1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Folding transition of a single semiflexible polyelectrolyte chain through toroidal bundling of loop structures
Rent:
Rent this article for
USD
10.1063/1.2967860
/content/aip/journal/jcp/129/6/10.1063/1.2967860
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/6/10.1063/1.2967860
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Schematic representation of a rings-on-a-string chain. A ring structure (an aggregate of loops) is characterized by the winding number and the mean loop length . By regarding the ring as a torus, we can introduce other shape parameters, i.e., torus radius and torus thickness , as in the figure. The inset electron micrograph of the T4 DNA (total length ) segregated structure is reprinted with permission from Ref. 16.

Image of FIG. 2.
FIG. 2.

Theoretical characterization of the folding transition of DNA. The figures correspond to solutions with ionic strengths of (a) , (b) , and (c) , respectively. The top row shows the equilibrium fractions of an unfolded part in a folded chain vs , the variation of the normal surface energy of the chain segments in the solution. corresponds to an equiprobable point between unfolded and folded chains. The second row shows the relative probability densities of the folded chain at as functions of the fraction of unfolded segments. The bottom row shows estimated histograms of long-axis lengths of T4 DNA chains at the equiprobable point, where a black bar represents the folded chain, and a light gray bar represents the unfolded chain.

Image of FIG. 3.
FIG. 3.

Experimental results regarding the folding transition of T4 DNA by spermidine through single-DNA observation with highly sensitive fluorescence microscopy. The figures correspond to (a) , (b) , and (c) NaCl solutions, respectively. The top row shows observed fractions of coils (○), globules (●), and partially folded chains (×) vs the concentration of spermidine [SPD]. The bottom row shows histograms of the long-axis lengths (maximum breadth of a fluorescent region on a focal plane) for coils (light gray bars) and folded chains (black bars). We inset these histograms with the pseudo-three-dimensional expression of the fluorescent intensity for typical fluorescent images of DNA. Each histogram corresponds to the condition proximate to the equiprobable point between coils and folded chains. The fractions of coils are (a) 23%, (b) 34%, and (c) 63%, respectively.

Image of FIG. 4.
FIG. 4.

Experimental results regarding the folding transition of T4 DNA at high-salt concentration, showing the seemingly continuous nature of the transition. The left histograms show the distributions of the long-axis lengths of coils (light gray bars), partially folded chains (gray bars) and globules (black bars) of T4 DNA The solution contains NaCl and spermidine, with the concentration indicated in the figure. Figures on the right are typical fluorescent images of DNA, the pseudo-three-dimensional expression of their fluorescent intensity, and the corresponding schematic representations of DNA conformation, representing the classes indicated by , , , , and in the histograms on the left, respectively.

Image of FIG. 5.
FIG. 5.

Theoretical expectation regarding the dependence of (a) the equilibrium fraction of unfolded segments , (b) the equilibrium ring size , and (c) the equilibrium winding number of a ring on the salt concentration. The normal surface energy is set to induce equiprobability between unfolded and folded chains.

Image of FIG. 6.
FIG. 6.

Theoretical prediction regarding the dependence of the folded chain conformation on elasticity (persistence length ). The entire solution stays at the equiprobable point between unfolded and folded chains. The concentration of salt is . The figures show (a) the distribution and free energy profile of a folded chain, (b) the average size of a ring , and (c) the average winding number of a ring vs the fraction of string segments . The lines correspond to (solid lines), (dot-dashed lines), and (dashed lines).

Image of FIG. 7.
FIG. 7.

Theoretical prediction regarding the dependence of the folded chain conformation on the packing density . The entire solution stays at the equiprobable point of unfolded and folded chains. The concentration of salt is . The figures show (a) the distribution and free energy profile of a folded chain, (b) the average size of a ring , and (c) the average winding number of a ring vs the fraction of string segments . The lines correspond to (solid lines), (dot-dashed lines), and (dashed lines).

Image of FIG. 8.
FIG. 8.

Experimental result regarding the histograms of the long-axis lengths and the hydrodynamic radii of DNA globules in the presence of (a) NaCl and spermidine and (b) NaCl and spermidine. The panels on the bottom show typical fluorescent images of the globules and the trajectories of their center positions over (61 frames). From such a time trace, the hydrodynamic radius is obtained based on the Einstein-Stokes relationship.

Loading

Article metrics loading...

/content/aip/journal/jcp/129/6/10.1063/1.2967860
2008-08-14
2014-04-20
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Folding transition of a single semiflexible polyelectrolyte chain through toroidal bundling of loop structures
http://aip.metastore.ingenta.com/content/aip/journal/jcp/129/6/10.1063/1.2967860
10.1063/1.2967860
SEARCH_EXPAND_ITEM