[Spin polymerization of DNA/RNA nucleotides]

Area of Science:

• Computational chemistry
• Biophysical chemistry
• Molecular dynamics

Context:

• Adenine mononucleotides are fundamental building blocks of nucleic acids.
• Magnesium-ATP (adenosine triphosphate) is crucial for numerous biochemical reactions, including DNA replication.
• Ion-radical (IR) polymerization is a proposed mechanism for nucleotide polymerization.

Purpose:

• To investigate the mechanism of ion-radical polymerization of adenine mononucleotides.
• To elucidate the role of Mg2+(H2O)2-ATP(4-) in initiating and controlling IR polymerization.
• To differentiate between triplet (T) and singlet (S/TO) states in the polymerization process.

Summary:

• Car-Parrinello molecular dynamics simulations reveal that IR polymerization of adenine mononucleotides occurs upon excitation of Mg2+(H2O)2-ATP(4-) into a triplet (T) state.
• The polymerization initiates with homolytic hydrogen atom removal from the ribose HO-C3' group and transfer to a hydroxyl radical, forming water.
• The reaction pathway is sensitive to radical recombination and spin states, with the T-state favoring polymerization at HO-C3' and the To state being inert, enabling ionic polymerization at HO-C2'.

Impact:

• Provides a detailed atomistic understanding of a novel polymerization mechanism.
• Highlights the critical role of Mg-ATP complex excitation and spin dynamics in controlling polymerization pathways.
• Offers insights into prebiotic chemistry and the potential origins of RNA/DNA polymerization.