Dideoxynucleotides

Dideoxynucleotides, or ddNTPs, are phosphodiester bond can be created based on the fact that deoxyribonucleoside triphosphates (which are the building blocks of DNA) allow DNA chain synthesis to occur through a condensation reaction between the 5' phosphate (following the cleavage of pyrophospate) of the current nucleotide with the 3' hydroxyl group of the previous nucleotide. The dideoxyribonucleosides do not possess a 3' hydroxyl group, hence no further chain elongation can occur once this dideoxynucleotide is on the chain. This can lead to the determination of the DNA sequence. Thus, these molecules form the basis of the dideoxy chain-termination method of DNA sequencing, which was developed by Frederick Sanger in 1977.^[1]