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CD Spectroscopy to Study DNA-Protein Interactions

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Published on: February 10, 2022

Electronic excitations and spectra in single-stranded DNA.

Stefano Tonzani¹, George C Schatz

¹Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, USA. tonzani@northwestern.edu

Journal of the American Chemical Society

|May 22, 2008

Summary

Delocalized electronic states spanning three bases were directly excited in single-stranded DNA. This finding aligns with experimental data on DNA delocalization length, even with strong base stacking.

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Area of Science:

Computational chemistry
Biophysics
Molecular dynamics

Background:

Understanding electronic properties of DNA is crucial for fields like molecular electronics and sensing.
Previous studies have explored charge transport and delocalization in DNA, but direct excitation of delocalized states in single-stranded DNA remains an area of active research.

Purpose of the Study:

To investigate the direct excitation of delocalized electronic states in single-stranded poly(A) DNA using computational methods.
To compare simulation results with experimental data on delocalization length and circular dichroic spectra.

Main Methods:

Density functional theory (DFT) calculations.
Molecular dynamics (MD) simulations.
Validation of structural models using calculated circular dichroic (CD) spectra.

Main Results:

Direct excitation of delocalized states extending over three bases was observed in single-stranded poly(A) DNA.
Simulation results for delocalization length showed semiquantitative agreement with experimental findings for both single- and double-stranded DNA.
Calculated CD spectra for short DNA oligomers (d(A)2 and d(A)4) matched experimental data, confirming the validity of the simulated structures.

Conclusions:

The study confirms the existence and direct excitation of three-base delocalized states in single-stranded DNA.
The findings suggest that significant base stacking in single-stranded DNA does not preclude short-range delocalization.
Computational methods employed provide a reliable approach for studying electronic properties and structural dynamics of DNA.