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Cytosine
Cytosine
(/ˈsaɪtəˌsiːn, -ˌziːn, -ˌsɪn/;[2][3] C) is one of the four main bases found in DNA
DNA
and 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.

Contents

1 History 2 Chemical reactions 3 Theoretical aspects 4 References 5 External links and citations

History[edit] Cytosine
Cytosine
was discovered and named by Albrecht Kossel
Albrecht Kossel
and Albert Neumann in 1894 when it was hydrolyzed from calf thymus tissues.[4][5] 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 the Deutsch-Jozsa algorithm
Deutsch-Jozsa algorithm
on a two qubit nuclear magnetic resonance quantum computer (NMRQC).[6] In March 2015, NASA
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.[7] Chemical reactions[edit]

Cytosine
Cytosine
with numbered components. Methylation
Methylation
occurs on carbon number 5.

Cytosine
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). In DNA
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
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 third base. Cytosine
Cytosine
can also be methylated into 5-methylcytosine by an enzyme called DNA
DNA
methyltransferase or be methylated and hydroxylated to make 5-hydroxymethylcytosine. Active enzymatic deamination of cytosine or 5-methylcytosine by the APOBEC
APOBEC
family of cytosine deaminases could have both beneficial and detrimental implications on various cellular processes as well as on organismal evolution.[8] The implications of deamination on 5-hydroxymethylcytosine, on the other hand, remains less understood. Theoretical aspects[edit] Cytosine
Cytosine
has not been found in meteorites, which suggests the first strands of RNA
RNA
and DNA
DNA
had to look elsewhere to obtain this building block. Cytosine
Cytosine
likely formed within some meteorite parent bodies, however did not persist within these bodies due to an effective deamination reaction into uracil.[9] References[edit]

^ Dawson, R.M.C.; et al. (1959). Data for Biochemical Research. Oxford: Clarendon Press.  ^ "Cytosine". Dictionary.com Unabridged. Random House.  ^ "Cytosine". Merriam-Webster
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 "cytosine".) ^ Kossel, A.; Steudel, H. Z. (1903). "Weitere Untersuchungen über das Cytosin". Physiol. Chem. 38: 49. doi:10.1515/bchm2.1903.38.1-2.49.  ^ 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 2007-10-18.  ^ Marlaire, Ruth (3 March 2015). " NASA
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. doi:10.1016/j.tig.2010.07.005. PMID 20800313.  ^ Tasker, Elizabeth. "Did the Seeds of Life Come from Space?". Scientific American Blog Network. Retrieved 2016-11-24. 

External links and citations[edit]

Wikimedia Commons has media related to Cytosine.

Cytosine
Cytosine
MS Spectrum EINECS number
EINECS number
200-749-5 Shapiro R (1999). "Prebiotic cytosine synthesis: a critical analysis and implications for the origin of life". Proc. Natl. Acad. Sci. U.S.A. 96 (8): 4396–401. doi:10.1073/pnas.96.8.4396. PMC 16343 . PMID 10200273. 

v t e

Nucleic acid
Nucleic acid
constituents

Nucleobase

Purine

Adenine Guanine Hypoxanthine Xanthine Purine
Purine
analogue

Pyrimidine

Uracil Thymine Cytosine Pyrimidine
Pyrimidine
analogue

Unnatural base pair (UBP)

Nucleoside

Ribonucleoside

Adenosine Guanosine 5-Methyluridine Uridine 5-Methylcytidine Cytidine Inosine Xanthosine Wybutosine

Deoxyribonucleoside

Deoxyadenosine Deoxyguanosine Thymidine Deoxyuridine Deoxycytidine Deoxyinosine Deoxyxanthosine

Nucleotide ( Nucleoside
Nucleoside
monophosphate)

Ribonucleotide

AMP GMP m5UMP UMP CMP IMP XMP

Deoxyribonucleotide

dAMP dGMP dTMP dUMP dCMP dIMP dXMP

Cyclic nucleotide

cAMP cGMP c-di-GMP c-di-AMP cADPR

Nucleoside
Nucleoside
diphosphate

ADP GDP m5UDP UDP CDP

dADP dGDP dTDP dUDP dCDP

Nucleoside
Nucleoside
triphosphate

ATP GTP m5UTP UTP CTP ITP XTP

dATP dGTP dTTP dUTP dCTP dITP dXTP

v t e

Purine
Purine
receptor modulators

Receptor (ligands)

P0 (adenine)

Agonists: 8-Aminoadenine Adenine

P1 (adenosine)

Agonists: 2-(1-Hexynyl)-N-methyladenosine 2-Cl-IB-MECA 2'-MeCCPA 4'-O-β-D-Glucosyl-9-O-(6''-deoxysaccharosyl)olivil 5'-N-ethylcarboxamidoadenosine Adenosine ADP AMP Apadenoson ATL-146e ATP BAY 60–6583 Binodenoson Capadenoson CCPA CGS-21680 CP-532,903 Evodenoson GR 79236 LUF-5835 LUF-5845 N6-Cyclopentyladenosine Namodenoson Neladenoson dalanate Piclidenoson Regadenoson SDZ WAG 994 Selodenoson Sonedenoson Tecadenoson UK-432,097

