Figure 2.

Integrated data obtained from titration of 20 mM PEI into 1.5 mM DNA (a) in 0.1 M HEPES buffer at pH 7, (b) in 0.1 M MES buffer at pH 7, and (c) in water adjusted to pH 7 by NaOH. The first point in c is out of figure (−1.4 ± 1.0 kJ/mol). The solid line represents the fitting data using the model proposed by Kim et al. (16). The data points are quadruplicate measurements.