Charge transfer and transport in DNA

Area of Science:

• Biophysics
• Molecular Biology
• Physical Chemistry

Background:

• Understanding charge migration in DNA is crucial for applications like molecular electronics and understanding DNA damage.
• Two primary mechanisms, superexchange and multistep charge transport, have been proposed for charge separation in DNA.
• The DNA base sequence and energetics are known to influence charge migration dynamics.

Purpose of the Study:

• To elucidate the distinct mechanisms of charge separation in DNA donor-bridge-acceptor systems.
• To investigate the roles of superexchange and multistep charge transport in DNA.
• To determine how DNA base sequence and energetics control charge migration pathways.

Main Methods:

• Theoretical modeling of charge separation in donor-bridge-acceptor DNA systems.
• Analysis of superexchange (unistep) and multistep charge transport mechanisms.
• Investigation of the dependence of charge separation rate, yield, and lifetime on distance and DNA sequence.

Main Results:

• Off-resonance coupling favors unistep superexchange, with charge separation rate and yield exponentially dependent on distance.
• Resonance coupling favors multistep charge transport, exhibiting weaker algebraic dependence on distance and base number.
• DNA base sequence and energetics of ion pair states relative to excited donor states dictate the dominant charge migration mechanism.

Conclusions:

• Charge migration in DNA is controlled by the interplay between electronic coupling and DNA sequence-specific energetics.
• The findings establish conditions for 'chemistry at a distance' via controlled charge transport in DNA.
• Sequence-controlled charge migration mechanisms are applicable to various molecular systems, including proteins and DNA.