CYTOSINE

Cytosine is one of several types of bases that are incorporated into the nucleic acid molecule. 

Cytosine is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine (uracil in RNA). 

Cytosine is a nitrogenous base derived from pyrimidine that occurs in nucleic acids, the heredity-controlling components of all living cells, and in some coenzymes, substances that act in conjunction with enzymes in chemical reactions in the body.

CAS Number: 71-30-7

EC Number: 200-749-5

Chemical formula: C4H5N3O

Molar mass: 111.10 g/mol

Synonyms: cytosine, 71-30-7, 4-Amino-2-hydroxypyrimidine, Cytosinimine, 2(1H)-Pyrimidinone, 4-amino-, 4-aminopyrimidin-2(1H)-one, 4-Amino-2(1H)-pyrimidinone, 6-Aminopyrimidin-2(1h)-One, 4-aminopyrimidin-2-ol, 6-amino-1H-pyrimidin-2-one, Cyt, MFCD00006034, 4-Amino-1H-pyrimidin-2-one, 4-amino-2-oxo-1,2-dihydropyrimidine, Cytosin, Zytosin, 2(1H)-pyrimidinone, 6-amino-, AI3-52281, UNII-8J337D1HZY, CHEBI:16040, 107646-83-3, 8J337D1HZY, 107646-84-4, 134434-39-2, 134434-40-5, 2(1H)-Pyrimidinone, 3,4-dihydro-4-imino-, (E)- (9CI), NSC-27787, 2-Pyrimidinol, 1,4-dihydro-4-imino-, (Z)- (9CI), 2(1H)-Pyrimidinone, 3,4-dihydro-4-imino-, (Z)- (9CI), SMR000857094, 4-amino-2-pyrimidinol, EINECS 200-749-5, NSC 27787, 2-Pyrimidinol, 4-amino-, aminopyrimidone, iminopyrimidinone, 3h-cytosine, Cytosine (8CI), 4-amino-1,2-dihydropyrimidin-2-one, Lamivudine impurity c, 287484-45-1, 66460-21-7, Cytosine-[15N2], Cytosine, >=99%, 2(1H)-Pyrimidinone, 4-amino- (9CI), Lamivudine impurity c rs, 4-amino-pyrimidin-2-ol, 4-Amino-2-oxypyrimidine, bmse000180, Epitope ID:167475, 4-Amino-2(1H)pyrimidone, EC 200-749-5, SCHEMBL4059, 4-Amino-2(1)-pyrimidone, DSSTox_CID_24456, DSSTox_RID_80242, 4-Amino-2(1H)-pyrimidone, DSSTox_GSID_44456, 2-Hydroxy-6-amino-pyrimidin, 4-amino-3h-pyrimidin-2-one, MLS001332635, MLS001332636, CHEMBL15913, 2-Pyrimidinol, 1,6-dihydro-6-imino-, (E)- (9CI), GTPL8490, 4-Aminopyrimidin-2-(1H)-one, DTXSID4044456, HMS2233N21, HMS3369N05, ZINC895210, Cytosine, >=99.0% (HPLC), ACT01668, ALBB-021996, BCP22793, HY-I0626, NSC27787, STR01426, Tox21_302139, s4893, STK366767, STL455080, 6-amino-1,2-dihydropyrimidin-2-one, AKOS000120336, AKOS005443393, AKOS015896942, AC-2489, AM83918, BCP9000005, CCG-266052, CS-W020703, MCULE-4426252594, 6-amino-1H-pyrimidin-2-one;CYTOSINE, CAS-71-30-7, CID 5274263, SRI-2354-05, 4-Aminopyrimidin-2(1H)-one (Cytosine), NCGC00247019-01, NCGC00255926-01, BP-20183, Cytosine, Vetec(TM) reagent grade, 99%, NCI60_012445, SY001643, 4-imino-3,4-dihydropyrimidin-2(1H)-one, DB-029615, FT-0617471, 71C307, C00380, J10203, 006C034, A837149, Q178425, CBA1D098-C5AB-46CE-AAC6-754572886EB2, Z256707830, Cytosine, United States Pharmacopeia (USP) Reference Standard, Cytosine, Pharmaceutical Secondary Standard; Certified Reference Material, Gemcitabine impurity A, European Pharmacopoeia (EP) Reference Standard, 2(1H)-Pyrimidinone, 6-amino-, 200-749-5, 2637, 4-amino-2-hydroxypyrimidine, 4-aminopyrimidin-2(1H)-one, 4-Aminopyrimidin-2-(1H)-one, 6-Amino-2(1H)-pyrimidinon, 6-Amino-2(1H)-pyrimidinone, 6-Amino-2(1H)-pyrimidinone, 6-Aminopyrimidin-2(1H)-on, 6-Aminopyrimidin-2(1H)-one, 71-30-7, Citosina, Cyt, Cytosin, Cytosine, Sitozin, 14419-77-3, 2 (1H)-Pyrimidinone, 4-amino-, 2(1H)-pyrimidinone, 3,4-dihydro-4-imino-, 2(1H)-Pyrimidinone, 3,4-dihydro-4-imino-, (Z)- (9CI), 2-oxy-4-amino pyrimidine, 2-Pyrimidinol, 1,4-dihydro-4-imino-, (Z)- (9CI), 2-Pyrimidinol, 1,6-dihydro-6-imino-, (E)- (9CI), 2-pyrimidinol, 4-amino-, 3h-cytosine, 3-Iodoimidazo[1,2-a]pyrimidine, 4-amino-1,2-dihydropyrimidin-2-one, 4-Amino-1H-pyrimidin-2-one, 4-Amino-2(1H)pyrimidone, 4-amino-2-oxo-1,2-dihydropyrimidine, 4-Amino-2-oxypyrimidine, 4-Amino-2-pyrimidinol, 4-amino-3H-pyrimidin-2-one, 4-aminopyrimidin-2-ol, 4-Aminouracil, 4-IMINO-1H-PYRIMIDIN-2-OL, 4-imino-3,4-dihydropyrimidin-2(1H)-one, 6-amino-1,2-dihydropyrimidin-2-one, 6-Amino-1H-pyrimidin-2-one, 6-amino-3-hydropyrimidin-2-one, 6-azanyl-1H-pyrimidin-2-one, 6-imino-1,6-dihydropyrimidin-2-ol, CID 5274263, Cytosine|Cytosine, Cytosinimine, MFCD00082220, missing, STR01426, Zytosin

