deoxythymidine

Deoxythymidine, also called 2′-deoxythymidine or thymidine in the context of DNA chemistry, is the deoxyribonucleoside formed by the attachment of thymine to deoxyribose via a β-N-glycosidic bond. It is one of the four canonical deoxyribonucleosides that constitute DNA and pairs with adenine through two hydrogen bonds.

In its free nucleoside form, deoxythymidine serves as a substrate and metabolic intermediate in nucleotide metabolism. It can be phosphorylated by thymidine kinase to form deoxythymidine monophosphate (dTMP), which may be further phosphorylated to deoxythymidine triphosphate (dTTP) and incorporated into DNA during replication and repair. Deoxythymidine can also be degraded by thymidine phosphorylase to thymine and 2-deoxyribose-1-phosphate, connecting pyrimidine turnover to carbohydrate metabolism.

Biosynthesis and turnover: In cells, thymidine is supplied by DNA turnover and by salvage pathways that recycle thymidine into the nucleotide pool. The balance between phosphorylation by thymidine kinase and degradation by thymidine phosphorylase helps regulate dTTP levels, which are critical for faithful DNA synthesis and genome stability.

Applications and relevance: In laboratory and clinical research, deoxythymidine and its phosphorylated derivatives are used to study nucleotide metabolism, salvage pathways, and the regulation of dNTP pools. Alterations in thymidine metabolism can influence DNA replication fidelity and sensitivity to certain chemotherapeutic agents.

See also: thymidine, deoxyribonucleoside, dNTP, thymidine kinase, thymidine phosphorylase.