Antagonists: 8-Chlorotheophylline 8-Phenyl-1,3-dipropylxanthine 8-Phenyltheophylline Acefylline Aminophylline ATL-444 Bamifylline Cafedrine Caffeine Caffeine
Caffeine
citrate Cartazolate CGH-2466 CGS-15943 Choline theophyllinate CPX CVT-6883 Dimethazan DMPX DPCPX Dyphylline Enprofylline Etazolate Fenethylline IBMX Isovaleric acid Istradefylline KF-26777 MRE3008F20 MRS-1220 MRS-1334 MRS-1706 MRS-1754 MRS-3777 Paraxanthine Pentoxifylline Preladenant Propentofylline Proxyphylline PSB-10 PSB-11 PSB-36 PSB-603 PSB-788 PSB-1115 Reversine Rolofylline SCH-442,416 SCH-58261 Theacrine Theobromine Theodrenaline Theophylline Tozadenant Tracazolate VUF-5574 ZM-241,385

P2 (nucleotide)

P2X (ATP)

Agonists: 2-Me-SATP α,β-Me-ATP Adenosine ADP AMP Ap4A Ap5A ATP ATPγS BzATP Cibacron blue CTP D-β,γ-Me-ATP GTP HT-AMP Ivermectin L-β,γ-Me-ATP MRS-2219 PAPET-ATP UTP Zinc

Antagonists: 5-BDBD A-317491 A-438079 A-740003 A-804598 A-839977 AF-353 AZ-10606120 AZ-11645373 BBG Calcium Calmidazolium Chelerythrine Copper Emodin
Emodin
(Rheum officinale) Evans Blue GW-791343 HMA Ip5I isoPPADS JNJ-47965567 KN-04 KN-62 Magnesium MRS-2159 NF-023 NF-110 NF-157 NF-279 NF-449 Opiranserin (VVZ-149) Oxidized-ATP Phenol Red Phenolphthalein PPADS PPNDS PSB-12062 Puerarin
Puerarin
(Radix puerariae) Purotoxin 1 RB-2 Ro 0437626 Ro 51 RO-3 Sodium ferulate
Sodium ferulate
(Angelica sinensis, Ligusticum wallichii) Suramin TC-P 262 Tetramethylpyrazine
Tetramethylpyrazine
(ligustrazine) (Ligusticum wallichii) TNP-ATP Zinc

P2Y

Agonists: 2-Me-SADP 2-Me-SATP 2-Thio-UTP 5-Br-UDP 5-OMe-UDP α,β-Me-ATP Adenosine ADP ADPβS Ap3A AR-C 67085MX ATP ATPγS CTP dATP Denufosol Diquafosol IDP ITP INS-365 INS-37217 MRS-2365 MRS-2690 MRS-2693 MRS-2768 MRS-2957 MRS-4062 NF-546 PAPET-ATP PSB-0474 PSB-1114 UDP UDPβS UDP-galactose UDP-glucose UDP-N-acetylglucosamine Up3U UTP UTPγS

Antagonists: 2-Me-SAMP A3P5PS AMPαS Ap4A AR-C 66096 AR-C 67085MX AR-C 69931MX AR-C 118925XX ATP BzATP C1330-7 Cangrelor Clopidogrel Elinogrel Ip5I MRS-2179 MRS-2211 MRS-2279 MRS-2395 MRS-2500 MRS-2578 NF-157 NF-340 PIT PPADS Prasugrel PSB-0739 RB-2 Regrelor Suramin Ticagrelor Ticlopidine UDP

Transporter (blockers)

CNTs

6-Hydroxy-7-methoxyflavone Adenosine dMeThPmR Estradiol KGO-2142 KGO-2173 MeThPmR Phloridzin Progesterone

ENTs

Barbiturates Benzodiazepines Cilostazol Dilazep Dipyridamole Estradiol Ethanol Hexobendine NBMPR Pentoxifylline Progesterone Propentofylline

PMAT

Decynium-22

Enzyme (inhibitors)

XO

Allopurinol Amflutizole Benzbromarone Caffeic acid Cinnamaldehyde Cinnamomum osmophloeum Febuxostat Myo-inositol Kaempferol Myricetin Niraxostat Oxipurinol Phytic acid Pistacia integerrima Propolis Quercetin Tisopurine Topiroxostat

Others

Aminopterin Azathioprine Methotrexate Mycophenolic acid Pemetrexed Pralatrexate Many others

Others

Precursors: Adenine Adenosine AMP ADP ATP Cytosine Cytidine CMP CDP CTP Guanine Guanosine GMP GDP GTP Hypoxanthine Inosine IMP IDP ITP Ribose Uracil Uridine UMP UDP UTP

Others: Chrysophanol
Chrysophanol
(rhubarb)

See also: Receptor/signaling modulators

Authority control

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