Cytosine (symbol C or Cyt) is one of the four nucleobases found in DNA and RNA, along with adenine, guanine, and thymine (uracil in RNA). 

Cytosine 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, Cytosine forms three hydrogen bonds with guanine.

Cytosine (C) is one of the four nucleotide bases in DNA, with the other three being adenine (A), guanine (G) and thymine (T). 

Within a double-stranded DNA molecule, cytosine bases on one strand pair with guanine bases on the opposite strand. 

The sequence of the four nucleotide bases encodes DNA’s information.

Cytosine is a nitrogenous base derived from pyrimidine that occurs in nucleic acids, the heredity-controlling components of all living cells, and in some coenzymes, substances that act in conjunction with enzymes in chemical reactions in the body.

Cytosine is one of several types of bases that are incorporated into the nucleic acid molecule. 

Nucleic acids are composed of a five-carbon sugar bound to a phosphoric acid, along with a nitrogenous base. 

Deoxyribonucleic acid (DNA), the hereditary material of most living organisms, consists of the five-carbon sugar deoxyribose with a phosphate linkage, to which is attached cytosine or any of three other bases, which together form two complementary pairs. 

Cytosine’s complementary base in the DNA molecule is guanine.

Cytidine is a structural subunit of ribonucleic acid that consists of cytosine and the sugar ribose. 

Cytidine triphosphate (CTP), an ester of cytidine and triphosphoric acid, is Cytosine utilized in the cells to introduce cytidylic acid units into ribonucleic acids. 

CTP also reacts with nitrogen-containing alcohols to form coenzymes that participate in the formation of phospholipids.

Cytosine, also known as C, belongs to the class of organic compounds known as pyrimidones. 

Pyrimidones are compounds that contain a pyrimidine ring, which bears a ketone. 

Pyrimidine is a 6-membered ring consisting of four carbon atoms and two nitrogen centers at the 1- and 3- ring positions. 

Cytosine is also classified as 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). 

Cytosine is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine (uracil in RNA). 

The nucleoside of cytosine is cytidine. 

In Watson-Crick base pairing, cytosine forms three hydrogen bonds with guanine. 

Cytosine was discovered and named by Albrecht Kossel and Albert Neumann in 1894 when Cytosine was hydrolyzed from calf thymus tissues. 

Cytosine exists in all living species, ranging from bacteria to plants to humans. 

Within cells, cytosine can undergo several enzymatic reactions. 

