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Wikipedia

Thymine

February 15, 2024

For the B vitamin whose name sounds and looks similar, see Thiamine.
Not to be confused with thymidine.

Thymine (/ˈθaɪmɪn/) (symbol T or 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 in 1893 by Albrecht Kossel and Albert Neumann from calf thymus glands, hence its name.[2]

Thymine
Names
Preferred IUPAC name
5-Methylpyrimidine-2,4(1H,3H)-dione
Other names
5-Methyluracil
Identifiers
  • 65-71-4 Y
3D model (JSmol)
  • Interactive image
ChEBI
  • CHEBI:17821 Y
ChEMBL
  • ChEMBL993 Y
ChemSpider
  • 1103 Y
ECHA InfoCard 100.000.560
  • 4581
MeSH Thymine
  • 1135
UNII
  • QR26YLT7LT Y
  • DTXSID4052342
  • InChI=1S/C5H6N2O2/c1-3-2-6-5(9)7-4(3)8/h2H,1H3,(H2,6,7,8,9) Y
    Key: RWQNBRDOKXIBIV-UHFFFAOYSA-N Y
  • O=C1NC(=O)NC=C1C
Properties
C5H6N2O2
Molar mass 126.115 g·mol−1
Density 1.223 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)
3.82 g/L[1]
Acidity (pKa) 9.7
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Derivation edit

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 up to three phosphoric acid groups, producing dTMP (deoxythymidine monophosphate), dTDP, or dTTP (for the di- and tri- phosphates, respectively).

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.[3]

Thymine imbalance causes mutation edit

During growth of bacteriophage T4, an imbalance of thymine availability, either a deficiency or an excess of thymine, causes increased mutation.[4] The mutations caused by thymine deficiency appear to occur only at AT base pair sites in DNA and are often AT to GC transition mutations.[5] In the bacterium Escherichia coli, thymine deficiency was also found to be mutagenic and cause AT to GC transitions.[6]

Theoretical aspects edit

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), another carbon-rich compound, may have been formed in red giants or in interstellar dust and gas clouds, according to the scientists.[7] Thymine has not been found in meteorites, which suggests the first strands of DNA had to look elsewhere to obtain this building block. Thymine likely formed within some meteorite parent bodies, but may not have persisted within these bodies due to an oxidation reaction with hydrogen peroxide.[8]

Synthesis edit

Laboratory synthesis edit

Thymine was first prepared by hydrolysis of the corresponding nucleoside obtained from natural sources. Interest in its direct chemical synthesis began in the early 1900s: Emil Fischer published a method starting from urea but a more practical synthesis used methylisothiourea in a condensation reaction with ethyl formyl propionate, followed by hydrolysis of the pyrimidine intermediate:[9]

 

Many other preparative methods have been developed, including optimised conditions so that urea can be used directly in the reaction shown above, preferably with methyl formyl propionate.[10]

