Thymine

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Thymine

IUPAC name	5-Methylpyrimidine-2,4(1H,3H)-dione
Identifiers
CAS number	[65-71-4]
MeSH	Thymine
SMILES	CC1=CNC(NC1=O)=O
Properties
Molecular formula	C₅H₆N₂O₂
Molar mass	126.11334 g/mol
Melting point	316 - 317 °C
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

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For the similarly-spelled vitamin compound, see Thiamine

Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. As the name implies, thymine may be derived by methylation of uracil at the 5th carbon. Thymine is found in the nucleic acid DNA. In RNA thymine is replaced with uracil in most cases. In DNA, thymine(T) binds to adenine (A) via two hydrogen bonds to assist in 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-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 inhibit DNA synthesis in actively dividing cells.

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v • d • e Major Families of Biochemicals
Peptides \| Amino acids \| Nucleic acids \| Carbohydrates \| Lipids \| Terpenes \| Carotenoids \| Tetrapyrroles \| Enzyme cofactors \| Steroids \| Flavonoids \| Alkaloids \| Polyketides \| Glycosides
Analogues of nucleic acids:	Types of Nucleic Acids	Analogues of nucleic acids:
Nucleobases:	Adenine \| Thymine \| Uracil \| Guanine \| Cytosine \| Purine \| Pyrimidine
Nucleosides:	Adenosine \| Uridine \| Guanosine \| Cytidine \| Deoxyadenosine \| Thymidine \| Deoxyguanosine \| Deoxycytidine
Nucleotides:	AMP \| UMP \| GMP \| CMP \| ADP \| UDP \| GDP \| CDP \| ATP \| UTP \| GTP \| CTP \| cAMP \| cADPR \| cGMP
Deoxynucleotides:	dAMP \| TMP \| dGMP \| dCMP \| dADP \| TDP \| dGDP \| dCDP \| dATP \| TTP \| dGTP \| dCTP
Ribonucleic acids:	RNA \| mRNA \| piRNA \| tRNA \| rRNA \| ncRNA \| sgRNA \| shRNA \| siRNA \| snRNA \| miRNA \| snoRNA \| LNA
Deoxyribonucleic acids:	DNA \| mtDNA \| cDNA \| plasmid \| Cosmid \| BAC \| YAC \| HAC
Analogues of nucleic acids:	GNA \| PNA \| TNA \| morpholino