Cytosine can be methylated into 5-methylcytosine by an enzyme called DNA methyltransferase (DNMT) or be methylated and hydroxylated to make 5-hydroxymethylcytosine. 

The DNA methyltransferase (DNMT) family of enzymes transfer a methyl group from S-adenosyl-l-methionine (SAM) to the 5‚Äô carbon of cytosine in a molecule of DNA. 

High levels of cytosine can be found in the urine of individuals with severe combined immunodeficiency syndrome (SCID). 

Cytosine concentrations as high as (23-160 mmol/mol creatinine) were detected in SCID patients compared to normal levels of <2 mmol/mol creatinine. When learning about DNA and RNA replication, nucleotides usually represent one of the first subjects introduced on the topic.  Cytosine constitutes one of the five nitrogenous bases (including adenine, thymine, guanine, and uracil), forming nucleic acid building blocks.  Also known by Cytosine IUPAC name, 6-amino-1H-pyrimidine-2-one, cytosine is one of three pyrimidine bases, with thymine and uracil constituting the remaining two.  Pyrimidine bases are smaller than their purine counterparts due to the presence of a single ring in their structures.  By contrast, purines contain two rings.  This difference in size allows pyrimidines to bond with purines and thus maintain a constant size throughout the double-stranded helices of DNA and RNA.  In order to form a base pair, the basic unit of double-stranded nucleic acids, cytosine must bond with Cytosine purine counterpart, guanine.  Aside from Cytosine role in creating nucleic acids, cytosine also possesses other significant functions within the cell. A pyrimidine base C4H5N3O that codes genetic information in the polynucleotide chain of DNA or RNA. 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).  Cytosine 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 Cytosine N1 nitrogen and the C1 position of the sugar, Cytosine 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 Cytosine 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. Cytosine is one of the five main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and RNA.  The other four nucleobases are adenine, guanine, thymine, and uracil.  Cytosine, thymine, and uracil are pyrimidine derivatives, while guanine and adenine are purine derivatives.  The nucleoside of cytosine is cytidine. In DNA, cytosine (C) and thymine (T) form hydrogen bonds with their complementary purine derivatives, guanine (G) and adenine (A).  In RNA, the complement of adenine is uracil (U)instead of thymine.  Thus, cytosine, along with adenine and guanine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA and uracil only in RNA. In Watson-Crick base pairing, cytosine forms three hydrogen bonds with guanine.  From the point of view of structure, Cytosine is remarkable that cytosine, with Cytosine three binding sites, only attaches to guanine in DNA, while adenine, with two sites for hydrogen binding, only attaches to thymine.  The way these hydrogen bonds hold the strands of the nucleic acid together to form the double helix, yet allowing the strands to "unzip" for replication and transcription, is simply amazing from a design point of view. Cytosine can also be a part of a nucleotide other than related to DNA or RNA.  As cytidine triphosphate (CTP), Cytosine can act as a co-factor to enzymes, and can transfer a phosphate to convert adenosine diphosphate (ADP) to adenosine triphosphate (ATP). Cytosine is a pyrimidine that has a heterocyclic aromatic ring.  In both DNA as well as RNA, Cytosine pairs with another base called guanine.  This is called complementary base pairing. Cytosine has an amine group at C4 and a keto group at the C2 position. 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.  Cytosine 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, Cytosine forms three hydrogen bonds with guanine. Cytosine was first discovered in 1894 when Cytosine 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. Cytosine can be found as part of DNA, RNA, or as a part of a nucleotide.  As cytidine triphosphate (CTP), Cytosine 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, Cytosine 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. Cytosine can also be methylated into 5-methylcytosine by an enzyme called DNA methyltransferase. Organic base of the pyrimidine family.  Cytosine was isolated from the nucleic acid of calf thymus tissue in 1894.  A suggested structure for cytosine, published in 1903, was confirmed in the same year when that base was synthesized in the laboratory.  