See also edit

References edit

  1. ^ Dannenfelser, R.-M.; Yalkowsky, S.H. (December 1991). "Data base of aqueous solubility for organic non-electrolytes". Science of the Total Environment. 109–110 (C): 625–628. Bibcode:1991ScTEn.109..625D. doi:10.1016/0048-9697(91)90214-Y. Retrieved 2021-11-14.
  2. ^ Albrecht, Kossel; Neumann, Albert (Oct–Dec 1893). "Ueber das Thymin, ein Spaltungsproduct der Nucleïnsäure" [On thymine, a cleavage product of nucleic acid]. Berichte der Deutschen Chemischen Gesellschaft. 26 (3): 2753–2756. doi:10.1002/cber.18930260379. Retrieved 2021-11-14. p. 2754: Wir bezeichnen diese Substanz als Thymin. [We designate this substance as thymine.]
  3. ^ Hofreiter, Michael; Serre, David; Poinar, Henrik N.; Kuch, Melanie; Pääbo, Svante (2001-05-01). "Ancient DNA". Nature Reviews Genetics. 2 (5): 353–359. doi:10.1038/35072071. PMID 11331901. S2CID 205016024.
  4. ^ Bernstein, Carol; Bernstein, Harris; Mufti, Siraj; Strom, Barbara (October 1972). "Stimulation of mutation in phage T 4 by lesions in gene 32 and by thymidine imbalance". Mutat. Res. 16 (2): 113–119. doi:10.1016/0027-5107(72)90171-6. PMID 4561494.
  5. ^ Smith, M. Diane; Green, Ronald R.; Ripley, Lynn S.; Drake, John W. (July 1973). "Thymineless mutagenesis in bacteriophage T4". Genetics. 74 (3): 393–403. doi:10.1093/genetics/74.3.393. PMC 1212957. PMID 4270369.
  6. ^ Deutch, Charles E.; Pauling, Crellin (Sep 1974). "Thymineless mutagenesis in Escherichia coli". J. Bacteriol. 119 (3): 861–7. doi:10.1128/JB.119.3.861-867.1974. PMC 245692. PMID 4605383.
  7. ^ Marlaire, Ruth (2015-03-03). "NASA Ames Reproduces the Building Blocks of Life in Laboratory". www.nasa.gov. NASA. Retrieved 2021-11-15.
  8. ^ Tasker, Elizabeth (2016-11-10). "Did the Seeds of Life Come from Space?". blogs.scientificamerican.com. Scientific American. Retrieved 2016-11-24.
  9. ^ Wheeler, H.I.; Merriam, H.F. (1903). "On some condensation products of the pseudothioureas: synthesis of uracil, thymine, and similar compounds". American Chemical Journal. 29 (5): 478–492.
  10. ^ Guo, Xianghai; Shen, Jiaxiang (2014). "An environmentally benign approach to the synthesis of thymine via hydroformylation of methyl acrylate". Monatshefte für Chemie - Chemical Monthly. 145 (4): 657–661. doi:10.1007/s00706-013-1128-y. S2CID 97367180.

