dNTPs

Deoxynucleotide triphosphates, abbreviated dNTPs, are the building blocks of DNA. The four canonical nucleotides are dATP, dTTP, dCTP, and dGTP. Each molecule consists of a deoxyribose sugar, a nitrogenous base (adenine, thymine, cytosine, or guanine), and a chain of three phosphate groups attached at the 5' position. The triphosphate moiety provides the energy for polymerization.

During DNA replication and repair, DNA polymerases select the complementary dNTPs and catalyze the formation of a phosphodiester bond between the 3' hydroxyl of the growing strand and the alpha-phosphate of the incoming dNTP. Release of pyrophosphate (the beta and gamma phosphates) drives the reaction forward after hydrolysis. Fidelity depends on proper base pairing and the selectivity of the polymerase for the correct dNTP.

Cells maintain pools of balanced dNTPs through de novo synthesis and salvage pathways. Ribonucleotide reductase converts NDPs to dNDPs, which are further phosphorylated to dNTPs; regulatory mechanisms couple dNTP levels to overall nucleotide metabolism. Imbalances in dNTP pools can increase mutation rates and cause replication stress.

In molecular biology, dNTPs are supplied as ready-to-use mixtures for PCR, sequencing, and other DNA assays. They are typically stored refrigerated or frozen and used in equimolar mixes to ensure balanced incorporation. In vivo, depletion or imbalance of dNTP pools can influence replication and is a target of certain therapeutic strategies.