Combined with the sugar ribose in glycosidic linkage, cytosine forms a derivative called cytidine (a nucleoside), which in turn can be phosphorylated with from one to three phosphoric acid groups, yielding the three nucleotides CMP (cytidine monophosphate), CDP (cytidine diphosphate), and CTP (cytidine triphosphate).  Analogous nucleosides and nucleotides are formed from cytosine and deoxyribose.  The nucleoside derivatives of cytosine perform important functions in cellular metabolism.  CTP acts as a coenzyme in both carbohydrate and lipid metabolism; Cytosine can readily donate one of Cytosine phosphate groups to adenosine diphosphate (ADP) to form adenosine triphosphate (ATP), an extremely important intermediate in the transfer of chemical energy in living systems.  CTP is the source of the cytidine found in ribonucleic acid (RNA) and deoxycytidine triphosphate (dCTP) is the source of the deoxycytidine in deoxyribonucleic acid (DNA).  Thus cytosine is intimately involved in the preservation and transfer of genetic information. Along with adenine, guanine, and thymine, cytosine is one of the four major bases present in DNA and RNA (uracil in RNA).  Cytosine a pyrimidine derivative with two substituents and a heterocyclic aromatic ring (an amine group at position 4 and a keto group at position 2).  Cytidine is the nucleoside of cytosine. Cytosine forms three hydrogen bonds with guanine in Watson-Crick base pairing. One of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine (uracil in RNA).  Cytosine reagent is used in a wide variety of research applications, as an enzyme substrate or precursor of effector molecules such as cytosine sugars. Cytosine, a nitrogenous base derived from pyrimidine that occurs in nucleic acids, the heredity-controlling components of all living cells, and in some coenzymes, substances that act in conjunction with enzymes in chemical reactions in the body. Cytosine is one of several types of bases that are incorporated into the nucleic acid molecule. Nucleic acids are composed of a five-carbon sugar bound to a phosphoric acid, along with a nitrogenous base. Deoxyribonucleic acid (DNA), the hereditary material of most living organisms, consists of the five-carbon sugar deoxyribose with a phosphate linkage, to which is attached cytosine or any of three other bases, which together form two complementary pairs. Cytosine’s complementary base in the DNA molecule is guanine. Cytidine is a structural subunit of ribonucleic acid that consists of cytosine and the sugar ribose. Cytidine triphosphate (CTP), an ester of cytidine and triphosphoric acid, is Cytosine utilized in the cells to introduce cytidylic acid units into ribonucleic acids. CTP also reacts with nitrogen-containing alcohols to form coenzymes that participate in the formation of phospholipids. Cytosine is an aminopyrimidine that is pyrimidin-2-one having the amino group located at position 4. Cytosine has a role as a human metabolite, an Escherichia coli metabolite, a Saccharomyces cerevisiae metabolite and a mouse metabolite. Cytosine is a pyrimidine nucleobase, a pyrimidone and an aminopyrimidine. Cytosine is a metabolite found in or produced by Escherichia coli. Cytosine is a natural product found in Streptomyces antibioticus, Salmonella enterica, and other organisms with data available. Cytosine vs. Thymine vs. Uracil: Cytosine, thymine, and uracil are pyrimidine nitrogenous bases. Cytosine can be differed from the other pyrimidines by having a keto group at position 2 and an amine group at position 4 in its heterocyclic aromatic ring. Cytosine has a chemical formula of C4H5N3O. Cytosine complementary pairs with guanine in both DNA and RNA as opposed to thymine and uracil that pairs up with adenine in DNA and RNA, respectively. Cytidine: Cytidine forms when cytosine attaches to a ribose ring (ribofuranose) via a beta-N1-glycosidic bond.  Cytidine represents the nucleoside of cytosine.  Unlike a nucleotide, which contains a nitrogenous base, a sugar, and a phosphate group, nucleosides consist only of a base and a sugar.  In addition to serving as an RNA component, cytidine represents a precursor for uridine, also utilized in RNA synthesis.  Aside from Cytosine role in RNA, cytidine is also vital for glutamate cycling and glutamate/glutamine levels in the brain. Application of Cytosine: Cytosine has been used: Cytosine is used for the preparation of nucleobase solutions Cytosine is used as a standard for high-performance liquid chromatography (HPLC) Cytosine is used for the estimation of global methylation rate Cytosine is used for nucleoside 5′-triphosphate (NTP) synthesis Cytosine is used in purification Uses of Cytosine: Cytosine is component of nucleic acids found throughout nature. Cytosine is used in biochemical research. Function of Cytosine: Cytosine is one of the five nitrogenous bases which make up the genetic code in DNA and RNA.  