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Scaling exponents and probability distributions of DNA end-to-end distance | | Francesco Valle
; Melanie Favre
; Paolo De Los Rios
; Angelo Rosa
; Giovanni Dietler
; | | Date: |
23 Mar 2005 | | Subject: | Soft Condensed Matter; Statistical Mechanics | cond-mat.soft cond-mat.stat-mech | | Abstract: | Correlation length exponent $
u$ for long linear DNA molecules was determined by direct measurement of the average end-to-end distance as a function of the contour length $s$ by means of atomic force microscopy (AFM). Linear DNA, up to 48’502 base pairs (bp), was irreversibly deposited from a solution onto silanized mica and imaged in air. Under the adsorption conditions used, the DNA is trapped onto the surface without any two-dimensional equilibration. The measured exponent is $
u = 0.589 pm 0.006$, in agreement with the theoretical 3D value of $
u = 0.5880 pm 0.0010$. The persistence length $ell_p$ of DNA was estimated to be 44$pm$3 nm, in agreement with the literature values. The distribution of the end-to-end distances for a given contour length $s$ and the exponents characterizing the distribution were determined for different $s$. For $s$ smaller or comparable to $ell_p$, a delta function like distribution was observed, while for larger $s$, a probability distribution of the type $x^{d-1}x^g e^{-bx^delta}$ was observed with $g=0.33pm0.22$ and $delta=2.58pm0.76$. These values are compared to the theoretical exponents for Self-Avoiding Walk (SAW): namely $g=frac{gamma-1}{
u}$ and $delta=(1-
u)^{-1}$. So for $d=2$, $gapprox0.44$ and $delta=4$, while for $d=3$, $gapprox0.33$ and $deltaapprox2.5$. The derived entropic exponent $gamma$ is $gamma=1.194pm0.129$. The present data indicate that the DNA behaves on large length scales like a 3 dimensional SAW. | | Source: | arXiv, cond-mat/0503577 | | Other source: | [GID 371408] pmid16241768 | | Services: | Forum | Review | PDF | Favorites | |
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