dADP

dADP, short for deoxyadenosine diphosphate, is a deoxyribonucleotide comprising a deoxyribose sugar, the adenine base, and two phosphate groups. As a member of the deoxyribonucleotide diphosphates, it participates in the metabolism and synthesis of DNA alongside other dNTPs such as dCTP, dGTP, and dTTP.

In cellular metabolism, dADP helps maintain balanced pools of deoxyribonucleotides required for DNA replication and repair. Its levels are regulated by kinases and phosphatases that interconvert dNTPs. The primary regulatory enzymes are nucleoside diphosphate kinases (NDPKs), which catalyze phosphate transfer between nucleoside triphosphates and diphosphates. A typical reaction is dADP + ATP ⇄ dATP + ADP, which helps supply dATP for DNA synthesis and maintains nucleotide balance.

dADP can be formed from dATP dephosphorylation or from the interconversion of dNTPs, depending on the cellular needs. It is a transient intermediate rather than a stored metabolite, with its main significance lying in contributing to the dNTP pool used by DNA polymerases during replication and repair.

In research and clinical contexts, dADP levels are measured to assess nucleotide balance and cellular metabolism, often alongside other dNTPs through analytic techniques such as high-performance liquid chromatography or mass spectrometry.