Figure 3. Determination of the LdPEX14–LdPEX5 equilibrium dissociation constant.

Microtitre plates were coated with His₆/S–LdPEX14 and then incubated with increasing amounts of LdPEX5 (■), ldpex5-W53A (○), ldpex5-W293A (▲), ldpex5-W176,293A (●), or ldpex5-W53,176,293A (□). Bound LdPEX5 or ldpex5 proteins were quantified by an indirect ELISA using anti-LdPEX5 antisera. Each assay was performed in triplicate and the average absorbance values were plotted as a function of the log of the LdPEX5 or ldpex5 concentration using the ORIGIN 7.0 software. K_d values were determined as the protein concentration that gave half the maximal LdPEX5 or ldpex5 binding.