Question

. Why is it thought that almost all NTPs (ribonucleoside triphosphates) in the cell are present as their complexes with Mg (II)?

Answer 1

Magnesium plays several important role in structure and functions of nucleic acids.

1. All ribonucleoside triphosphates are complexes of nucleic acid and phosphate ions. Presence of phosphate ions create abundant negative charge. A single phophate group has two negative charge. In order to counter balance the negative charge, a bivalent, in almost all cases, Magnesium (II) binds with phosphate ions.

2. Moreover, Magnesium (II) is important for RNA folding and structure assembling.

3. Magnesium (II) is critical for functioning of DNA polymerase. It acts as cofactor in DNA excission during DNA repair, and during transcription. Thus, it ensures fidelity of DNA polymerase. Deficiency of Magnesium (II) may cause tumors.

4. Magnesium (II) is a cofactor of the ATP synthase enzyme.  

Thus, it is thought that almost all NTPs in the cell are present as their complexes with Mg (II).