External links edit

  • Thymine MS Spectrum
  • Infoplease Encyclopedia

February 15, 2024
thymine, vitamin, whose, name, sounds, looks, similar, thiamine, confused, with, thymidine, symbol, four, nucleobases, nucleic, acid, that, represented, letters, others, adenine, guanine, cytosine, also, known, methyluracil, pyrimidine, nucleobase, thymine, re. For the B vitamin whose name sounds and looks similar see Thiamine Not to be confused with thymidine Thymine ˈ 8 aɪ m ɪ n symbol T or 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 in 1893 by Albrecht Kossel and Albert Neumann from calf thymus glands hence its name 2 Thymine NamesPreferred IUPAC name 5 Methylpyrimidine 2 4 1H 3H dioneOther names 5 MethyluracilIdentifiersCAS Number 65 71 4 Y3D model JSmol Interactive imageChEBI CHEBI 17821 YChEMBL ChEMBL993 YChemSpider 1103 YECHA InfoCard 100 000 560IUPHAR BPS 4581MeSH ThyminePubChem CID 1135UNII QR26YLT7LT YCompTox Dashboard EPA DTXSID4052342InChI InChI 1S C5H6N2O2 c1 3 2 6 5 9 7 4 3 8 h2H 1H3 H2 6 7 8 9 YKey RWQNBRDOKXIBIV UHFFFAOYSA N YSMILES O C1NC O NC C1CPropertiesChemical formula C 5H 6N 2O 2Molar mass 126 115 g mol 1Density 1 223 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 Solubility in water 3 82 g L 1 Acidity pKa 9 7Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox references Contents 1 Derivation 2 Thymine imbalance causes mutation 3 Theoretical aspects 4 Synthesis 4 1 Laboratory synthesis 5 See also 6 References 7 External linksDerivation editAs 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 up to three phosphoric acid groups producing dTMP deoxythymidine monophosphate dTDP or dTTP for the di and tri phosphates respectively 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 3 Thymine imbalance causes mutation editDuring growth of bacteriophage T4 an imbalance of thymine availability either a deficiency or an excess of thymine causes increased mutation 4 The mutations caused by thymine deficiency appear to occur only at AT base pair sites in DNA and are often AT to GC transition mutations 5 In the bacterium Escherichia coli thymine deficiency was also found to be mutagenic and cause AT to GC transitions 6 Theoretical aspects editIn 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 another carbon rich compound may have been formed in red giants or in interstellar dust and gas clouds according to the scientists 7 Thymine has not been found in meteorites which suggests the first strands of DNA had to look elsewhere to obtain this building block Thymine likely formed within some meteorite parent bodies but may not have persisted within these bodies due to an oxidation reaction with hydrogen peroxide 8 Synthesis editLaboratory synthesis edit Thymine was first prepared by hydrolysis of the corresponding nucleoside obtained from natural sources Interest in its direct chemical synthesis began in the early 1900s Emil Fischer published a method starting from urea but a more practical synthesis used methylisothiourea in a condensation reaction with ethyl formyl propionate followed by hydrolysis of the pyrimidine intermediate 9 nbsp Many other preparative methods have been developed including optimised conditions so that urea can be used directly in the reaction shown above preferably with methyl formyl propionate 10 See also editDeoxyribose Deoxythymidine Nucleobase Pyrimidine Thymineless death UracilReferences edit Dannenfelser R M Yalkowsky S H December 1991 Data base of aqueous solubility for organic non electrolytes Science of the Total Environment 109 110 C 625 628 Bibcode 1991ScTEn 109 625D doi 10 1016 0048 9697 91 90214 Y Retrieved 2021 11 14 Albrecht Kossel Neumann Albert Oct Dec 1893 Ueber das Thymin ein Spaltungsproduct der Nucleinsaure On thymine a cleavage product of nucleic acid Berichte der Deutschen Chemischen Gesellschaft 26 3 2753 2756 doi 10 1002 cber 18930260379 Retrieved 2021 11 14 p 2754 Wir bezeichnen diese Substanz als Thymin We designate this substance as thymine Hofreiter Michael Serre David Poinar Henrik N Kuch Melanie Paabo Svante 2001 05 01 Ancient DNA Nature Reviews Genetics 2 5 353 359 doi 10 1038 35072071 PMID 11331901 S2CID 205016024 Bernstein Carol Bernstein Harris Mufti Siraj Strom Barbara October 1972 Stimulation of mutation in phage T 4 by lesions in gene 32 and by thymidine imbalance Mutat Res 16 2 113 119 doi 10 1016 0027 5107 72 90171 6 PMID 4561494 Smith M Diane Green Ronald R Ripley Lynn S Drake John W July 1973 Thymineless mutagenesis in bacteriophage T4 Genetics 74 3 393 403 doi 10 1093 genetics 74 3 393 PMC 1212957 PMID 4270369 Deutch Charles E Pauling Crellin Sep 1974 Thymineless mutagenesis in Escherichia coli J Bacteriol 119 3 861 7 doi 10 1128 JB 119 3 861 867 1974 PMC 245692 PMID 4605383 Marlaire Ruth 2015 03 03 NASA Ames Reproduces the Building Blocks of Life in Laboratory www nasa gov NASA Retrieved 2021 11 15 Tasker Elizabeth 2016 11 10 Did the Seeds of Life Come from Space blogs scientificamerican com Scientific American Retrieved 2016 11 24 Wheeler H I Merriam H F 1903 On some condensation products of the pseudothioureas synthesis of uracil thymine and similar compounds American Chemical Journal 29 5 478 492 Guo Xianghai Shen Jiaxiang 2014 An environmentally benign approach to the synthesis of thymine via hydroformylation of methyl acrylate Monatshefte fur Chemie Chemical Monthly 145 4 657 661 doi 10 1007 s00706 013 1128 y S2CID 97367180 External links editThymine MS Spectrum Infoplease Encyclopedia Science Aid DNA Structure and Replication Retrieved from https en wikipedia org w index php title Thymine amp oldid 1163337620, wikipedia, wiki, book, books, library,

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