Nucleic acids play an essential role in heredity, cellular function, and biological reactions.  Cytosine can also be methylated by adding a methyl (CH3) group at the C5 position and, in this modified form, plays a vital role in epigenetics.  Moreover, cytosine can be transformed into other bases such as uracil, further elevating the importance of this nitrogenous base in the field of epigenetics.  Epigenetics is a relatively new field that examines the role of DNA modification in controlling gene expression in organisms.  In Cytosine epigenetically modified form, cytosine associates with changes in the cellular and developmental process, neuron cell development, and tumor development in humans.  When bound to three phosphate groups, cytosine forms the energy-carrying molecule cytidine triphosphate, or CTP, which can transfer phosphate groups and serve as a cofactor for enzymes. Biological Function: The other four primary (or canonical) nucleobases are thymine, uracil, guanine, and adenine.  Cytosine is one of the five primary (or canonical) nucleobases.  The genetic code is made up of these basic nucleobases.  The genetic code for a specific protein is contained in nucleic acids such as DNA and RNA molecules, which is dependent on the sequence of nucleobases. Nucleic acids play a crucial role in cellular functions, heredity, and organism survival.  Cytosine, in the form of cytidine triphosphate (CTP), may be used as an enzyme co-factor.  Cytosine can convert adenosine diphosphate (ADP) to ATP by transferring a phosphate.  ATP is a high-energy molecule that is involved in a variety of cellular functions and essential biological reactions. 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. 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 less understood. Common Biological Reactions of Cytosine: Pyrimidine biosynthesis differs from purine biosynthesis in a way that purines are synthesized as a nucleotide first whereas pyrimidines form initially as a free base. In humans, pyrimidines are synthesized in various tissues, especially in spleen, thymus, and gastrointestinal tract. Cytosine, similar to other pyrimidines, is formed from a series of steps, beginning with the formation of carbamoyl phosphate. Carbamoyl phosphate is produced from a reaction involving bicarbonate, glutamine, ATP, and water molecule. This process of forming carbamoyl phosphate is catalyzed by the enzyme carbamoyl phosphate synthetase. The carbamoyl phosphate is then converted into carbamoyl aspartate through the catalytic activity of aspartate transcarbamylase. Carbamoyl aspartate is next converted into dihydroorotate, which is then oxidized to produce orotate. 5-phospho-α-D-ribosyl 1-pyrophosphate (PRPP), a ribose phosphate, reacts to orotate to form orotidine-5-monophosphate (OMP). OMP is then converted into other pyrimidines. The enzyme OMP decarboxylase facilitates the decarboxylation of OMP to yield uridine monophosphate (UMP). Eventually, uridine diphosphate (UDP) and uridine triphosphate (UTP) are produced down the biosynthetic pathway by kinases and dephosphorylation of ATPs. UTP can be converted into cytidine triphosphate (CTP) by the amination of UTP via the enzyme CTP synthetase. Cytidine and deoxycytidine are nucleosides of cytosine. When phosphorylated with three phosphoric acid groups, they become cytidine triphosphate (CTP) and deoxycytidine triphosphate (dCTP), which are nucleotides that build up RNA and DNA molecules, respectively. The catabolism of pyrimidine nucleotide cytidine monophosphate (CMP) or cytosine ultimately leads to the formation of the by-products β-alanine, NH3 and CO2. The general degradation pathway is as follows: cytosine » uracil » N-carbamoyl- β-alanine » β-alanine, CO2, and ammonia. Nonetheless, cytosine may be recycled via the salvage pathway. For instance, cytosine may be converted into uracil by deamination. By uridine phosphorylase, uracil is converted into uridine by reacting with ribose-1-phosphate. Through the enzyme nucleoside kinase, uridine is converted into uridine monophosphate (UMP). Mutation is a change in the nucleotide sequence of a gene or a chromosome. A small-scale mutation characterized by a change of only one nucleotide base in the DNA or RNA molecule is called point mutation. Cytosine is relatively unstable. Cytosine may alter into uracil via spontaneous deamination. When this happens in DNA, repair mechanisms rectify the DNA sequence. For instance, uracil glycosylase removes by cleaving the cytosine-turned-uracil from the DNA. Then, the damaged region is removed and replaced using the other strand (i.e. the complementary strand) as the template. This type of repair is called base excision repair. Point mutations occurring in non-coding sequences often do not lead to discernible consequences. When coding sequences are involved, a single nucleotide alteration might lead to incorrect decoding during protein translation, especially when the mutation is left unrepaired. The altered structure of a protein may render the protein impaired by being dysfunctional or non-functional. Chemical reactions of Cytosine: Cytosine can be found as part of DNA, as part of RNA, or as a part of a nucleotide.  