– 2′-Deoxyadenosine-5′-triphosphate (dATP) is a purine nucleotide and derivative of the nucleic acid adenosine 5′-triphosphate .1dATP is a substrate for DNA polymerase in the synthesis of DNA.2It is a noncompetitive inhibitor of ribonucleotide reductases, which provides feedback inhibition during DNA synthesis.1dATP has commonly been used in DNA synthesis, sequencing, and labeling in research applications.3,4dATP accumulates in adenosine deaminase deficiency, a disorder characterized by mutations in the gene for adenosine deaminase, the enzyme that catalyzes the deamination of adenosine and deoxyadenosine.5