The pulling force of a single DNA molecule condensed by spermidine

Physica A: Statistical Mechanics and its Applications

Volumn 349, Issue 3-4, 2005, Pages 563-570

  Zhang, Rui ^a   Shklovskii, B I ^a  

^a UNIVERSITY OF MINNESOTA   (United States)

Author keywords

Condensation; DNA; Pulling force; Spermidine

Indexed keywords

CELL MEMBRANES; CONDENSATION; FREE ENERGY; FUNCTIONS; LOADS (FORCES); POLYELECTROLYTES; POLYSTYRENES; POSITIVE IONS; PROTEINS;

HISTONES; PULLING FORCE; REENTRANT CONDENSATION; SPERMIDINE;

DNA;

EID: 13444283512     PISSN: 03784371     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.physa.2004.11.013     Document Type: Article

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11. This calculation overestimates the screening effect because of the significant length of the spermidine molecule. We can get a pretty good estimate of r s from above considering each spermidine molecule as three separate positive monovalent i ons, which gives r s = 17 Å. Our final result is not sensitive to this variation of r s: the corresponding variation of |ε| is less than 7%.
12. H. Wada, Y. Murayama, and M. Sano Phys. Rev. E 66 2002 061912
13. Strictly speaking, at x → x 0, our theory is not valid because the toroidal condensate becomes so small that f 0 starts to decrease (the surface energy of the toroid cannot be ignored in this limit). Therefore at x close to x 0, the pulling force f first decreases a little bit with increasing x, and then goes back to the wormlike chain behavior.