Cytosine (redirected from cytosine arabinoside)

cytosine (sī`tōsēn'), organic base of the pyrimidine family. It 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; it can readily donate one of its 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.

---

cytosine

Organic compound of the pyrimidine family, often called a base, consisting of a single ring, containing both nitrogen and carbon atoms, and an amino group. It occurs in combined form in nucleic acids and several coenzymes. In DNA its complementary base is guanine. It or its corresponding nucleoside or nucleotide may be prepared from DNA by selective techniques of hydrolysis.

---

cytosine [′sīd·ə‚sēn]

(biochemistry)

C₄H₅ON₃A pyrimidine occurring as a fundamental unit or base of nucleic acids.

---

Cytosine 

(also 2-hydroxy-6-aminopyrimidine), a natural organic compound. A pyrimidine base, cytosine occurs as white crystals or thin, lustrous platelets. Its molecular weight is 111.1. It is found in all living cells as a component of nucleotides—that is, compounds that form nucleic acids, coenzymes, and certain other biologically active substances. The nucleoside cytidine consists of cytosine and the carbohydrate D-ribose.