| Description | Thymine, also known as 5-methyluracil, belongs to the class of organic compounds known as hydroxypyrimidines. These are organic compounds containing a hydroxyl group attached to a pyrimidine ring. Pyrimidine is a 6-membered ring consisting of four carbon atoms and two nitrogen centers at the 1- and 3- ring positions. Thymine was first isolated in 1893 by Albrecht Kossel and Albert Neumann from calves' thymus glands, hence its name. Thymine is one of the 4 nuelcoebases found in DNA and is essential to all life. Thymine exists in all living species, ranging from bacteria to plants to humans. Thymine combined with deoxyribose creates the nucleoside deoxythymidine (also called thymidine) which when phosphorylated to dTDP can be incorporated into DNA via DNA polymerases. Thymidine can be phosphorylated with up to three phosphoric acid groups, producing dTMP (deoxythymidine monophosphate) dTDP and/or dTTP. In RNA thymine is replaced with uracil in most cases. In DNA, thymine binds to adenine via two hydrogen bonds to assist in stabilizing the nucleic acid structures. Within humans, thymine participates in a number of enzymatic reactions. In particular, thymine and deoxyribose 1-phosphate can be biosynthesized from thymidine through its interaction with the enzyme thymidine phosphorylase. In addition, thymine can be converted into dihydrothymine; which is mediated by the enzyme dihydropyrimidine dehydrogenase [NADP(+)]. |
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