Effects of salt solutions on DNA Micromechanics under tension

Abstract

The main objective of this research is to experimentally and numerically investigate the effects of salt conditions on the mechanical properties of single DNA molecules under tension. In particular, the ionic effects of sodium and magnesium salt solutions on the first and second overstretching transitions are examined. The elastic properties of DNA are studied by curve fitting of the experimental data with the extensible worm-like chain model, Odijk-Skolnick-Fixman theory and elastic moduli renormalization model. A three-dimensional model, namely the modified ZZO model, is proposed to investigate the ionic effects on the first overstretching transition of DNA. The ionic effects on the second overstretching transition of DNA are experimentally studied using optical tweezers and numerically investigated by the three-state Ising-like model and kinetic model.