Tuesday, August 28, 2007

Cytosine

Cytosine

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Cytosine
IUPAC name 4-amino-3H-pyrimidin-2-one
Identifiers
CAS number 71-30-7
PubChem 597
MeSH Cytosine
SMILES C1=C(NC(=O)N=C1)N
Properties
Molecular formula C4H5N3O
Molar mass 111.102
Melting point

320 - 325°C (decomp)
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references
Not to be confused with cysteine .

Cytosine is one of the 5 main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and 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 hydrogen bonds with guanine.

[edit] History

Cytosine was first discovered in 1894 when it was isolated from calf thymus tissues. A structure was proposed in 1903, and was synthesized (and thus confirmed) in the laboratory in the same year.

Cytosine recently found use in quantum computation. The first time any quantum mechanical properties were harnessed to process information took place on August 1st in 1998 when researchers at Oxford implemented David Deutsch's algorithm on a two qubit NMRQC (Nuclear Magnetic Resonance Quantum Computer) based on the cytosine molecule.

[edit] Chemical reactions

Cytosine can be found as part of DNA, 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).

In 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 the DNA repair enzymes such as uracil glycosylase, which cleaves a uracil in DNA.

Cytosine can also be methylated into 5-methylcytosine by an enzyme called DNA methyltransferase.

[edit] External links



v • d • e
Major families of biochemicals
Peptides | Amino acids | Nucleic acids | Carbohydrates | Lipids | Terpenes | Carotenoids | Tetrapyrroles | Enzyme cofactors | Steroids | Flavonoids | Alkaloids | Polyketides | Glycosides
Analogues of nucleic acids: Types of Nucleic Acids Analogues of nucleic acids:
Nucleobases: Purine (Adenine, Guanine) | Pyrimidine (Uracil, Thymine, Cytosine)
Nucleosides: Adenosine/Deoxyadenosine | Guanosine/Deoxyguanosine | Uridine | Thymidine | Cytidine/Deoxycytidine
Nucleotides: monophosphates (AMP, UMP, GMP, CMP) | diphosphates (ADP, UDP, GDP, CDP) | triphosphates (ATP, UTP, GTP, CTP) | cyclic (cAMP, cGMP, cADPR)
Deoxynucleotides: monophosphates (dAMP, TMP, dGMP, dCMP) | diphosphates (dADP, TDP, dGDP, dCDP) | triphosphates (dATP, TTP, dGTP, dCTP)
Ribonucleic acids: RNA | mRNA | piRNA | tRNA | rRNA | ncRNA | gRNA | shRNA | siRNA | snRNA | miRNA | snoRNA
Deoxyribonucleic acids: DNA | mtDNA | cDNA | plasmid | Cosmid | BAC | YAC | HAC
Analogues of nucleic acids: GNA | PNA | TNA | Morpholino | LNA


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