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As the name suggests, it consists of thymine which is bound to the deoxyribose sugar. Nucleoside consist of a five-carbon sugar which can be deoxyribose or ribose. Thymidine is a pyrimidine nucleoside, which is a glycoside made by disintegration of nucleic acids.
Thymine and thymidine are the nucleobase pyrimidine, where thymidine is a nucleoside comprising of sugar and thymine and to the nucleoside when a phosphate group is attached it is called as nucleotide. For instance, thymidine triphosphate is a nucleotide as it possess phosphate group, and the function of TTP is that it is involved in formation of DNA.
What is Thymidine?
In appearance it looks like white colored, crystal powdered. Its weight is 242.229g/mol. As thymidine consist of deoxyribose sugar, hence it is also known as deoxythymidine.
It a part of DNA and is present in all living entities. Its chemically written as C10H14N2O5. Thymine precursors do not engage in RNA synthesis, only engaged in DNA synthesis. In DNA synthesis, thymine is complementary to deoxyadenosine.
From De-novo synthesis pathway, taking place in the liver, nucleosides can be formed. However, through food as well they can be added in our body where they are broken by nucleotidases to form nucleosides and phosphates. By nucleosidases, which are in the lumen of GI tract, nucleosides are broken. Thymidine can be obtained from foods comprising DNA like pulses, legumes, fish and others.
Thymidine nucleoside can be transformed to nucleotide by getting phosphorylated by kinases. Without the phosphate group, nucleotide is a nucleoside. On getting phosphorylated once, thymidine will result in deoxythymidine monophosphate and when phosphorylated with two phosphate groups it is called as deoxythymidine diphosphate and similarly when three deoxythymidine triphosphate which bounds with deoxyadenosine triphosphate and is the building block for synthesis of DNA and is also found in tRNA.
Medical Importance of Thymidine
It has various medical importance like it used to cure herpes simplex keratitis, where it’s used in the form of cream as Iododeoxyuridine, a derivative of thymidine. Another importance is in curing HIV, where it restricts the reverse transcription process of HIV cycle and the drug used is Azidothymidine for treating the patients.
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