Ribonucleoside diphosphate (NDP) is one of the ribose-containing nucleosides with one or more phosphate groups linked to the 5´ carbon of the pentose sugar. When a nucleoside contains the sugar deoxyribose, the nucleotides are called deoxyribonucleoside mono-, di-, or tri-phosphates (dNMP, dNDP, or dNTP).