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Thymidine 3D ball.png
Other names
Td, 1-[(2R,4S,5R)-4-Hydroxy-5-(hydroxymethyl)tetrahydrofur-2-yl]-5-methyl-1,3-dihydropyrimidine-2,4-dione
3D model (JSmol)
ECHA InfoCard 100.000.065
MeSH Thymidine
PubChem CID
Molar mass 242.231 g·mol−1
Melting point 185 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Thymidine (deoxythymidine; other names deoxyribosylthymine, thymine deoxyriboside) is 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 G1/early S phase.

Pyrimidine is an aromatic heterocyclic organic compound similar to pyridine. One of the three diazines, it has the nitrogen atoms at positions 1 and 3 in the ring. The other diazines are pyrazine and pyridazine. In nucleic acids, three types of nucleobases are pyrimidine derivatives: cytosine (C), thymine (T), and uracil (U).

Nucleoside glycosylamine that can be thought of as nucleotide without a phosphate group

Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase and a five-carbon sugar, whereas a nucleotide is composed of a nucleobase, a five-carbon sugar, and one or more phosphate groups. In a nucleoside, the anomeric carbon is linked through a glycosidic bond to the N9 of a purine or the N1 of a pyrimidine. Examples of nucleosides include cytidine, uridine, adenosine, guanosine, thymidine and inosine.

DNA Molecule that encodes the genetic instructions used in the development and functioning of all known organisms and many viruses

Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids; alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.


Before the boom in thymidine use caused by the need for thymidine in the production of the antiretroviral drug azidothymidine (AZT), much of the world's thymidine production came from herring sperm. [1] Thymidine occurs almost exclusively in DNA but it also occurs in the T-loop of tRNA.

Zidovudine chemical compound

Zidovudine (ZDV), also known as azidothymidine (AZT), is an antiretroviral medication used to prevent and treat HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used to prevent mother-to-child spread during birth or after a needlestick injury or other potential exposure. It is sold both by itself and together as lamivudine/zidovudine and abacavir/lamivudine/zidovudine. It can be used by mouth or by slow injection into a vein.

Herring forage fish, mostly belonging to the family Clupeidae

Herring are forage fish, mostly belonging to the family Clupeidae.

T arm Region of the RNA

The T-arm or T-loop is a specialized region on the tRNA molecule which acts as a special recognition site for the ribosome to form a tRNA-ribosome complex during protein biosynthesis or translation (biology).

Structure and properties

In its composition, deoxythymidine is a nucleoside composed of deoxyribose (a pentose sugar) joined to the pyrimidine base thymine.

Deoxyribose, or more precisely 2-deoxyribose, is a monosaccharide with idealized formula H−(C=O)−(CH2)−(CHOH)3−H. Its name indicates that it is a deoxy sugar, meaning that it is derived from the sugar ribose by loss of an oxygen atom. Since the pentose sugars arabinose and ribose only differ by the stereochemistry at C2′, 2-deoxyribose and 2-deoxyarabinose are equivalent, although the latter term is rarely used because ribose, not arabinose, is the precursor to deoxyribose.

Sugar generic name for sweet-tasting, soluble carbohydrates

Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. The various types of sugar are derived from different sources. Simple sugars are called monosaccharides and include glucose, fructose, and galactose. "Table sugar" or "granulated sugar" refers to sucrose, a disaccharide of glucose and fructose. In the body, sucrose is hydrolysed into fructose and glucose.

Thymine Chemical compound of DNA

Thymine is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. In RNA, thymine is replaced by the nucleobase uracil. Thymine was first isolated in 1893 by Albrecht Kossel and Albert Neumann from calves' thymus glands, hence its name.

Deoxythymidine can be phosphorylated with one, two or three phosphoric acid groups, creating dTMP (deoxythymidine monophosphate), dTDP, or dTTP (for the di- and tri- phosphates, respectively).

It exists in solid form as small white crystals or white crystalline powder. It has a molecular weight of 242.229  u and a melting point of 185  °C. The stability of deoxythymidine under standard temperature and pressure (STP) is very high.

Solid solid object

Solid is one of the four fundamental states of matter. In solids particles are closely packed. It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a gas does. The atoms in a solid are tightly bound to each other, either in a regular geometric lattice or irregularly. Solids cannot be compressed with little pressure whereas gases can be compressed with little pressure because in gases molecules are loosely packed.

Melting point temperature at which a solid turns liquid

The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.

