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Title: The Role of Cytosine Methylation on Charge Transport through a DNA Strand

Cytosine methylation has been found to play a crucial role in various biological processes, including a number of human diseases. The detection of this small modifi-cation remains challenging. In this work, we computationally explore the possibility of detecting methylated DNA strands through direct electrical conductance measurements. Using density functional theory and the Landauer-Buttiker method, we study the electronic properties and charge transport through an eight base-pair methylated DNA strand and its native counterpart. Specifically, we compare the results generated with the widely used B3LYP exchange-correlation (XC) functional and CAM-B3LYP based tuned range-separated hybrid density functional. We first analyze the effect of cytosine methylation on the tight-binding parameters of two DNA strands and then model the transmission of the electrons and conductance through the strands both with and without decoherence. We find that with both functionals, the main difference of the tight-binding parameters between the native DNA and the methylated DNA lies in the on-site energies of (methylated) cytosine bases. The intra- and interstrand hopping integrals between two nearest neighboring guanine base and (methylated) cytosine base also change with the addition of the methyl groups. Our calculations show that in the phase-coherent limit, the transmission of the methylated strand is closemore » to the native strand when the energy is nearby the highest occupied molecular orbital (HOMO) level and larger than the native strand by 5 times in the bandgap. The trend in transmission also holds in the presence of the decoherence with both functionals. We also study the effect of contact coupling by choosing coupling strengths ranging from weak to strong coupling limit. Our results suggest that the effect of the two different functionals is to alter the on-site energies of the DNA bases at the HOMO level, while the transport properties don't depend much on the two functionals.« less
Authors:
 [1] ;  [2] ;  [1]
  1. Univ. of Washington, Seattle, WA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
OSTI Identifier:
1229984
Report Number(s):
PNNL-SA-106687
Journal ID: ISSN 0021-9606; 48614; KC0301060
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 9
Publisher:
American Institute of Physics (AIP)
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
Charge transport; Cytosine methylation; Density functional theory; Green's function; Environmental Molecular Sciences Laboratory