Structural stability versus conformational sampling in biomolecular systems: Why is the charge transfer efficiency in G4-DNA better than in double-stranded DNA?

TL;DR

This study combines electronic structure calculations, molecular dynamics, and tight-binding models to explain why G4-DNA exhibits better charge transfer efficiency than double-stranded DNA, emphasizing conformational flexibility over stability.

Contribution

It reveals that G4-DNA's superior charge transfer is due to its ability to access more charge-transfer active conformations, not just its structural stability.

Findings

G4-DNA explores more charge-transfer active conformations.

Interstrand matrix elements enable additional charge pathways.

G4-DNA maintains conduction properties better when contacted by electrodes.

Abstract

The electrical conduction properties of G4-DNA are investigated using a hybrid approach, which combines electronic structure calculations, molecular dynamics (MD) simulations, and the formulation of an effective tight-binding model Hamiltonian. Charge transport is studied by computing transmission functions along the MD trajectories. Though G4-DNA is structurally more stable than double-stranded DNA (dsDNA), our results strongly suggest that the potential improvement of the electrical transport properties in the former is not necessarily related to an increased stability, but rather to the fact that G4 is able to explore in its conformational space a larger number of charge-transfer active conformations. This in turn is a result of the non-negligible interstrand matrix elements, which allow for additional charge transport pathways. The higher structural stability of G4 can however play an important role once the molecules are contacted by electrodes. In this case, G4 may experience weaker structural distortions than dsDNA and thus preserve to a higher degree its conduction properties.