Dideoxynucleotide

Didesoxyribonukleosid triphosphates ( ddNTP ) are artificial DNA nucleotides which are used in DNA sequencing according to Sanger using. The ddNTPs are the deoxyribonucleoside triphosphates (dNTPs ) constructed like. However, the ribose (sugar) is deoxidized at position 2 'and 3'. Characterized missing at the 3 -carbon atom, the hydroxy group, in the polymerization of the next nucleotide is added.

Expanding the DNA polymerase during replication at a location such a ddNTP, there can be no further nucleotide are attached, and the polymerization stops at this point. It can therefore be simplified by stop - nucleotides speak.

In DNA sequencing according to Sanger, the four natural dNTPs and one of the four ddNTPs artificial now be added to a PCR reaction with the DNA to be sequenced and a corresponding primer. The polymerase is now building up occasionally in a random distribution, a ddNTP one, whereby polymerization terminates. It will therefore have a mixture of different lengths of pieces to be sequenced portion of the DNA. This experiment is carried by all four ddNTPs and carries the four batches in a polyacrylamide gel electrophoresis side by side on. From the pattern of the resulting bands can then be read off the sequence of bases on the DNA section.