Nucleoside diphosphates (NDPs) are pivotal molecules in a plethora of cellular processes. The exothermic hydrolysis of ATP yielding ADP and inorganic phosphate (Pi) is the major source of biological energy, and ATP/ADP as well as GTP/GDP are involved in the signal transduction pathways by kinases and G-Proteins.
NDPs can be converted to their triphosphates (NTP) by kinase-mediated enzymatic attachment of one additional phosphate while NTPs in combination with a phosphatase are converted back to NDPs (Fig. 1).
NDPs are widely used in signal transduction research as cofactors and serve as templates for chemical or enzymatic synthesis of non-natural analogues.
Figure 1: Dynamic equilibrium of nucleoside diphosphate (NDP) and its triphosphate (NTP)