Thermodynamic parameters of AraR-DNA interaction reactions.

aDissociation constant (Kd) of binding of AraR and AraR mutants (Y5F, E30A) to a wild-type araABDLMNPQ-abfA promoter (WT) and mutants (ORA1 T6→G, T16→G, A1→C, G5→T) calculated by densitometric quantification of the bands corresponding to free DNA and protein–DNA complex by EMSA (see Materials and Methods). The values represent the average and standard deviation of at least three (three to seven) independent assays, with an intrinsic error bp-value (Mann Whitney U test) for each pairwise comparison, mutant DNA fragment vs wild-type DNA fragment. Mutated operators that did not show statistical significant variation (pcGibbs free energy is calculated from the equilibrium association constant Kass (see Materials and Methods).dVariation of Gibbs free energy = [ΔG°mutant−ΔG°wild-type]. ND – not determined.Thermodynamic parameters of AraR-DNA interaction reactions.