Role of nucleoside components and internucleotide phosphate groups of oligodeoxyribonucleotide template in its binding to human DNA polymerase α

Affinity labelling of human placenta DNA polymerase α (EC 2.7.7.7) with the reactive oligodeoxyribonucleotide d(pT) 2pC[Pt 2+(NH 3) 2OH](pT) 7 was used for quantitative analysis of enzyme interaction with oligodeoxyribonucleotides as templates. Dissociation constants and Gibb's energy values for different oligothymidylates d(pT) n T where n = 1–14 have been evaluated by competitive experiments of these ligands with Pt 2+ reagent. The data obtained prove the formation of one Me 2+-dependent electrostatic contact and a hydrogen bond between the enzyme and one phosphate of these templates. One may suppose that the hydrophobic interaction of any other monomeric link of oligodeoxyribonucleotides with the enzyme template site takes place.