As cytidine triphosphate (CTP), Cytosine 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, Cytosine 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 or be methylated and hydroxylated to make 5-hydroxymethylcytosine.  The difference in rates of deamination of cytosine and 5-methylcytosine (to uracil and thymine) forms the basis of bisulfite sequencing. Properties of Cytosine: Cytosine has a chemical formula of C4H5N3O and molecular weight, or molar mass, of 111.10 g/mol.  The calculated density for cytosine is 1.55 g/cm3.  Cytosine has a relatively high melting point ranging from 320-325 °C.  Cytosine is a somewhat unstable molecule and can be deaminated to form uracil.  As a Bronsted base, cytosine can also act a hydrogen acceptor from acids. Cytosine is a pyrimidine derivative, with a heterocyclic, aromatic ring, and two substituents attached (an amine group at position four and a keto group at position two).  Heterocyclic compounds are organic compounds (those containing carbon) that contain a ring structure containing atoms in addition to carbon—such as sulfur, oxygen, or nitrogen—as part of the ring.  Aromaticity is a chemical property in which a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibit a stabilization stronger than would be expected by the stabilization of conjugation alone.  In organic chemistry, a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon. In DNA and RNA, cytosine is paired with guanine.  However, Cytosine 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. Cytosine is a pyrimidine derivative with two substituents and a heterocyclic, aromatic ring.  Organic compounds (those containing carbon) with a ring structure containing atoms with carbon, such as sulphur, oxygen, or nitrogen, as part of the ring are known as heterocyclic compounds.  Aromaticity is a chemical property in which the stability of a conjugated ring of unsaturated bonds, lone pairs, or empty orbitals is greater than can be predicted from conjugation alone.  A substituent is an atom or group of atoms that is substituted for a hydrogen atom on the parent chain of a hydrocarbon in organic chemistry. Cytosine is combined with guanine in DNA and RNA.  Cytosine is, however, not integrally stable and can degrade into uracil.  If the DNA repair enzymes, such as uracil glycosylase, which cleaves a uracil in DNA, do not restore Cytosine, a point mutation may occur. An enzyme called DNA methyltransferase can also methylate cytosine into 5-methylcytosine. Structure of Cytosine: Cytosine is a pyrimidine containing a single heterocyclic aromatic ring, a keto group at C2, and an amine group at C4.  The molecule is planar in shape.  Cytosine can form three hydrogen bonds with guanine.  Due to these three hydrogen bonds, the cytosine-guanine base pair has an overall higher boiling point and greater bond strength than the adenine-thymine base pair.  The high melting point makes the cytosine-guanine base-pair much more resistant to denaturation.  The double strand of DNA breaks down into Cytosine single constituent strands due to high temperatures. Cytosine is an aminopyrimidine with the amino group at position 4 and is pyrimidin-2-one.  Cytosine acts as a human metabolite, a metabolite in Escherichia coli, a metabolite in Saccharomyces cerevisiae, and a metabolite in mice.  Cytosine a pyrimidine nucleobase, pyrimidone, and aminopyrimidine all rolled into one.  The molecule has a planar shape, and in the DNA double helix, cytosine forms three hydrogen bonds with Guanine.  In RNA, which is made up of cytosine and ribose, the nucleoside of cytosine is cytidine.  Cytosine called deoxycytidine in DNA, and Cytosine made up of cytosine and deoxyribose.  The deoxycytidylate nucleotide of cytosine in DNA is made up of cytosine, ribose, and phosphate.  