Question

To incorporate radiolabeled nucleotides into newly synthesized DNA, researchers use α-phosphorus32-labeled nucleotides, in a DNA synthesis reaction, where the α denotes the position of the radioactive phosphate moiety. Explain why the α position--rather than the β or γ positions--is the best position for the radioactive group in these experiments.

Answer 1

DNA polymerase acts on a 3'OH for nucleophilic attack on the one of the phosphate attached to the 5' carbon on another nucleotide subunit.

3'OH shows nucleophilic attack on triphosphate group which is on the 5' carbon that makes us understand why researchers use α-phosphorus32-labeled nucleotides.

Phosphate bonds are high energy therefore when the 3'OH has its nucleophilic attack then it will not attack phosphates in the β or γ positions as they are not energetically favorable.

It will attack the phosphate in the α position which is is closest to the 5' carbon.

When DNA is synthesized then β and γ phosphates cleaved and α phosphate bonds form polymer with the 3'OH.

So we conclude, α position is the only phosphate that is incorporated into the newly synthesized DNA molecule....