Thymine

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For the similarly spelled B vitamin, see Thiamine.
Thymine
Names
IUPAC name
5-Methylpyrimidine-2,4(1H,3H)-dione
Other names
5-methyluracil
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.560 Edit this at Wikidata
MeSH Thymine
UNII
  • InChI=1S/C5H6N2O2/c1-3-2-6-5(9)7-4(3)8/h2H,1H3,(H2,6,7,8,9) ☒N
    Key: RWQNBRDOKXIBIV-UHFFFAOYSA-N ☒N
  • InChI=1/C5H6N2O2/c1-3-2-6-5(9)7-4(3)8/h2H,1H3,(H2,6,7,8,9)
    Key: RWQNBRDOKXIBIV-UHFFFAOYAL
  • Cc1c[nH]c(=O)[nH]c1=O
Properties
C5H6N2O2
Molar mass 126.115 g·mol−1
Density 1.23 g cm−3 (calculated)
Melting point 316 °C (601 °F; 589 K)
Boiling point 335 °C (635 °F; 608 K)
Acidity (pKa) 9.7
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Thymine /ˈ[invalid input: 'th']aɪm[invalid input: 'i-']n/ (T, Thy) 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 (from calves' thymus glands) in 1893 by Albrecht Kossel and Albert Neumann.[1]

Derivation

As the name suggests, thymine may be derived by methylation of uracil at the 5th carbon. In RNA, thymine is replaced with uracil in most cases. In DNA, thymine (T) binds to adenine (A) via two hydrogen bonds, thus stabilizing the nucleic acid structures.

Thymine combined with deoxyribose creates the nucleoside deoxythymidine, which is synonymous with the term thymidine. Thymidine can be phosphorylated with one, two, or three phosphoric acid groups, creating, respectively, TMP, TDP, or TTP (thymidine mono-, di-, or triphosphate).

One of the common mutations of DNA involves two adjacent thymines or cytosine, which, in presence of ultraviolet light, may form thymine dimers, causing "kinks" in the DNA molecule that inhibit normal function.

Thymine could also be a target for actions of 5-fluorouracil (5-FU) in cancer treatment. 5-FU can be a metabolic analog of thymine (in DNA synthesis) or uracil (in RNA synthesis). Substitution of this analog inhibits DNA synthesis in actively dividing cells.

Thymine bases are frequently oxidized to hydantoins over time after the death of an organism.[2]

Thymine is a nuclear base.

See also

References

  1. ^ Albrecht Kossel and Albert Neumann (1893) "Ueber das Thymin, ein Spaltungsproduct der Nucleïnsäure" (On thymine, a cleavage product of nucleic acid), Berichte der Deutschen Chemischen Gesellschaft zu Berlin, 26 : 2753-2756. From p. 2754: "Wir bezeichnen diese Substanz als Thymin." (We designate this substance as "thymine" [because it was initially obtained from the thymus glands of calves].)
  2. ^ Hofreiter M., Serre D., Poinar H.N., Kuch M., and Paabo S. Nature Reviews Genetics (2001) 2:353.

External links

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