A heterocyclic aromatic ring, an amine group at C-4, and a keto group at C-2 make up cytosine. Purines and Pyrimidine Reaction of Cytosine: Purine biosynthesis differs from pyrimidine biosynthesis in that purines are formed first as a nucleotide, whereas pyrimidines are formed first as a free base. Pyrimidines are produced in a variety of tissues in humans, including the spleen, thymus, and gastrointestinal tract. Cytosine, like other pyrimidines, is made up of several steps, the first of which is the formation of carbamoyl phosphate. A reaction involving bicarbonate, glutamine, ATP, and a water molecule produces carbamoyl phosphate. The enzyme carbamoyl phosphate synthetase catalyses the formation of carbamoyl phosphate. The catalytic activity of aspartate transcarbamylase converts the carbamoyl phosphate to carbamoyl aspartate. Following that, carbamoyl aspartate is converted to dihydroorotate, which is then oxidised to yield orotate. The ribose phosphate 5-phospho—D-ribosyl 1-pyrophosphate (PRPP) reacts with orotate to form orotidine-5-monophosphate (OMP). After that, OMP is converted into other pyrimidines. OMP decarboxylase is an enzyme that aids in the decarboxylation of OMP to produce uridine monophosphate (UMP). Kinases and dephosphorylation of ATPs eventually generate uridine diphosphate (UDP) and uridine triphosphate (UTP) further down the biosynthetic pathway. By modification of UTP with the enzyme CTP synthetase, UTP can be converted to cytidine triphosphate (CTP). The nucleosides of cytosine are cytidine and deoxycytidine. They become cytidine triphosphate (CTP) and deoxycytidine triphosphate (dCTP), which are nucleotides that make up RNA and DNA molecules, respectively, when phosphorylated with three phosphoric acid groups. When the pyrimidine nucleotide cytidine monophosphate (CMP) or cytosine is catabolized, the by-products -alanine, ammonia, and carbon dioxide are created. The following is the general degradation pathway: cytosine » uracil » N-carbamoyl-alanine » -alanine, carbon dioxide, and ammonia. Cytosine, on the other hand, can be recycled via the salvage pathway. Deamination, for example, can transform cytosine to uracil. Uridine phosphorylase reacts with ribose-1-phosphate to convert uracil to uridine. Uridine is converted to uridine monophosphate by the enzyme nucleoside kinase (UMP). Tautomerization in Cytosine: Tautomerization occurs when cytosine switches from amino to imino functionality through intermolecular proton transfer. Chemical Activity of Cytosine: Guanine and Cytosine bind together by non-covalent hydrogen bonding at three different sites, as seen in the picture.  Cytosine worth noting that Watson and Crick first proposed that Guanine and Cytosine bonded by hydrogen bonding at two different sites. Cytosine is a nucleotide component that can be found in DNA and RNA.  Cytidine triphosphate is formed when the nucleoside cytidine binds to three phosphate groups (CTP).  This molecule serves as a cofactor for enzymes, assisting in the conversion of phosphate from adenosine diphosphate (ADP) to adenosine triphosphate (ATP) in order to prepare ATP for use in chemical reactions. Cytosine forms three hydrogen bonds with guanine in DNA and RNA.  This device, however, is unstable and can transform into uracil.  This is known as spontaneous deamination.  If DNA repair enzymes such as uracil glycosylase do not repair the damage by cleaving uracil in DNA, a point mutation may result. Theoretical aspects of Cytosine: Until October 2021, Cytosine had not been found in meteorites, which suggested the first strands of RNA and DNA had to look elsewhere to obtain this building block.  Cytosine likely formed within some meteorite parent bodies, however did not persist within these bodies due to an effective deamination reaction into uracil. In October 2021, Cytosine was announced as having been found in meteorites by researchers in a joint Japan/NASA project, that used novel methods of detection which avoided damaging nucleotides as they were extracted from meteorites. Biochem/physiol Actions of Cytosine: Cytosine (C) is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine (uracil in RNA). Cytosine is a pyrimidine, which forms three hydrogen bonds to base pair with guanine.  Cytosine forms a nucleotide cytidine, that is phosphorylated to cytidine 5′ monophosphate (CMP), cytidine 5′ diphosphate (CDP) and cytidine 5′ triphosphate (CTP). Pharmacology and Biochemistry of Cytosine: Human Metabolite Information: Tissue Locations: Blood Epidermis Fibroblasts Intestine Neuron Placenta Prostate Skeletal Muscle Spleen Testis Cellular Locations: Extracellular History of Cytosine: Cytosine was discovered and named by Albrecht Kossel and Albert Neumann in 1894 when Cytosine 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 1998, cytosine was used in an early demonstration of quantum information processing when Oxford University researchers implemented the 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 Cytosine origin is unknown. Cytosine was first discovered in 1894 when Cytosine was isolated from calf thymus tissues.  