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Thymine (/ ˈ θ aɪ m ɪ n /) (symbol T or Thy) is one of the four nucleotide bases 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.
In its composition, deoxythymidine is a nucleoside composed of deoxyribose (a pentose sugar) joined to the pyrimidine base thymine.. Deoxythymidine can be phosphorylated with one, two or three phosphoric acid groups, creating dTMP (deoxythymidine monophosphate), dTDP, or dTTP (for the di- and tri- phosphates, respectively).
Each unit is joined when a covalent bond forms between its phosphate group and the pentose sugar of the next nucleotide, forming a sugar-phosphate backbone. DNA is a complementary, double stranded structure as specific base pairing (adenine and thymine, guanine and cytosine) occurs naturally when hydrogen bonds form between the nucleotide bases.
It has an S-shape with a length of 110 Å and a width of 60 Å. Each monomer is composed of 440 amino acids and is composed of a small α-helical domain and a large α/β domain. The surface of the enzyme is smooth except for a 10 Å deep and 8 Å wide cavity between the two domains that contains the thymine, thymidine, and phosphate binding ...
The deoxyribose sugar joined only to the nitrogenous base forms a Deoxyribonucleoside called deoxyadenosine, whereas the whole structure along with the phosphate group is a nucleotide, a constituent of DNA with the name deoxyadenosine monophosphate. Nucleotides are organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate.
Other DNA and RNA nucleotide bases that are linked to the ribose sugar via a glycosidic bond are thymine, cytosine and uracil (which is only found in RNA). Uridine monophosphate biosynthesis involves an enzyme that is located in the mitochondrial inner membrane and multifunctional enzymes that are located in the cytosol .
The protein encoded by this gene belongs to the TDG/mug DNA glycosylase family. Thymine-DNA glycosylase (TDG) removes thymine moieties from G/T mismatches by hydrolyzing the carbon-nitrogen bond between the sugar-phosphate backbone of DNA and the mispaired thymine. With lower activity, this enzyme also removes thymine from C/T and T/T mispairings.
However, there is one crucial difference in the nucleotide composition of DNA and mRNA molecules. DNA is composed of the bases: guanine, cytosine, adenine and thymine (G, C, A and T). RNA is also composed of four bases: guanine, cytosine, adenine and uracil. In RNA molecules, the DNA base thymine is replaced by uracil which is able to base pair ...