FIGURE 8.

Calculation of K_0.5 values of RDD and its variants for Na⁺, Li⁺ and K⁺. For the analysis of the apparent affinity of RDD or its variants for the transported cations, Na⁺/H⁺ (A), Li⁺/H⁺ (B) and K⁺/H⁺ (C) antiport activities of E. coli KNabc transformant cells expressing RDD, R35A, and D42A were plotted as the respective functions of their corresponding cation concentrations. K_0.5 values of RDD and its variants for Na⁺, Li⁺, and K⁺ were obtained, respectively, through the non-linear regression analysis with Prism 5.0. Each value point represents the average of three independent determinations.