Deoxythymidine is non-toxic and as part of one of the four nucleosides in DNA it is a naturally occurring compound that exists in all living organisms and DNA viruses. Instead of thymidine, RNA contains uridine (uracil joined to ribose). Uracil is chemically very similar to thymine, which is also known as 5-methyluracil. Since thymine nucleotides are precursors of DNA (but not RNA), the prefix "deoxy" is often left out, i.e., deoxythymidine is often just called thymidine.

Uridine chemical compound

Uridine is a glycosylated pyrimidine-analog containing uracil attached to a ribose ring (or more specifically, a ribofuranose) via a β-N1-glycosidic bond.

Uracil Chemical compound of RNA

Uracil is one of the four nucleobases in the nucleic acid of RNA that are represented by the letters A, G, C and U. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine. Uracil is a demethylated form of thymine.

Ribose is a carbohydrate with the formula C5H10O5; specifically, it is a pentose monosaccharide (simple sugar) with linear form H−(C=O)−(CHOH)4−H, which has all the hydroxyl groups on the same side in the Fischer projection.

Thymidine is listed as a chemical teratogen. [2]

Modified analogs

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 inhibits the process of reverse transcription, a critical step in the viral life cycle.

Radiolabeled thymidine (TdR), such as tritiated thymidine (3H-TdR), 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. For example, lymphocyte proliferation can be measured this way in lymphoproliferative disorders.

Bromodeoxyuridine (BrdU) is another thymidine analog that is often used for the detection of proliferating cells in living tissues.

5-Ethynyl-2´-deoxyuridine (EdU) is a thymidine analog which is incorporated into the DNA of dividing cells and is used to assay DNA synthesis in cell culture or living tissues. It can be visualized by covalently binding a fluorescent azide using click chemistry, which is less harsh than the conditions used to expose the epitope for BrdU antibodies.

Edoxudine is an antiviral drug.

Related Research Articles

Base pair unit consisting of two nucleobases bound to each other by hydrogen bonds: either adenine–thymine or guanine–cytosine in natural DNA (additional types occur in RNA)

A base pair (bp) is a unit consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA and RNA. Dictated by specific hydrogen bonding patterns, Watson–Crick base pairs allow the DNA helix to maintain a regular helical structure that is subtly dependent on its nucleotide sequence. The complementary nature of this based-paired structure provides a redundant copy of the genetic information encoded within each strand of DNA. The regular structure and data redundancy provided by the DNA double helix make DNA well suited to the storage of genetic information, while base-pairing between DNA and incoming nucleotides provides the mechanism through which DNA polymerase replicates DNA and RNA polymerase transcribes DNA into RNA. Many DNA-binding proteins can recognize specific base-pairing patterns that identify particular regulatory regions of genes.

Cytosine Chemical compound of DNA and RNA

Cytosine is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached. The nucleoside of cytosine is cytidine. In Watson-Crick base pairing, it forms three hydrogen bonds with guanine.

Nucleobase nitrogen-containing biological compounds that form nucleosides

Nucleobases, also known as nitrogenous bases or often simply bases, are nitrogen-containing biological compounds that form nucleosides, which in turn are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids. The ability of nucleobases to form base pairs and to stack one upon another leads directly to long-chain helical structures such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).

Ribonucleotide chemical compound

In biochemistry, a ribonucleotide is a nucleotide containing ribose as its pentose component. It is considered a molecular precursor of nucleic acids. Nucleotides are the basic building blocks of DNA and RNA. The monomer itself from ribonucleotides forms the basic building blocks for RNA. However, the reduction of ribonucleotide, by enzyme ribonucleotide reductase (RNR), forms deoxyribonucleotide, which is the essential building block for DNA. There are several differences between DNA deoxyribonucleotides and RNA ribonucleotides. Successive nucleotides are linked together via phosphodiester bonds by 3'-5'.

A salvage pathway is a pathway in which nucleotides are synthesized from intermediates in the degradative pathway for nucleotides.

Thymidine kinase InterPro Family

Thymidine kinase is an enzyme, a phosphotransferase : 2'-deoxythymidine kinase, ATP-thymidine 5'-phosphotransferase, EC It can be found in most living cells. It is present in two forms in mammalian cells, TK1 and TK2. Certain viruses also have genetic information for expression of viral thymidine kinases. Thymidine kinase catalyzes the reaction:

A nitrogenous base, or nitrogen-containing base, is an organic molecule with a nitrogen atom that has the chemical properties of a base. The main biological function of a nitrogenous base is to bond nucleic acids together. A nitrogenous base owes its basic properties to the lone pair of electrons of a nitrogen atom.

