Thymidine 89216 219639056 2008-06-16T05:15:07Z PlankBot 7310603 Robot-assisted disambiguation: Powder - Changed link(s) to [[Powder (substance)]] {{Chembox new |ImageFile=DT chemical structure.png |ImageSize= |IUPACName= |OtherNames= |Section1= {{Chembox Identifiers | CASNo=50-89-5 | PubChem=1134 | SMILES=CC1=CN(C(=O)NC1=O)C2CC(C(O2)CO)O | MeSHName=Thymidine }} |Section2= {{Chembox Properties | Formula=C<sub>10</sub>H<sub>14</sub>N<sub>2</sub>O<sub>5</sub> | MolarMass=242.229 | Appearance= | Density= | MeltingPt= | BoilingPt= | Solubility= }} |Section3= {{Chembox Hazards | MainHazards= | FlashPt= | Autoignition= }} }} '''Thymidine''' (more precisely called '''deoxythymidine'''; can also be labelled '''deoxyribosylthymine''', and '''thymine deoxyriboside''') is a [[chemical]] [[Chemical compound|compound]], more precisely a [[pyrimidine]] [[deoxynucleoside]]. Deoxythymidine is the [[DNA]] nucleoside T, which pairs with deoxyadenosine (A) in double-stranded DNA. In cell biology it is used to synchronize the cells in S phase. ==Structure and properties== In its composition, deoxythymidine is [[deoxyribose]] (a pentose [[sugar]]) joined to the [[pyrimidine]] base [[thymine]]. Deoxythymidine can be phosphorylated with one, two or three phosphoric acid groups, creating respectively dTMP, dTDP or dTTP ((deoxy)thymidine mono- di- or triphosphate). It exists in [[solid]] form as small white [[crystals]] or white crystalline [[Powder (substance)|powder]], has a [[molecular weight]] of 242.229 [[unified atomic mass unit|u]], and has a [[melting point]] of 185 [[degrees Celsius|°C]]. The stability of deoxythymidine under [[standard temperature and pressure]] (STP) is very high. Deoxythymidine is non-toxic and as part of one of the four nucleotides in DNA it is a naturally occurring compound that exists in all living organisms and DNA viruses. RNA has uridine (uracil joined to ribose) instead. Uracil is chemically very similar to thymine, the latter being 5-methyluracil. Since thymine nucleotides are precursors of DNA, not RNA, the prefix "deoxy" is often left out, i.e., deoxythymidine is often just called thymidine. ==Modified analogs of thymidine== [[Iododeoxyuridine]] is a radiosensitizer and increases the amount of DNA damage received from ionizing radiation. [[Azidothymidine]] (AZT) - used in the treatment of [[HIV]] infection. AZT [[Reverse transcriptase inhibitor|inhibits the process of reverse transcription]], a critical step in the [[HIV#Replication_cycle|viral life cycle]]. [[tritium|Tritiated]] thymidine is commonly used in cell proliferation assays. The thymidine is incorporated into dividing cells and the level of this incorporation, measured using a liquid scintillation counter, is proportional to the amount of cell proliferation. [[Bromodeoxyuridine]] (BrdU) is another thymidine analog that is often used for the detection of proliferating cells in living tissues. ==External links== {{Nucleobases, nucleosides, and nucleotides}} [[Category:Nucleosides]] [[de:Thymidin]] [[es:Timidina]] [[fr:Désoxythymidine]] [[it:Timidina]] [[lt:Timidinas]] [[ja:チミジン]] [[pl:Tymidyna]] [[pt:Timidina]] [[zh:胸苷]]