumann in 1894 when it was hydrolyzed from calf thymus tissues. A
structure was proposed in 1903, and was synthesized (and thus
confirmed) in the laboratory in the same year.
In 1997 cytosine was used in an early demonstration quantum
information processing when Oxford University researchers implemented
Deutsch-Jozsa algorithm on a two qubit nuclear magnetic resonance
quantum computer (NMRQC) .
In March 2015,
NASA scientists reported the formation of cytosine,
along with uracil and thymine, from pyrimidine under the space-like
laboratory conditions, which is of interest because pyrimidine has
been found in meteorites although its origin is unknown.
Cytosine with numbered components.
Methylation occurs on carbon
Cytosine can be found as part of DNA, as part of RNA, or as a part of
a nucleotide . As cytidine triphosphate (CTP), it can act as a
co-factor to enzymes, and can transfer a phosphate to convert
adenosine diphosphate (ADP) to adenosine triphosphate (ATP).
DNA and RNA, cytosine is paired with guanine . However, it is
inherently unstable, and can change into uracil (spontaneous
deamination ). This can lead to a point mutation if not repaired by
DNA repair enzymes such as uracil glycosylase, which cleaves a
uracil in DNA.
When found third in a codon of
RNA , cytosine is synonymous with
uracil , as they are interchangeable as the third base. When found as
the second base in a codon, the third is always interchangeable. For
example, UCU, UCC, UCA and UCG are all serine , regardless of the
Cytosine can also be methylated into 5-methylcytosine by an enzyme
DNA methyltransferase or be methylated and hydroxylated to make
5-hydroxymethylcytosine . Active enzymatic deamination of cytosine or
5-methylcytosine by the
APOBEC family of cytosine deaminases could
have both beneficial and detrimental implications on various cellular
processes as well as on organismal evolution. The implications of
deamination on 5-hydroxymethylcytosine, on the other hand, remains
Cytosine has not been found in meteorites, which suggests the first
DNA had to look elsewhere to obtain this building
Cytosine likely formed within some meteorite parent bodies,
however did not persist within these bodies due to an effective
deamination reaction into uracil .
* ^ Dawson, R.M.C.; et al. (1959). Data for Biochemical Research.
Oxford: Clarendon Press.
* ^ "Cytosine".
Random House .
* ^ "Cytosine".
Merriam-Webster Dictionary .
* ^ A. Kossel and Albert Neumann (1894) "Darstellung und
Spaltungsprodukte der Nucleïnsäure (Adenylsäure)" (Preparation and
cleavage products of nucleic acids (adenic acid)), Berichte der
Deutschen Chemischen Gesellschaft zu Berlin, 27 : 2215-2222. The name
"cytosine" is coined on page 2219: " … ein Produkt von basischen
Eigenschaften, für welches wir den Namen "Cytosin" vorschlagen." (
… a product with basic properties, for which we suggest the name
* ^ Kossel, A.; Steudel, H. Z. (1903). "Weitere Untersuchungen
über das Cytosin". Physiol. Chem. 38: 49. doi
* ^ Jones, J.A.; M. Mosca (1998-08-01). "Implementation of a
quantum algorithm on a nuclear magnetic resonance quantum computer".
J.Chem.Phys. 109 (109): 1648–1653. doi :10.1063/1.476739 . Retrieved
* ^ Marlaire, Ruth (3 March 2015). "
NASA Ames Reproduces the
Building Blocks of Life in Laboratory".
NASA . Retrieved 5 March 2015.
* ^ Chahwan R.; Wontakal S.N.; Roa S. (2010). "Crosstalk between
genetic and epigenetic information through cytosine deamination".
Trends in Genetics. 26 (10): 443–448. PMID 20800313 . doi
* ^ Tasker, Elizabeth. "Did the Seeds of Life Come from Space?".
Scientific American Blog Network. Retrieved 2016-11-24.
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