期刊
JOURNAL OF CHEMICAL PHYSICS
卷 136, 期 9, 页码 -出版社
AIP Publishing
DOI: 10.1063/1.3682984
关键词
DNA; molecular biophysics; molecular configurations; Monte Carlo methods
资金
- Korea Research Foundation (KRF)
- Korea government (MEST) [2010-0003087, 2011-0027428]
- Kwangwoon Research Fund
- National Research Foundation of Korea [2010-0003087, 2009-0088221] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
We have performed canonical ensemble Monte Carlo simulations of a primitive DNA model to study the conformation of 2.56 similar to 21.8 mu m long DNA molecules confined in nanochannels at various ionic concentrations with the comparison of our previous experimental findings. In the model, the DNA molecule is represented as a chain of charged hard spheres connected by fixed bond length and the nanochannels as planar hard walls. System potentials consist of explicit electrostatic potential along with short-ranged hard-sphere and angle potentials. Our primitive model system provides valuable insight into the DNA conformation, which cannot be easily obtained from experiments or theories. First, the visualization and statistical analysis of DNA molecules in various channel dimensions and ionic strengths verified the formation of locally coiled structures such as backfolding or hairpin and their significance even in highly stretched states. Although the folding events mostly occur within the region of similar to 0.5 mu m from both chain ends, significant portion of the events still take place in the middle region. Second, our study also showed that two controlling factors such as channel dimension and ionic strength widely used in stretching DNA molecules have different influence on the local DNA structure. Ionic strength changes local correlation between neighboring monomers by controlling the strength of electrostatic interaction ( and thus the persistence length of DNA), which leads to more coiled local conformation. On the other hand, channel dimension controls the overall stretch by applying the geometric constraint to the non-local DNA conformation instead of directly affecting local correlation. Third, the molecular weight dependence of DNA stretch was observed especially in low stretch regime, which is mainly due to the fact that low stretch modes observed in short DNA molecules are not readily accessible to much longer DNA molecules, resulting in the increase in the stretch of longer DNA molecules. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3682984]
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