Thymidine monophosphate anion

Thymidine monophosphate (TMP), also known as thymidylic acid, deoxythymidine monophosphate (dTMP), or deoxythymidylic acid, is a nucleotide that is used as a monomer in DNA. It is an ester of phosphoric acid with the nucleoside thymidine. dTMP consists of a phosphate group, the pentose sugar deoxyribose, and the nucleobase thymine. Unlike the other deoxyribonucleotides, thymidine monophosphate often does not contain the "deoxy" prefix in its name; nevertheless, its symbol often includes a "d" ("dTMP"). Dorland’s Illustrated Medical Dictionary provides an explanation of the nomenclature variation at its entry for thymidine.

Thymidine diphosphate chemical compound

Thymidine diphosphate (TDP) or deoxythymidine diphosphate (dTDP) is a nucleotide diphosphate. It is an ester of pyrophosphoric acid with the nucleoside thymidine. dTDP consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase thymine. Unlike the other deoxyribonucleotides, thymidine diphosphate does not always contain the "deoxy" prefix in its name.

An antimetabolite is a chemical that inhibits the use of a metabolite, which is another chemical that is part of normal metabolism. Such substances are often similar in structure to the metabolite that they interfere with, such as the antifolates that interfere with the use of folic acid; thus, competitive inhibition can occur, and the presence of antimetabolites can have toxic effects on cells, such as halting cell growth and cell division, so these compounds are used as chemotherapy for cancer.

Nucleoside analogues are nucleosides which contain a nucleic acid analogue and a sugar. Nucleotide analogs are nucleotides which contain a nucleic acid analogue, a sugar, and one to three phosphate groups.

Floxuridine chemical compound

Floxuridine is an oncology drug that belongs to the class known as antimetabolites. Specifically, floxuridine is a pyrimidine analog, classified as a deoxyuridine. The drug is usually administered via an artery, and most often used in the treatment of colorectal cancer. The quality of life and survival rates of individuals that receive continuous hepatic artery infusion of floxuridine for colorectal cancer metastases is significantly higher than control groups. Floxuridine can also be prescribed for the treatment of kidney and stomach cancers. In vitro uses of floxuridine include 5-minute treatments of fluorouracil, floxuridine, and mitomycin to increase cell proliferation in Tenon's capsule fibroblasts.

Bromodeoxyuridine chemical compound

Bromodeoxyuridine is a synthetic nucleoside that is an analog of thymidine. BrdU is commonly used in the detection of proliferating cells in living tissues. 5-Bromodeoxycytidine is deaminated to form BrdU.

Nucleic acid metabolism

Nucleic acid metabolism is the process by which nucleic acids are synthesized and degraded. Nucleic acids are polymers of nucleotides. Nucleotide synthesis is an anabolic mechanism generally involving the chemical reaction of phosphate, pentose sugar, and a nitrogenous base. Destruction of nucleic acid is a catabolic reaction. Additionally, parts of the nucleotides or nucleobases can be salvaged to recreate new nucleotides. Both synthesis and degradation reactions require enzymes to facilitate the event. Defects or deficiencies in these enzymes can lead to a variety of diseases.

Thymidine phosphorylase InterPro Family

In enzymology, a thymidine phosphorylase is an enzyme that catalyzes the chemical reaction

NT5M protein-coding gene in the species Homo sapiens

5',3'-nucleotidase, mitochondrial, also known as 5'(3')-deoxyribonucleotidase, mitochondrial (mdN) or deoxy-5'-nucleotidase 2 (dNT-2), is an enzyme that in humans is encoded by the NT5M gene. This gene encodes a 5' nucleotidase that localizes to the mitochondrial matrix. This enzyme dephosphorylates the 5'- and 2'(3')-phosphates of uracil and thymine deoxyribonucleotides. The gene is located within the Smith-Magenis syndrome region on chromosome 17.

Janet Rideout is an organic chemist and one of the scientists who discovered that azidothymidine (AZT) could be used as an antiretroviral agent to treat Human Immunodeficiency Virus (HIV). She also played a key role in the development of acyclovir, the first effective treatment for herpes simplex virus.


  1. Makoto Ishii; Hideyuki Shirae; Kenzo Yokozeko, Enzymatic Production of 5-Methyluridine from Purine Nucleosides and Thymine by Erwinia carotovora AJ-2992, Agricultural and Biological Chemistry
  2. The following list of chemicals known or believed to be teratogens is drawn primarily from Dangerous Properties of Industrial Materials, 7th Ed., by N. Irving Sax and Richard J. Lewis.