Thymine

For the similarly spelled B vitamin, see Thiamine.
Thymine
Names
IUPAC name
5-Methylpyrimidine-2,4(1H,3H)-dione
Other names
5-methyluracil
Identifiers
65-71-4 Y
ChEBI CHEBI:17821 N
ChEMBL ChEMBL993 N
ChemSpider 1103 N
4581
Jmol 3D model Interactive image
MeSH Thymine
PubChem 1135
UNII QR26YLT7LT Y
Properties
C5H6N2O2
Molar mass 126.12 g·mol−1
Density 1.23 g cm−3 (calculated)
Melting point 316 to 317 °C (601 to 603 °F; 589 to 590 K)
Boiling point 335 °C (635 °F; 608 K) (decomposes)
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 YN ?)
Infobox references

Thymine /ˈθmn/ (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.

    Derivation

    As its alternate name (5-methyluracil) 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, thereby 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.

    Thymine is a nuclear base.

    Theoretical aspects

    In March 2015, NASA scientists reported that, for the first time, complex DNA and RNA organic compounds of life, including uracil, cytosine and thymine, have been formed in the laboratory under outer space conditions, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like polycyclic aromatic hydrocarbons (PAHs), the most carbon-rich chemical found in the Universe, may have been formed in red giants or in interstellar dust and gas clouds, according to the scientists.

    See also

    References

    External links

    • Thymine MS Spectrum
    • Infoplease Encyclopedia
    • Science Aid: DNA Structure and Replication
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