Cytosine recently found use in quantum computation. The first time any quantum mechanical properties were harnessed to process information took place on August 1st, 1998, when researchers at Oxford implemented David Deutsch's algorithm on a two cubit NMRQC (Nuclear Magnetic Resonance Quantum Computer) based on the cytosine molecule. Etymology of Cytosine: After German Cytosin, equivalent to Ancient Greek κύτος (kútos) + -ine.  Cytosine was discovered and named by the German biochemists Albrecht Kossel and Albert Neumann in 1894 when Cytosine was hydrolyzed from calf thymus tissues. Handling and storage of Cytosine: Storage conditions: Tightly closed. Dry. Storage class: Storage class (TRGS 510): 11: Combustible Solids Stability and reactivity of Cytosine: Reactivity: The following applies in general to flammable organic substances and mixtures: in correspondingly fine distribution, when whirled up a dust explosion potential may generally be assumed. Chemical stability: Cytosine is chemically stable under standard ambient conditions (room temperature). Incompatible materials: Strong oxidizing agents, Strong acids First aid measures of Cytosine: If inhaled: After inhalation: Fresh air. In case of skin contact: Take off immediately all contaminated clothing. Rinse skin with water/ shower. In case of eye contact: After eye contact: Rinse out with plenty of water. Remove contact lenses. If swallowed: After swallowing: Make victim drink water (two glasses at most). Consult doctor if feeling unwell. Firefighting measures of Cytosine: Suitable extinguishing media: Water Foam Carbon dioxide (CO2) Dry powder Unsuitable extinguishing media: For Cytosine no limitations of extinguishing agents are given. Special hazards arising from Cytosine: Carbon oxides Nitrogen oxides (NOx) Combustible. Development of hazardous combustion gases or vapours possible in the event of fire. Advice for firefighters: In the event of fire, wear self-contained breathing apparatus. Further information: Suppress (knock down) gases/vapors/mists with a water spray jet. Prevent fire extinguishing water from contaminating surface water or the ground water system. Accidental release measures of Cytosine: Personal precautions, protective equipment and emergency procedures: Advice for non-emergency personnel: Avoid inhalation of dusts. Evacuate the danger area, observe emergency procedures, consult an expert. Environmental precautions: Do not let product enter drains. Methods and materials for containment and cleaning up: Cover drains. Collect, bind, and pump off spills.  Observe possible material restrictions. Take up dry. Dispose of properly. Clean up affected area. Avoid generation of dusts. Identifiers of Cytosine: CAS Number: 71-30-7 ChEBI: CHEBI:16040 ChEMBL: ChEMBL15913 ChemSpider: 577 ECHA InfoCard: 100.000.681 KEGG: C00380 MeSH: Cytosine PubChem CID: 597 UNII: 8J337D1HZY CompTox Dashboard (EPA): DTXSID4044456 InChI: InChI=1S/C4H5N3O/c5-3-1-2-6-4(8)7-3/h1-2H,(H3,5,6,7,8) Key: OPTASPLRGRRNAP-UHFFFAOYSA-N check InChI=1/C4H5N3O/c5-3-1-2-6-4(8)7-3/h1-2H,(H3,5,6,7,8) Key: OPTASPLRGRRNAP-UHFFFAOYAY SMILES: O=C1Nccc(N)n1 Synonym(s): 4-Amino-2-hydroxypyrimidine, 4-Aminopyrimidin-2-(1H)-one Empirical Formula (Hill Notation): C4H5N3O CAS Number: 71-30-7 Molecular Weight: 111.10 Beilstein: 2637 EC Number: 200-749-5 MDL number: MFCD00006034 PubChem Substance ID: 24892620 NACRES: NA.51 Properties of Cytosine: Chemical formula: C4H5N3O Molar mass: 111.10 g/mol Density: 1.55 g/cm3 (calculated) Melting point: 320 to 325 °C (608 to 617 °F; 593 to 598 K) (decomposes) Acidity (pKa): 4.45 (secondary), 12.2 (primary) Magnetic susceptibility (χ): -55.8·10−6 cm3/mo biological source: synthetic (organic) Quality Level: 200 Assay: ≥99% form: powder mp: >300 °C (lit.)

solubility: 0.5 M HCl: 50 mg/mL, clear to very slightly hazy, colorless to faintly yellow

SMILES string: NC1=NC(=O)NC=C1

InChI: 1S/C4H5N3O/c5-3-1-2-6-4(8)7-3/h1-2H,(H3,5,6,7,8)

InChI key: OPTASPLRGRRNAP-UHFFFAOYSA-N

Molecular Weight: 111.10

XLogP3: -1.7

Hydrogen Bond Donor Count: 2

Hydrogen Bond Acceptor Count: 2

Rotatable Bond Count: 0

Exact Mass: 111.043261792

Monoisotopic Mass: 111.043261792

Topological Polar Surface Area: 67.5 Ų

Heavy Atom Count: 8

Complexity: 170

Isotope Atom Count: 0

Defined Atom Stereocenter Count: 0

Undefined Atom Stereocenter Count: 0

Defined Bond Stereocenter Count: 0

Undefined Bond Stereocenter Count: 0

Covalently-Bonded Unit Count: 1

Compound Is Canonicalized: Yes

Names of Cytosine:

Preferred IUPAC name:

4-Aminopyrimidin-2(1H)-one

Other names:

4-Amino-1H-pyrimidine-2-one