Effects of magnesium salt concentrations on B-DNA overstretching transition |
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Authors: | H Fu H Chen C G Koh and C T Lim |
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Institution: | (1) Department of Physics, National University of Singapore, 117542 Singapore, Singapore;(2) Department of Civil Engineering, National University of Singapore, 117542 Singapore, Singapore;(3) Division of Bioengineering and Department of Mechanical Engineering, National University of Singapore, 117542 Singapore, Singapore |
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Abstract: | In this study, we use optical tweezers to investigate the ionic effects of magnesium salt solutions on the overstretching
transition of single B-DNA molecules. The experimental data are compared with those in sodium salt solutions. The overstretching
transition force increases when the NaCl or MgCl2 salt concentration increases. Magnesium cations have much stronger effects on the overstretching transition force than sodium
cations. For both NaCl and MgCl2 salt solutions, the overstretching transition force is linear with the natural logarithm of salt concentration, which confirms
the theory proposed in previous paper. The modified ZZO model is applied to study the electrostatic contribution of magnesium
salt solutions to the overstretching transition of single B-DNA molecules. The consistency between the experimental data and
analytical results shows that the modified ZZO model can simulate the transition behavior of single B-DNA molecules in different
NaCl and MgCl2 salt solutions. |
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Keywords: | PACS" target="_blank">PACS 61 25 HM acromolecular polymers solutions polymer melts 87 15 Zg Phase transitions 87 15 La Mechanical properties |
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