deoxynucleotides

Deoxynucleotides are nucleotides that contain a deoxyribose sugar and the four standard bases—adenine, cytosine, guanine, and thymine. In biology, the term most often refers to the deoxyribonucleotide triphosphates (dNTPs): dATP, dCTP, dGTP, and dTTP. They also exist as deoxynucleoside monophosphates (dNMPs) and other phosphate forms, depending on metabolic state; however, the triphosphate forms are the substrates used by DNA polymerases to elongate DNA strands.

Each dNTP consists of a deoxyribose sugar linked to a base and a triphosphate group. During DNA synthesis, DNA polymerases add a dNTP to the 3' end of a growing strand, releasing pyrophosphate. The synthesis proceeds in the 5' to 3' direction with base-pairing rules—A pairs with T, and G pairs with C. The absence of the 2' hydroxyl on the sugar (2'-deoxyribose) distinguishes DNA nucleotides from RNA nucleotides.

In cells, the pools of dNTPs are tightly regulated by ribonucleotide reductase and various salvage and de novo pathways. Balanced dNTP levels are essential for replication fidelity; imbalances can increase mutation rates or cause DNA damage and cytotoxicity.

Deoxynucleotides have broad relevance in biotechnology and medicine. They are used in PCR and DNA sequencing, and numerous analogs act as antiviral or anticancer agents by terminating DNA synthesis or inhibiting replication. The metabolism and regulation of deoxynucleotides remain important targets in research and therapy.